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  • richardmitnick 4:21 pm on January 24, 2022 Permalink | Reply
    Tags: "The Higgs boson could have kept our universe from collapsing", , , , , , , , , Particle Physics,   

    From Live Science: “The Higgs boson could have kept our universe from collapsing” 

    From Live Science

    1.24.22
    Paul Sutter

    Other patches in the multiverse would have, instead, met their ends.

    1
    Physicists have proposed our universe might be a tiny patch of a much larger cosmos that is constantly and rapidly inflating and popping off new universes. In our corner of this multiverse, the mass of the Higgs boson was low enough that this patch did not collapse like others may have. Image credit: MARK GARLICK/SCIENCE PHOTO LIBRARY via Getty Images.

    The Higgs boson, the mysterious particle that lends other particles their mass, could have kept our universe from collapsing. And its properties might be a clue that we live in a multiverse of parallel worlds, a wild new theory suggests.

    That theory, in which different regions of the universe have different sets of physical laws, would suggest that only worlds in which the Higgs boson is tiny would survive.

    If true, the new model would entail the creation of new particles, which in turn would explain why the strong interaction — which ultimately keeps atoms from collapsing — seems to obey certain symmetries. And along the way, it could help reveal the nature of Dark Matter — the elusive substance that makes up most matter.

    A tale of two Higgs

    In 2012, the Large Hadron Collider achieved a truly monumental feat; this underground particle accelerator along the French-Swiss border detected for the first time the Higgs boson, a particle that had eluded physicists for decades.

    The European Organization for Nuclear Research [Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) [CERN].

    The European Organization for Nuclear Research [Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH)[CERN] map.

    CERN LHC tube in the tunnel. Credit: Maximilien Brice and Julien Marius Ordan.

    SixTRack CERN LHC particles.

    The Higgs boson is a cornerstone of the Standard Model.

    European Organization for Nuclear Research [Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) ATLAS Higgs Event June 18, 2012.

    European Organization for Nuclear Research [Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) CMS Higgs Event May 27, 2012.

    This particle gives other particles their mass and creates the distinction between the weak interaction and the electromagnetic interaction.

    But with the good news came some bad. The Higgs had a mass of 125 gigaelectronvolts (GeV), which was orders of magnitude smaller than what physicists had thought it should be.

    To be perfectly clear, the framework physicists use to describe the zoo of subatomic particles, known as the Standard Model, doesn’t actually predict the value of the Higgs mass.

    Standard Model of Particle Physics, Quantum Diaries.

    For that theory to work, the number has to be derived experimentally. But back-of-the-envelope calculations made physicists guess that the Higgs would have an incredibly large mass. So once the champagne was opened and the Nobel prizes were handed out, the question loomed: Why does the Higgs have such a low mass?

    In another, and initially unrelated problem, the strong interaction isn’t exactly behaving as the Standard Model predicts it should. In the mathematics that physicists use to describe high-energy interactions, there are certain symmetries. For example, there is the symmetry of charge (change all the electric charges in an interaction and everything operates the same), the symmetry of time (run a reaction backward and it’s the same), and the symmetry of parity (flip an interaction around to its mirror-image and it’s the same).

    In all experiments performed to date, the strong interaction appears to obey the combined symmetry of both charge reversal and parity reversal. But the mathematics of the strong interaction do not show that same symmetry. No known natural phenomena should enforce that symmetry, and yet nature seems to be obeying it.

    What gives?

    A matter of multiverses

    A pair of theorists, Raffaele Tito D’Agnolo of the French Alternative Energies and Atomic Energy Commission (CEA) and Daniele Teresi of CERN, thought that these two problems might be related. In a paper published in January to the journal Physical Review Letters, they outlined their solution to the twin conundrums.

    Their solution: The universe was just born that way.

    They invoked an idea called the multiverse, which is born out of a theory called inflation. Inflation is the idea that in the earliest days of the Big Bang, our cosmos underwent a period of extremely enhanced expansion, doubling in size every billionth of a second.

    _____________________________________________________________________________________
    Inflation

    4
    Alan Guth, from M.I.T., who first proposed cosmic inflation.

    Lamda Cold Dark Matter Accerated Expansion of The universe http scinotions.com the-cosmic-inflation-suggests-the-existence-of-parallel-universes. Credit: Alex Mittelmann.

    Alan Guth’s notes:
    Alan Guth’s original notes on inflation.
    _____________________________________________________________________________________

    Physicists aren’t exactly sure what powered inflation or how it worked, but one outgrowth of the basic idea is that our universe has never stopped inflating. Instead, what we call “our universe” is just one tiny patch of a much larger cosmos that is constantly and rapidly inflating and constantly popping off new universes, like foamy suds in your bathtub.

    Different regions of this “multiverse” will have different values of the Higgs mass. The researchers found that universes with a large Higgs mass find themselves catastrophically collapsing before they get a chance to grow. Only the regions of the multiverse that have low Higgs masses survive and have stable expansion rates, leading to the development of galaxies, stars, planets and eventually high-energy particle colliders.

    To make a multiverse with varying Higgs masses, the team had to introduce two more particles into the mix. These particles would be new additions to the Standard Model. The interactions of these two new particles set the mass of the Higgs in different regions of the multiverse.

    And those two new particles are also capable of doing other things.

    Time for a test

    The newly proposed particles modify the strong interaction, leading to the charge-parity symmetry that exists in nature. They would act a lot like an axion, another hypothetical particle that has been introduced in an attempt to explain the nature of the strong interaction.

    The new particles don’t have a role limited to the early universe, either. They might still be inhabiting the present-day cosmos. If one of their masses is small enough, it could have evaded detection in our accelerator experiments, but would still be floating around in space.

    In other words, one of these new particles could be responsible for the Dark Matter, the invisible stuff that makes up over 85% of all the matter in the universe.

    It’s a bold suggestion: solving two of the greatest challenges to particle physics and also explaining the nature of Dark Matter.

    Could a solution really be this simple? As elegant as it is, the theory still needs to be tested. The model predicts a certain mass range for the Dark Matter, something that future experiments that are on the hunt for dark matter, like the underground facility the Super Cryogenic Dark Matter Search, could determine. Also, the theory predicts that the neutron should have a small but potentially measurable asymmetry in the electric charges within the neutron, a difference from the predictions of the Standard Model.

    Unfortunately, we’re going to have to wait awhile. Each of these measurements will take years, if not decades, to effectively rule out — or support – the new idea.

    ______________________________________________________
    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM, denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky.
    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.
    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.
    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

    Vera Rubin measuring spectra, worked on Dark Matter(Emilio Segre Visual Archives AIP SPL).
    Dark Matter Research

    Super Cryogenic Dark Matter Search from DOE’s SLAC National Accelerator Laboratory (US) at Stanford University (US) at SNOLAB (Vale Inco Mine, Sudbury, Canada).

    LBNL LZ Dark Matter Experiment (US) xenon detector at Sanford Underground Research Facility(US) Credit: Matt Kapust.

    Lamda Cold Dark Matter Accerated Expansion of The universe http scinotions.com the-cosmic-inflation-suggests-the-existence-of-parallel-universes. Credit: Alex Mittelmann.

    DAMA at Gran Sasso uses sodium iodide housed in copper to hunt for dark matter LNGS-INFN.

    Yale HAYSTAC axion dark matter experiment at Yale’s Wright Lab.

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB (CA) deep in Sudbury’s Creighton Mine.

    The LBNL LZ Dark Matter Experiment (US) Dark Matter project at SURF, Lead, SD, USA.

    DAMA-LIBRA Dark Matter experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS) located in the Abruzzo region of central Italy.

    DARWIN Dark Matter experiment. A design study for a next-generation, multi-ton dark matter detector in Europe at The University of Zurich [Universität Zürich](CH).

    PandaX II Dark Matter experiment at Jin-ping Underground Laboratory (CJPL) in Sichuan, China.

    Inside the Axion Dark Matter eXperiment U Washington (US) Credit : Mark Stone U. of Washington. Axion Dark Matter Experiment.
    ______________________________________________________

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 9:45 am on January 24, 2022 Permalink | Reply
    Tags: "At the interface of physics and mathematics", , , Integrable model: equation that can be solved exactly., , Particle Physics, , , String Theory-which scientists hope will eventually provide a unified description of particle physics and gravity., ,   

    From The Swiss Federal Institute of Technology in Zürich [ETH Zürich] [Eidgenössische Technische Hochschule Zürich] (CH): “At the interface of physics and mathematics” 

    From The Swiss Federal Institute of Technology in Zürich [ETH Zürich] [Eidgenössische Technische Hochschule Zürich] (CH)

    24.01.2022
    Barbara Vonarburg

    Sylvain Lacroix is a theoretical physicist who conducts research into fundamental concepts of physics – an exciting but intellectually challenging field of science. As an Advanced Fellow at ETH Zürich’s Institute for Theoretical Studies (ITS), he works on complex equations that can be solved exactly only thanks to their large number of symmetries.

    1
    “It was fascinating to learn abstract mathematical concepts and see them neatly applied in the realm of physics,” says Sylvain Lacroix, Advanced Fellow at the Institute for Theoretical Studies. Photo: Nicola Pitaro/ETH Zürich.

    “I got hooked on the interplay of physics and mathematics while I was still at secondary school,” says 30-​year-old Sylvain Lacroix, who was born and grew up near Paris. “It was fascinating to learn abstract mathematical concepts and see them neatly applied in the realm of physics.” During his studies at The University of Lyon [Université Claude Bernard Lyon 1] (FR), he devoted much of his energy and enthusiasm to physics problems that had highly complex underlying mathematical structures. So when it came to selecting a topic for his doctoral thesis, this area of research seemed like the obvious choice. He decided to explore the theory of what are known as integrable models – a subject he has continued to pursue up to the present day.

    Lacroix readily acknowledges that most people outside his line of work find the term “integrable models” completely incomprehensible: “I have to admit that it’s probably not the simplest or most accessible field of physics,” he says, almost apologetically. That’s why he takes pains to explain it in layman’s terms: “We define a model as a body of laws, a set of equations that describe the behaviour of certain quantities, for example how the position of an object changes over time.” An integrable model is characterised by equations that can be solved exactly, which is by no means a given.

    Symmetry is the key

    Many of the equations used in modern physics – such as that practised at The European Organization for Nuclear Research [Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) [CERN] – are so complex that they can be solved only approximately. These approximation methods often serve their purpose well, for instance if there is only a weak interaction between two particles. However, other cases require exact calculations – and that’s where integrable models come in. But what makes them so exact? “That’s another aspect that is tricky to explain,” Lacroix says, “but it ultimately comes down to symmetry.” Take, for example, the symmetry of time or space: a physics experiment will produce the same results whether you perform it today or – under identical conditions – ten days from now, and whether it takes place in Zürich or New York. Consequently, the equation that describes the experiment must remain invariant even if the time or location changes. This is reflected in the mathematical structure of the equation, which contains the corresponding constraints. “If we have enough symmetries, this results in so many constraints that we can simplify the equation to the point where we get exact results,” says the physicist.

    Integrable models and their exact solutions are actually very rare in mathematics. “If I chose a random equation, it would be extremely unlikely to have this property of exact solvability,” Lacroix says. “But equations of this kind really do exist in nature.” Some describe the movement of waves propagating in a channel, for example, while others describe the behaviour of a hydrogen atom. “But it’s important to note that my work doesn’t have any practical applications of that kind,” Lacroix says. “I don’t examine concrete physical models; instead, I study mathematical structures and attempt to find general approaches that will allow us to construct new exactly solvable equations.” Although some of these formulas may eventually find a real-​world application, others probably won’t.

    After completing his doctoral thesis, Lacroix spent three years working as a postdoc at The University of Hamburg [Universität Hamburg](DE), before finally moving to Zürich in September 2021. “I don’t have a family, so I had no problem making the switch,” he says. He is relieved that he can now spend five years at the ITS as an Advanced Fellow and focus entirely on his research without having to worry about the future. He admits it was a pleasure getting to know different countries as a postdoc and that he enjoyed moving from place to place. “But it makes it very hard to have any kind of stability in your life.”

    A beautiful setting

    Lacroix spends most of his time working in his office at the ITS, which is located in a stately building dating from 1882 not far from the ETH Main Building. “It’s a lovely place,” he says, glancing out the window at the green surroundings and the city beyond. “I feel very much at home here. Living in Zürich is wonderful, it’s such a great feeling being here.” In his spare time, he likes watching movies, reading books and socialising. “I love meeting up with friends in restaurants or cafés,” he says. He also feels fortunate that he didn’t start working in Zürich until after the Covid measures had been relaxed.

    “I’m vaccinated and everyone’s very careful at ETH. We still have restrictions in place, but life is slowly getting back to normal – and that made it much easier to get to know my colleagues from day one,” he says. One of the greatest privileges of working at the ITS, Lacroix says, is that it offers an international environment that brings together researchers from all over the world. As well as offering a space for experts to exchange ideas and holding seminars where Fellows can present their work, the Institute also has a tradition of organising joint excursions. In the autumn of 2021, Lacroix joined his colleagues on a hike in the Flumserberg mountain resort for the first time: “I love hiking and it’s incredible to have the mountains so close.”

    Normally, however, he can be found sitting at his desk jotting down a series of mostly abstract equations on a sheet of paper. Occasionally his computer comes in handy, he says, because it has become so much more than just a calculating device; today’s computers can also handle abstract mathematical concepts, which can be very useful. Most people don’t really understand much of what Lacroix puts down on paper, but that doesn’t bother him: “I’ve learned to live with that,” he says; “I don’t feel isolated in my research at all – at least not in the academic sphere.”

    A better understanding of quantum field theory

    Integrable models are extremely symmetrical models, Lacroix explains. The basic principle of symmetry plays an important role in modern physics, for example in quantum field theory – the theoretical basis of particle physics – as well as in string theory, which scientists hope will eventually provide a unified description of particle physics and gravity. So could such an all-​encompassing unified field theory turn out to be an integrable model? “That would obviously be great, especially for me!” Lacroix says with a wry smile. “But it’s a bit optimistic to believe that whatever unified theory of physics finally emerges will have enough symmetries to make it completely exact.”

    Even if the equations he studies don’t explain the world directly, he still believes they can help us achieve a better understanding of theoretical physics. For example, we can take advantage of so-​called “toy models”, which have a particularly large number of symmetries, to simplify extremely complex equations in quantum field theory. “This gives us a better understanding of how the theory works, even if these models are too simplistic for the real world,” Lacroix says. Yet his primary interest lies in the purely mathematical questions that integrable models pose, and he admits that the equations they involve sometimes even appear in his dreams: “It’s hard to shake off what I’ve been thinking about the entire day. But I’ve never managed to solve a mathematical problem in my dreams – at least not so far!”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    ETH Zurich campus

    The Swiss Federal Institute of Technology in Zürich [ETH Zürich] [Eidgenössische Technische Hochschule Zürich] (CH) is a public research university in the city of Zürich, Switzerland. Founded by the Swiss Federal Government in 1854 with the stated mission to educate engineers and scientists, the school focuses exclusively on science, technology, engineering and mathematics. Like its sister institution The Swiss Federal Institute of Technology in Lausanne [EPFL-École Polytechnique Fédérale de Lausanne](CH) , it is part of The Swiss Federal Institutes of Technology Domain (ETH Domain)) , part of the The Swiss Federal Department of Economic Affairs, Education and Research [EAER][Eidgenössisches Departement für Wirtschaft, Bildung und Forschung] [Département fédéral de l’économie, de la formation et de la recherche] (CH).

    The university is an attractive destination for international students thanks to low tuition fees of 809 CHF per semester, PhD and graduate salaries that are amongst the world’s highest, and a world-class reputation in academia and industry. There are currently 22,200 students from over 120 countries, of which 4,180 are pursuing doctoral degrees. In the 2021 edition of the QS World University Rankings ETH Zürich is ranked 6th in the world and 8th by the Times Higher Education World Rankings 2020. In the 2020 QS World University Rankings by subject it is ranked 4th in the world for engineering and technology (2nd in Europe) and 1st for earth & marine science.

    As of November 2019, 21 Nobel laureates, 2 Fields Medalists, 2 Pritzker Prize winners, and 1 Turing Award winner have been affiliated with the Institute, including Albert Einstein. Other notable alumni include John von Neumann and Santiago Calatrava. It is a founding member of the IDEA League and the International Alliance of Research Universities (IARU) and a member of the CESAER network.

    ETH Zürich was founded on 7 February 1854 by the Swiss Confederation and began giving its first lectures on 16 October 1855 as a polytechnic institute (eidgenössische polytechnische Schule) at various sites throughout the city of Zurich. It was initially composed of six faculties: architecture, civil engineering, mechanical engineering, chemistry, forestry, and an integrated department for the fields of mathematics, natural sciences, literature, and social and political sciences.

    It is locally still known as Polytechnikum, or simply as Poly, derived from the original name eidgenössische polytechnische Schule, which translates to “federal polytechnic school”.

    ETH Zürich is a federal institute (i.e., under direct administration by the Swiss government), whereas The University of Zürich [Universität Zürich ] (CH) is a cantonal institution. The decision for a new federal university was heavily disputed at the time; the liberals pressed for a “federal university”, while the conservative forces wanted all universities to remain under cantonal control, worried that the liberals would gain more political power than they already had. In the beginning, both universities were co-located in the buildings of the University of Zürich.

    From 1905 to 1908, under the presidency of Jérôme Franel, the course program of ETH Zürich was restructured to that of a real university and ETH Zürich was granted the right to award doctorates. In 1909 the first doctorates were awarded. In 1911, it was given its current name, Eidgenössische Technische Hochschule. In 1924, another reorganization structured the university in 12 departments. However, it now has 16 departments.

    ETH Zürich, EPFL (Swiss Federal Institute of Technology in Lausanne) [École polytechnique fédérale de Lausanne](CH), and four associated research institutes form The Domain of the Swiss Federal Institutes of Technology (ETH Domain) [ETH-Bereich; Domaine des Écoles polytechniques fédérales] (CH) with the aim of collaborating on scientific projects.

    Reputation and ranking

    ETH Zürich is ranked among the top universities in the world. Typically, popular rankings place the institution as the best university in continental Europe and ETH Zürich is consistently ranked among the top 1-5 universities in Europe, and among the top 3-10 best universities of the world.

    Historically, ETH Zürich has achieved its reputation particularly in the fields of chemistry, mathematics and physics. There are 32 Nobel laureates who are associated with ETH Zürich, the most recent of whom is Richard F. Heck, awarded the Nobel Prize in chemistry in 2010. Albert Einstein is perhaps its most famous alumnus.

    In 2018, the QS World University Rankings placed ETH Zürich at 7th overall in the world. In 2015, ETH Zürich was ranked 5th in the world in Engineering, Science and Technology, just behind the Massachusetts Institute of Technology(US), Stanford University(US) and University of Cambridge(UK). In 2015, ETH Zürich also ranked 6th in the world in Natural Sciences, and in 2016 ranked 1st in the world for Earth & Marine Sciences for the second consecutive year.

    In 2016, Times Higher Education World University Rankings ranked ETH Zürich 9th overall in the world and 8th in the world in the field of Engineering & Technology, just behind the Massachusetts Institute of Technology(US), Stanford University(US), California Institute of Technology(US), Princeton University(US), University of Cambridge(UK), Imperial College London(UK) and University of Oxford(UK) .

    In a comparison of Swiss universities by swissUP Ranking and in rankings published by CHE comparing the universities of German-speaking countries, ETH Zürich traditionally is ranked first in natural sciences, computer science and engineering sciences.

    In the survey CHE ExcellenceRanking on the quality of Western European graduate school programs in the fields of biology, chemistry, physics and mathematics, ETH Zürich was assessed as one of the three institutions to have excellent programs in all the considered fields, the other two being Imperial College London(UK) and The University of Cambridge(UK), respectively.

     
  • richardmitnick 5:36 pm on January 23, 2022 Permalink | Reply
    Tags: "Scientists make first detection of exotic “X” particles in quark-gluon plasma", , , , In the next few years scientists want to use the quark-gluon plasma to probe the X particle’s internal structure which could change our view of what kind of material the universe should produce., MIT’s Laboratory for Nuclear Science, Particle Physics, Scientists suspect that X (3872) is either a compact tetraquark or a new kind of molecule made two loosely bound mesons-subatomic particles that themselves are made from two quarks., , The researchers were able to tease out about 100 X particles of a type known as X (3872) named for the particle’s estimated mass., The study’s co-authors are members of the CMS Collaboration., The team used machine-learning techniques to sift through more than 13 billion heavy ion collisions., These findings could redefine the kinds of particles that were abundant in the early universe., X (3872) was first discovered in 2003 by the Belle experiment-a particle collider in Japan that smashes together high-energy electrons and positrons., [Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) [CERN]   

    From The Massachusetts Institute of Technology (US): “Scientists make first detection of exotic “X” particles in quark-gluon plasma” 

    MIT News

    From The Massachusetts Institute of Technology (US)

    January 21, 2022
    Jennifer Chu

    The findings could redefine the kinds of particles that were abundant in the early universe.

    1
    Physicists have found evidence of rare X particles in the quark-gluon plasma produced in the Large Hadron Collider (LHC) at CERN. The findings could redefine the kinds of particles that were abundant in the early universe. Image: iStockphoto.

    In the first millionths of a second after the Big Bang, the universe was a roiling, trillion-degree plasma of quarks and gluons — elementary particles that briefly glommed together in countless combinations before cooling and settling into more stable configurations to make the neutrons and protons of ordinary matter.

    In the chaos before cooling, a fraction of these quarks and gluons collided randomly to form short-lived “X” particles, so named for their mysterious, unknown structures. Today, X particles are extremely rare, though physicists have theorized that they may be created in particle accelerators through quark coalescence, where high-energy collisions can generate similar flashes of quark-gluon plasma.

    Now physicists at MIT’s Laboratory for Nuclear Science and elsewhere have found evidence of X particles in the quark-gluon plasma produced in the Large Hadron Collider (LHC) at CERN, the European Organization for Nuclear Research, based near Geneva, Switzerland.

    The European Organization for Nuclear Research [Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) [CERN].

    The European Organization for Nuclear Research [Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH)[CERN] map.

    CERN LHC tube in the tunnel. Credit: Maximilien Brice and Julien Marius Ordan.

    SixTRack CERN LHC particles.

    The team used machine-learning techniques to sift through more than 13 billion heavy ion collisions, each of which produced tens of thousands of charged particles. Amid this ultradense, high-energy particle soup, the researchers were able to tease out about 100 X particles of a type known as X (3872) named for the particle’s estimated mass.

    The results, published this week in Physical Review Letters, mark the first time researchers have detected X particles in quark-gluon plasma — an environment that they hope will illuminate the particles’ as-yet unknown structure.

    “This is just the start of the story,” says lead author Yen-Jie Lee, the Class of 1958 Career Development Associate Professor of Physics at MIT. “We’ve shown we can find a signal. In the next few years we want to use the quark-gluon plasma to probe the X particle’s internal structure which could change our view of what kind of material the universe should produce.”

    The study’s co-authors are members of the CMS Collaboration, an international team of scientists that operates and collects data from the Compact Muon Solenoid, one of the LHC’s particle detectors.

    The European Organization for Nuclear Research [Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH)[CERN] CMS.

    The European Organization for Nuclear Research [Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH)[CERN] Compact Muon Solenoid Detector.

    X (3872) was first discovered in 2003 by the Belle experiment-a particle collider in Japan that smashes together high-energy electrons and positrons.

    Particles in the plasma

    The basic building blocks of matter are the neutron and the proton, each of which are made from three tightly bound quarks.

    The quark structure of the proton. 16 March 2006 Arpad Horvath.

    The quark structure of the neutron. 15 January 2018 Jacek Rybak.

    “For years we had thought that for some reason, nature had chosen to produce particles made only from two or three quarks,” Lee says.

    Only recently have physicists begun to see signs of exotic “tetraquarks” — particles made from a rare combination of four quarks.

    Tetraquarks-School of Physics and Astronomy – The University of Edinburgh (SCT).

    Scientists suspect that X (3872) is either a compact tetraquark or an entirely new kind of molecule made from not atoms but two loosely bound mesons — subatomic particles that themselves are made from two quarks.

    X (3872) was first discovered in 2003 by the Belle experiment-a particle collider in Japan that smashes together high-energy electrons and positrons.

    KEK Belle II detector, at The High Energy Accelerator Research Organization [高エネルギー加速器研究機構](JP) in Tsukuba, Ibaraki Prefecture, Japan.

    Within this environment, however, the rare particles decayed too quickly for scientists to examine their structure in detail. It has been hypothesized that X (3872) and other exotic particles might be better illuminated in quark-gluon plasma.

    “Theoretically speaking, there are so many quarks and gluons in the plasma that the production of X particles should be enhanced,” Lee says. “But people thought it would be too difficult to search for them because there are so many other particles produced in this quark soup.”

    “Really a signal”

    In their new study, Lee and his colleagues looked for signs of X particles within the quark-gluon plasma generated by heavy-ion collisions in CERN’s Large Hadron Collider. They based their analysis on the LHC’s 2018 dataset, which included more than 13 billion lead-ion collisions, each of which released quarks and gluons that scattered and merged to form more than a quadrillion short-lived particles before cooling and decaying.

    “After the quark-gluon plasma forms and cools down, there are so many particles produced, the background is overwhelming,” Lee says. “So we had to beat down this background so that we could eventually see the X particles in our data.”

    To do this, the team used a machine-learning algorithm which they trained to pick out decay patterns characteristic of X particles. Immediately after particles form in quark-gluon plasma, they quickly break down into “daughter” particles that scatter away. For X particles, this decay pattern, or angular distribution, is distinct from all other particles.

    The researchers, led by MIT postdoc Jing Wang, identified key variables that describe the shape of the X particle decay pattern. They trained a machine-learning algorithm to recognize these variables, then fed the algorithm actual data from the LHC’s collision experiments. The algorithm was able to sift through the extremely dense and noisy dataset to pick out the key variables that were likely a result of decaying X particles.

    “We managed to lower the background by orders of magnitude to see the signal,” says Wang.

    The researchers zoomed in on the signals and observed a peak at a specific mass, indicating the presence of X (3872) particles, about 100 in all.

    “It’s almost unthinkable that we can tease out these 100 particles from this huge dataset,” says Lee, who along with Wang ran multiple checks to verify their observation.

    “Every night I would ask myself, is this really a signal or not?” Wang recalls. “And in the end, the data said yes!”

    In the next year or two, the researchers plan to gather much more data, which should help to elucidate the X particle’s structure. If the particle is a tightly bound tetraquark, it should decay more slowly than if it were a loosely bound molecule. Now that the team has shown X particles can be detected in quark-gluon plasma, they plan to probe this particle with quark-gluon plasma in more detail, to pin down the X particle’s structure.

    “Currently our data is consistent with both because we don’t have a enough statistics yet. In next few years we’ll take much more data so we can separate these two scenarios,” Lee says. “That will broaden our view of the kinds of particles that were produced abundantly in the early universe.”

    This research was supported, in part, by the Department of Energy (US).

    See the full article here .

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    Please help promote STEM in your local schools.

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    MIT Campus

    The Massachusetts Institute of Technology (US) is a private land-grant research university in Cambridge, Massachusetts. The institute has an urban campus that extends more than a mile (1.6 km) alongside the Charles River. The institute also encompasses a number of major off-campus facilities such as the MIT Lincoln Laboratory (US), the MIT Bates Research and Engineering Center (US), and the Haystack Observatory (US), as well as affiliated laboratories such as the Broad Institute of MIT and Harvard(US) and Whitehead Institute (US).

    Massachusettes Institute of Technology-Haystack Observatory(US) Westford, Massachusetts, USA, Altitude 131 m (430 ft).

    Founded in 1861 in response to the increasing industrialization of the United States, Massachusetts Institute of Technology (US) adopted a European polytechnic university model and stressed laboratory instruction in applied science and engineering. It has since played a key role in the development of many aspects of modern science, engineering, mathematics, and technology, and is widely known for its innovation and academic strength. It is frequently regarded as one of the most prestigious universities in the world.

    As of December 2020, 97 Nobel laureates, 26 Turing Award winners, and 8 Fields Medalists have been affiliated with MIT as alumni, faculty members, or researchers. In addition, 58 National Medal of Science recipients, 29 National Medals of Technology and Innovation recipients, 50 MacArthur Fellows, 80 Marshall Scholars, 3 Mitchell Scholars, 22 Schwarzman Scholars, 41 astronauts, and 16 Chief Scientists of the U.S. Air Force have been affiliated with The Massachusetts Institute of Technology (US) . The university also has a strong entrepreneurial culture and MIT alumni have founded or co-founded many notable companies. Massachusetts Institute of Technology (US) is a member of the Association of American Universities (AAU).

    Foundation and vision

    In 1859, a proposal was submitted to the Massachusetts General Court to use newly filled lands in Back Bay, Boston for a “Conservatory of Art and Science”, but the proposal failed. A charter for the incorporation of the Massachusetts Institute of Technology, proposed by William Barton Rogers, was signed by John Albion Andrew, the governor of Massachusetts, on April 10, 1861.

    Rogers, a professor from the University of Virginia (US), wanted to establish an institution to address rapid scientific and technological advances. He did not wish to found a professional school, but a combination with elements of both professional and liberal education, proposing that:

    “The true and only practicable object of a polytechnic school is, as I conceive, the teaching, not of the minute details and manipulations of the arts, which can be done only in the workshop, but the inculcation of those scientific principles which form the basis and explanation of them, and along with this, a full and methodical review of all their leading processes and operations in connection with physical laws.”

    The Rogers Plan reflected the German research university model, emphasizing an independent faculty engaged in research, as well as instruction oriented around seminars and laboratories.

    Early developments

    Two days after Massachusetts Institute of Technology (US) was chartered, the first battle of the Civil War broke out. After a long delay through the war years, MIT’s first classes were held in the Mercantile Building in Boston in 1865. The new institute was founded as part of the Morrill Land-Grant Colleges Act to fund institutions “to promote the liberal and practical education of the industrial classes” and was a land-grant school. In 1863 under the same act, the Commonwealth of Massachusetts founded the Massachusetts Agricultural College, which developed as the University of Massachusetts Amherst (US)). In 1866, the proceeds from land sales went toward new buildings in the Back Bay.

    Massachusetts Institute of Technology (US) was informally called “Boston Tech”. The institute adopted the European polytechnic university model and emphasized laboratory instruction from an early date. Despite chronic financial problems, the institute saw growth in the last two decades of the 19th century under President Francis Amasa Walker. Programs in electrical, chemical, marine, and sanitary engineering were introduced, new buildings were built, and the size of the student body increased to more than one thousand.

    The curriculum drifted to a vocational emphasis, with less focus on theoretical science. The fledgling school still suffered from chronic financial shortages which diverted the attention of the MIT leadership. During these “Boston Tech” years, Massachusetts Institute of Technology (US) faculty and alumni rebuffed Harvard University (US) president (and former MIT faculty) Charles W. Eliot’s repeated attempts to merge MIT with Harvard College’s Lawrence Scientific School. There would be at least six attempts to absorb MIT into Harvard. In its cramped Back Bay location, MIT could not afford to expand its overcrowded facilities, driving a desperate search for a new campus and funding. Eventually, the MIT Corporation approved a formal agreement to merge with Harvard, over the vehement objections of MIT faculty, students, and alumni. However, a 1917 decision by the Massachusetts Supreme Judicial Court effectively put an end to the merger scheme.

    In 1916, the Massachusetts Institute of Technology (US) administration and the MIT charter crossed the Charles River on the ceremonial barge Bucentaur built for the occasion, to signify MIT’s move to a spacious new campus largely consisting of filled land on a one-mile-long (1.6 km) tract along the Cambridge side of the Charles River. The neoclassical “New Technology” campus was designed by William W. Bosworth and had been funded largely by anonymous donations from a mysterious “Mr. Smith”, starting in 1912. In January 1920, the donor was revealed to be the industrialist George Eastman of Rochester, New York, who had invented methods of film production and processing, and founded Eastman Kodak. Between 1912 and 1920, Eastman donated $20 million ($236.6 million in 2015 dollars) in cash and Kodak stock to MIT.

    Curricular reforms

    In the 1930s, President Karl Taylor Compton and Vice-President (effectively Provost) Vannevar Bush emphasized the importance of pure sciences like physics and chemistry and reduced the vocational practice required in shops and drafting studios. The Compton reforms “renewed confidence in the ability of the Institute to develop leadership in science as well as in engineering”. Unlike Ivy League schools, Massachusetts Institute of Technology (US) catered more to middle-class families, and depended more on tuition than on endowments or grants for its funding. The school was elected to the Association of American Universities (US)in 1934.

    Still, as late as 1949, the Lewis Committee lamented in its report on the state of education at Massachusetts Institute of Technology (US) that “the Institute is widely conceived as basically a vocational school”, a “partly unjustified” perception the committee sought to change. The report comprehensively reviewed the undergraduate curriculum, recommended offering a broader education, and warned against letting engineering and government-sponsored research detract from the sciences and humanities. The School of Humanities, Arts, and Social Sciences and the MIT Sloan School of Management were formed in 1950 to compete with the powerful Schools of Science and Engineering. Previously marginalized faculties in the areas of economics, management, political science, and linguistics emerged into cohesive and assertive departments by attracting respected professors and launching competitive graduate programs. The School of Humanities, Arts, and Social Sciences continued to develop under the successive terms of the more humanistically oriented presidents Howard W. Johnson and Jerome Wiesner between 1966 and 1980.

    Massachusetts Institute of Technology (US)‘s involvement in military science surged during World War II. In 1941, Vannevar Bush was appointed head of the federal Office of Scientific Research and Development and directed funding to only a select group of universities, including MIT. Engineers and scientists from across the country gathered at Massachusetts Institute of Technology (US)’s Radiation Laboratory, established in 1940 to assist the British military in developing microwave radar. The work done there significantly affected both the war and subsequent research in the area. Other defense projects included gyroscope-based and other complex control systems for gunsight, bombsight, and inertial navigation under Charles Stark Draper’s Instrumentation Laboratory; the development of a digital computer for flight simulations under Project Whirlwind; and high-speed and high-altitude photography under Harold Edgerton. By the end of the war, Massachusetts Institute of Technology (US) became the nation’s largest wartime R&D contractor (attracting some criticism of Bush), employing nearly 4000 in the Radiation Laboratory alone and receiving in excess of $100 million ($1.2 billion in 2015 dollars) before 1946. Work on defense projects continued even after then. Post-war government-sponsored research at MIT included SAGE and guidance systems for ballistic missiles and Project Apollo.

    These activities affected Massachusetts Institute of Technology (US) profoundly. A 1949 report noted the lack of “any great slackening in the pace of life at the Institute” to match the return to peacetime, remembering the “academic tranquility of the prewar years”, though acknowledging the significant contributions of military research to the increased emphasis on graduate education and rapid growth of personnel and facilities. The faculty doubled and the graduate student body quintupled during the terms of Karl Taylor Compton, president of Massachusetts Institute of Technology (US) between 1930 and 1948; James Rhyne Killian, president from 1948 to 1957; and Julius Adams Stratton, chancellor from 1952 to 1957, whose institution-building strategies shaped the expanding university. By the 1950s, Massachusetts Institute of Technology (US) no longer simply benefited the industries with which it had worked for three decades, and it had developed closer working relationships with new patrons, philanthropic foundations and the federal government.

    In late 1960s and early 1970s, student and faculty activists protested against the Vietnam War and Massachusetts Institute of Technology (US)’s defense research. In this period Massachusetts Institute of Technology (US)’s various departments were researching helicopters, smart bombs and counterinsurgency techniques for the war in Vietnam as well as guidance systems for nuclear missiles. The Union of Concerned Scientists was founded on March 4, 1969 during a meeting of faculty members and students seeking to shift the emphasis on military research toward environmental and social problems. Massachusetts Institute of Technology (US) ultimately divested itself from the Instrumentation Laboratory and moved all classified research off-campus to the MIT (US) Lincoln Laboratory facility in 1973 in response to the protests. The student body, faculty, and administration remained comparatively unpolarized during what was a tumultuous time for many other universities. Johnson was seen to be highly successful in leading his institution to “greater strength and unity” after these times of turmoil. However six Massachusetts Institute of Technology (US) students were sentenced to prison terms at this time and some former student leaders, such as Michael Albert and George Katsiaficas, are still indignant about MIT’s role in military research and its suppression of these protests. (Richard Leacock’s film, November Actions, records some of these tumultuous events.)

    In the 1980s, there was more controversy at Massachusetts Institute of Technology (US) over its involvement in SDI (space weaponry) and CBW (chemical and biological warfare) research. More recently, Massachusetts Institute of Technology (US)’s research for the military has included work on robots, drones and ‘battle suits’.

    Recent history

    Massachusetts Institute of Technology (US) has kept pace with and helped to advance the digital age. In addition to developing the predecessors to modern computing and networking technologies, students, staff, and faculty members at Project MAC, the Artificial Intelligence Laboratory, and the Tech Model Railroad Club wrote some of the earliest interactive computer video games like Spacewar! and created much of modern hacker slang and culture. Several major computer-related organizations have originated at MIT since the 1980s: Richard Stallman’s GNU Project and the subsequent Free Software Foundation were founded in the mid-1980s at the AI Lab; the MIT Media Lab was founded in 1985 by Nicholas Negroponte and Jerome Wiesner to promote research into novel uses of computer technology; the World Wide Web Consortium standards organization was founded at the Laboratory for Computer Science in 1994 by Tim Berners-Lee; the MIT OpenCourseWare project has made course materials for over 2,000 Massachusetts Institute of Technology (US) classes available online free of charge since 2002; and the One Laptop per Child initiative to expand computer education and connectivity to children worldwide was launched in 2005.

    Massachusetts Institute of Technology (US) was named a sea-grant college in 1976 to support its programs in oceanography and marine sciences and was named a space-grant college in 1989 to support its aeronautics and astronautics programs. Despite diminishing government financial support over the past quarter century, MIT launched several successful development campaigns to significantly expand the campus: new dormitories and athletics buildings on west campus; the Tang Center for Management Education; several buildings in the northeast corner of campus supporting research into biology, brain and cognitive sciences, genomics, biotechnology, and cancer research; and a number of new “backlot” buildings on Vassar Street including the Stata Center. Construction on campus in the 2000s included expansions of the Media Lab, the Sloan School’s eastern campus, and graduate residences in the northwest. In 2006, President Hockfield launched the MIT Energy Research Council to investigate the interdisciplinary challenges posed by increasing global energy consumption.

    In 2001, inspired by the open source and open access movements, Massachusetts Institute of Technology (US) launched OpenCourseWare to make the lecture notes, problem sets, syllabi, exams, and lectures from the great majority of its courses available online for no charge, though without any formal accreditation for coursework completed. While the cost of supporting and hosting the project is high, OCW expanded in 2005 to include other universities as a part of the OpenCourseWare Consortium, which currently includes more than 250 academic institutions with content available in at least six languages. In 2011, Massachusetts Institute of Technology (US) announced it would offer formal certification (but not credits or degrees) to online participants completing coursework in its “MITx” program, for a modest fee. The “edX” online platform supporting MITx was initially developed in partnership with Harvard and its analogous “Harvardx” initiative. The courseware platform is open source, and other universities have already joined and added their own course content. In March 2009 the Massachusetts Institute of Technology (US) faculty adopted an open-access policy to make its scholarship publicly accessible online.

    Massachusetts Institute of Technology (US) has its own police force. Three days after the Boston Marathon bombing of April 2013, MIT Police patrol officer Sean Collier was fatally shot by the suspects Dzhokhar and Tamerlan Tsarnaev, setting off a violent manhunt that shut down the campus and much of the Boston metropolitan area for a day. One week later, Collier’s memorial service was attended by more than 10,000 people, in a ceremony hosted by the Massachusetts Institute of Technology (US) community with thousands of police officers from the New England region and Canada. On November 25, 2013, Massachusetts Institute of Technology (US) announced the creation of the Collier Medal, to be awarded annually to “an individual or group that embodies the character and qualities that Officer Collier exhibited as a member of the Massachusetts Institute of Technology (US) community and in all aspects of his life”. The announcement further stated that “Future recipients of the award will include those whose contributions exceed the boundaries of their profession, those who have contributed to building bridges across the community, and those who consistently and selflessly perform acts of kindness”.

    In September 2017, the school announced the creation of an artificial intelligence research lab called the MIT-IBM Watson AI Lab. IBM will spend $240 million over the next decade, and the lab will be staffed by MIT and IBM scientists. In October 2018 MIT announced that it would open a new Schwarzman College of Computing dedicated to the study of artificial intelligence, named after lead donor and The Blackstone Group CEO Stephen Schwarzman. The focus of the new college is to study not just AI, but interdisciplinary AI education, and how AI can be used in fields as diverse as history and biology. The cost of buildings and new faculty for the new college is expected to be $1 billion upon completion.

    The Caltech/MIT Advanced aLIGO (US) was designed and constructed by a team of scientists from California Institute of Technology (US), Massachusetts Institute of Technology (US), and industrial contractors, and funded by the National Science Foundation (US) .

    Caltech /MIT Advanced aLigo

    It was designed to open the field of gravitational-wave astronomy through the detection of gravitational waves predicted by general relativity. Gravitational waves were detected for the first time by the LIGO detector in 2015. For contributions to the LIGO detector and the observation of gravitational waves, two Caltech physicists, Kip Thorne and Barry Barish, and Massachusetts Institute of Technology (US) physicist Rainer Weiss won the Nobel Prize in physics in 2017. Weiss, who is also an Massachusetts Institute of Technology (US) graduate, designed the laser interferometric technique, which served as the essential blueprint for the LIGO.

    The mission of Massachusetts Institute of Technology (US) is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of The Massachusetts Institute of Technology community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

     
  • richardmitnick 2:35 pm on January 21, 2022 Permalink | Reply
    Tags: "In a Numerical Coincidence Some See Evidence for String Theory", "Massive Gravity", "String universality": a monopoly of string theories among viable fundamental theories of nature, , Asymptotically safe quantum gravity, , Graviton: A graviton is a closed string-or loop-in its lowest-energy vibration mode in which an equal number of waves travel clockwise and counterclockwise around the loop., Lorentz invariance: the same laws of physics must hold from all vantage points., Particle Physics, , , , , ,   

    From Quanta Magazine (US): “In a Numerical Coincidence Some See Evidence for String Theory” 

    From Quanta Magazine (US)

    January 21, 2022
    Natalie Wolchover

    1
    Dorine Leenders for Quanta Magazine.

    In a quest to map out a quantum theory of gravity, researchers have used logical rules to calculate how much Einstein’s theory must change. The result matches string theory perfectly.

    Quantum gravity researchers use “α” to denote the size of the biggest quantum correction to Albert Einstein’s Theory of General Relativity.

    Recently, three physicists calculated a number pertaining to the quantum nature of gravity. When they saw the value, “we couldn’t believe it,” said Pedro Vieira, one of the three.

    Gravity’s quantum-scale details are not something physicists usually know how to quantify, but the trio attacked the problem using an approach that has lately been racking up stunners in other areas of physics. It’s called the bootstrap.

    To bootstrap is to deduce new facts about the world by figuring out what’s compatible with known facts — science’s version of picking yourself up by your own bootstraps. With this method, the trio found a surprising coincidence: Their bootstrapped number closely matched the prediction for the number made by string theory. The leading candidate for the fundamental theory of gravity and everything else, string theory holds that all elementary particles are, close-up, vibrating loops and strings.

    Vieira, Andrea Guerrieri of The Tel Aviv University (IL), and João Penedones of The EPFL (Swiss Federal Institute of Technology in Lausanne) [École polytechnique fédérale de Lausanne](CH) reported their number and the match with string theory’s prediction in Physical Review Letters in August 2021. Quantum gravity theorists have been reading the tea leaves ever since.

    Some interpret the result as a new kind of evidence for string theory, a framework that sorely lacks even the prospect of experimental confirmation, due to the pointlike minuteness of the postulated strings.

    “The hope is that you could prove the inevitability of string theory using these ‘bootstrap’ methods,” said David Simmons-Duffin, a theoretical physicist at The California Institute of Technology (US). “And I think this is a great first step towards that.”

    2
    From left: Pedro Vieira, Andrea Guerrieri and João Penedones.
    Credit: Gabriela Secara / The Perimeter Institute for Theoretical Physics (CA); Courtesy of Andrea Guerrieri; The Swiss National Centres of Competence in Research (NCCRs) [Pôle national suisse de recherche en recherche][Schweizerisches Nationales Kompetenzzentrum für Forschung](CH) SwissMAP (CH)

    Irene Valenzuela, a theoretical physicist at the Institute for Theoretical Physics at The Autonomous University of Madrid [Universidad Autónoma de Madrid](ES), agreed. “One of the questions is if string theory is the unique theory of quantum gravity or not,” she said. “This goes along the lines that string theory is unique.”

    Other commentators saw that as too bold a leap, pointing to caveats about the way the calculation was done.

    Einstein, Corrected

    The number that Vieira, Guerrieri and Penedones calculated is the minimum possible value of “α” (alpha). Roughly, “α” is the size of the first and largest mathematical term that you have to add to Albert Einstein’s gravity equations in order to describe, say, an interaction between two gravitons — the presumed quantum units of gravity.

    Albert Einstein’s 1915 Theory of General Relativity paints gravity as curves in the space-time continuum created by matter and energy. It perfectly describes large-scale behavior such as a planet orbiting a star. But when matter is packed into too-small spaces, General Relativity short-circuits. “Some correction to Einsteinian gravity has to be there,” said Simon Caron-Huot, a theoretical physicist at McGill University (CA).

    Physicists can tidily organize their lack of knowledge of gravity’s microscopic nature using a scheme devised in the 1960s by Kenneth Wilson and Steven Weinberg: They simply add a series of possible “corrections” to General Relativity that might become important at short distances. Say you want to predict the chance that two gravitons will interact in a certain way. You start with the standard mathematical term from Relativity, then add new terms (using any and all relevant variables as building blocks) that matter more as distances get smaller. These mocked-up terms are fronted by unknown numbers labeled “α”, “β”, “γ” and so on, which set their sizes. “Different theories of quantum gravity will lead to different such corrections,” said Vieira, who has joint appointments at The Perimeter Institute for Theoretical Physics (CA), and The International Centre for Theoretical Physics at The South American Institute for Fundamental Research [Instituto sul-Americano de Pesquisa Fundamental] (BR). “So these corrections are our first way to tell such possibilities apart.”

    In practice, “α” has only been explicitly calculated in string theory, and even then only for highly symmetric 10-dimensional universes. The English string theorist Michael Green and colleagues determined in the 1990s that in such worlds “α” must be at least 0.1389. In a given stringy universe it might be higher; how much higher depends on the string coupling constant, or a string’s propensity to spontaneously split into two. (This coupling constant varies between versions of string theory, but all versions unite in a master framework called “M-theory”, where string coupling constants correspond to different positions in an extra 11th dimension.)

    Meanwhile, alternative quantum gravity ideas remain unable to make predictions about “α”. And since physicists can’t actually detect gravitons — the force of gravity is too weak — they haven’t been able to directly measure “α” as a way of investigating and testing quantum gravity theories.

    Then a few years ago, Penedones, Vieira and Guerrieri started talking about using the bootstrap method to constrain what can happen during particle interactions. They first successfully applied the approach to particles called pions. “We said, OK, here it’s working very well, so why not go for gravity?” Guerrieri said.

    Bootstrapping the Bound

    The trick of using accepted truths to constrain unknown possibilities was devised by particle physicists in the 1960s, then forgotten, then revived to fantastic effect over the past decade by researchers with supercomputers, which can solve the formidable formulas that bootstrapping tends to produce.

    Guerrieri, Vieira and Penedones set out to determine what “α” has to be in order to satisfy two consistency conditions. The first, known as unitarity, states that the probabilities of different outcomes must always add up to 100%. The second, known as Lorentz invariance, says that the same laws of physics must hold from all vantage points.

    The trio specifically considered the range of values of “α” permitted by those two principles in supersymmetric 10D universes. Not only is the calculation simple enough to pull off in that setting (not so, currently, for “α” in 4D universes like our own), but it also allowed them to compare their bootstrapped range to string theory’s prediction that “α” in that 10D setting is 0.1389 or higher.

    Unitarity and Lorentz invariance impose constraints on what can happen in a two-graviton interaction in the following way: When the gravitons approach and scatter off each other, they might fly apart as two gravitons, or morph into three gravitons or any number of other particles. As you crank up the energies of the approaching gravitons, the chance they’ll emerge from the encounter as two gravitons changes — but unitarity demands that this probability never surpass 100%. Lorentz invariance means the probability can’t depend on how an observer is moving relative to the gravitons, restricting the form of the equations. Together the rules yield a complicated bootstrapped expression that “α” must satisfy. Guerrieri, Penedones and Vieira programmed the Perimeter Institute’s computer clusters to solve for values that make the two-graviton interactions unitary and Lorentz-invariant.

    The computer spit out its lower bound for “α”: 0.14, give or take a hundredth — an extremely close and potentially exact match with string theory’s lower bound of 0.1389. In other words, string theory seems to span the whole space of allowed “α” values — at least in the 10D place where the researchers checked. “That was a huge surprise,” Vieira said.

    10-Dimensional Coincidence

    What might the numerical coincidence mean? According to Simmons-Duffin, whose work a few years ago helped drive the bootstrap’s resurgence, “they’re trying to tackle a question [that’s] fundamental and important. Which is: To what extent does string theory as we know it cover the space of all possible theories of quantum gravity?”

    String theory emerged in the 1960s as a putative picture of the stringy glue that binds composite particles called mesons. A different description ended up prevailing for that purpose, but years later people realized that string theory could set its sights higher: If strings are small — so small they look like points — they could serve as nature’s elementary building blocks. Electrons, photons and so on would all be the same kind of fundamental string strummed in different ways. The theory’s selling point is that it gives a quantum description of gravity: A graviton is a closed string, or loop, in its lowest-energy vibration mode, in which an equal number of waves travel clockwise and counterclockwise around the loop. This feature would underlie macroscopic properties of gravity like the corkscrew-patterned polarization of gravitational waves.

    But matching the theory to all other aspects of reality takes some fiddling. To get rid of negative energies that would correspond to unphysical, faster-than-light particles, string theory needs a property called “Supersymmetry”, which doubles the number of its string vibration modes. Every vibration mode corresponding to a matter particle must come with another mode signifying a force particle. String theory also requires the existence of 10 space-time dimensions for the strings to wiggle around in. Yet we haven’t found any supersymmetric partner particles, and our universe looks 4D, with three dimensions of space and one of time.

    Standard Model of Supersymmetry

    Both of these data points present something of a problem.

    If string theory describes our world, Supersymmetry must be broken here. That means the partner particles, if they exist, must be far heavier than the known set of particles — too heavy to muster in experiments. And if there really are 10 dimensions, six must be curled up so small they’re imperceptible to us — tight little knots of extra directions you can go in at any point in space. These “compactified” dimensions in a 4D-looking universe could have countless possible arrangements, all affecting strings (and numbers like “α”) differently.

    Broken Supersymmetry and invisible dimensions have led many quantum gravity researchers to seek or prefer alternative, non-stringy ideas.

    Mordehai Milgrom, MOND theorist, is an Israeli physicist and professor in the department of Condensed Matter Physics at The Weizmann Institute of Science (IL) in Rehovot, Israel http://cosmos.nautil.us

    MOND Rotation Curves with MOND Tully-Fisher

    MOND 1

    But so far the rival approaches have struggled to produce the kind of concrete calculations about things like graviton interactions that string theory can.

    Some physicists hope to see string theory win hearts and minds by default, by being the only microscopic description of gravity that’s logically consistent. If researchers can prove “string universality,” as this is sometimes called — a monopoly of string theories among viable fundamental theories of nature — we’ll have no choice but to believe in hidden dimensions and an inaudible orchestra of strings.

    To string theory sympathizers, the new bootstrap calculation opens a route to eventually proving string universality, and it gets the journey off to a rip-roaring start.

    Other researchers disagree with those implications. Astrid Eichhorn, a theoretical physicist at The South Danish University [Syddansk Universitet](DK) and The Ruprecht Karl University of Heidelberg [Ruprecht-Karls-Universität Heidelberg](DE) who specializes in a non-stringy approach called asymptotically safe quantum gravity, told me, “I would consider the relevant setting to collect evidence for or against a given quantum theory of gravity to be four-dimensional and non-supersymmetric” universes, since this “best describes our world, at least so far.”

    Eichhorn pointed out that there might be unitary, Lorentz-invariant descriptions of gravitons in 4D that don’t make any sense in 10D. “Simply by this choice of setting one might have ruled out alternative quantum gravity approaches” that are viable, she said.

    Vieira acknowledged that string universality might hold only in 10 dimensions, saying, “It could be that in 10D with supersymmetry, there’s only string theory, and when you go to 4D, there are many theories.” But, he said, “I doubt it.”

    Another critique, though, is that even if string theory saturates the range of allowed “α” values in the 10-dimensional setting the researchers probed, that doesn’t stop other theories from lying in the permitted range. “I don’t see any practical way we’re going to conclude that string theory is the only answer,” said Andrew Tolley of Imperial College London (UK).

    Just the Beginning

    Assessing the meaning of the coincidence will become easier if bootstrappers can generalize and extend similar results to more settings. “At the moment, many, many people are pursuing these ideas in various variations,” said Alexander Zhiboedov, a theoretical physicist at The European Organization for Nuclear Research [Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) [CERN], Europe’s particle physics laboratory.

    Guerrieri, Penedones and Vieira have already completed a “dual” bootstrap calculation, which bounds “α” from below by ruling out solutions less than the minimum rather than solving for viable “α” values above the bound, as they did previously. This dual calculation shows that their computer clusters didn’t simply miss smaller allowed “α” values, which would correspond to additional viable quantum gravity theories outside string theory’s range.

    They also plan to bootstrap the lower bound for worlds with nine large dimensions, where string theory calculations are still under some control (since only one dimension is curled up), to look for more evidence of a correlation. Aside from “α”, bootstrappers also aim to calculate “β” and “γ” — the allowed sizes of the second- and third-biggest quantum gravity corrections— and they have ideas for how to approach harder calculations about worlds where supersymmetry is broken or nonexistent, as it appears to be in reality. In this way they’ll try to carve out the space of allowed quantum gravity theories, and test string universality in the process.

    Claudia de Rham, a theorist at Imperial College, emphasized the need to be “agnostic,” noting that bootstrap principles are useful for exploring more ideas than just string theory. She and Tolley have used positivity — the rule that probabilities are always positive — to constrain a theory called “Massive Gravity”, which may or may not be a realization of string theory. They discovered potentially testable consequences, showing that massive gravity only satisfies positivity if certain exotic particles exist. De Rham sees bootstrap principles and positivity bounds as “one of the most exciting research developments at the moment” in fundamental physics.

    “No one has done this job of taking everything we know and taking consistency and putting it together,” said Zhiboedov. It’s “exciting,” he added, that theorists have work to do “at a very basic level.”

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Formerly known as Simons Science News, Quanta Magazine (US) is an editorially independent online publication launched by the Simons Foundation to enhance public understanding of science. Why Quanta? Albert Einstein called photons “quanta of light.” Our goal is to “illuminate science.” At Quanta Magazine, scientific accuracy is every bit as important as telling a good story. All of our articles are meticulously researched, reported, edited, copy-edited and fact-checked.

     
  • richardmitnick 11:06 pm on January 20, 2022 Permalink | Reply
    Tags: "Worldwide coordinated search for dark matter", A peculiarity of such bosonic fields is that-according to a possible theoretical scenario-they can form patterns and structures., ALPs can also be considered as a classical field oscillating with a certain frequency., ALPs: axion-like particles, , , , Extremely light bosonic particles are considered one of the most promising candidates for "Dark Matter" today., , Helmholtz Institute - Mainz [Helmholtz-Institut Mainz](DE), Particle Physics, , PRISMA+ Cluster of Excellence, , The measurement principle is based on an interaction of dark matter with the nuclear spins of the atoms in the magnetometer., The network meanwhile consists of 14 magnetometers distributed over eight countries worldwide and nine of them provided data for the current analysis.   

    From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE): “Worldwide coordinated search for dark matter” 

    From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE)

    20 January 2022

    Professor Dr. Dmitry Budker
    Quantum, Atomic, and Neutron Physics (QUANTUM)
    Institute of Physics
    Johannes Gutenberg University Mainz
    and
    PRISMA+ Cluster of Excellence
    and
    Helmholtz Institute – Mainz [Helmholtz-Institut Mainz](DE)
    55099 Mainz
    Tel.: +49 6131 39-27414
    budker@uni-mainz.de

    An international team of researchers with key participation from the PRISMA+ Cluster of Excellence at Johannes Gutenberg University Mainz (JGU) and The Helmholtz Institute – Mainz [Helmholtz-Institut Mainz](DE) has published for the first time comprehensive data on the search for dark matter using a worldwide network of optical magnetometers.

    1
    Sketch of the worldwide GNOME network. ©: Hector Masia Roig.

    2
    Mainz-based setup of the GNOME Network. Photo: Hector Masia Roig.

    According to the scientists, Dark Matter fields should produce a characteristic signal pattern that can be detected by correlated measurements at multiple stations of the GNOME network. Analysis of data from a one-month continuous GNOME operation has not yet yielded a corresponding indication. However, the measurement allows to formulate constraints on the characteristics of Dark Matter, as the researchers report in the prestigious journal Nature Physics.

    GNOME stands for Global Network of Optical Magnetometers for Exotic Physics Searches. Behind it are magnetometers distributed around the world in Germany, Serbia, Poland, Israel, South Korea, China, Australia, and the United States. With GNOME, the researchers particularly want to advance the search for Dark Matter – one of the most exciting challenges of fundamental physics in the 21st century. After all, it has long been known that many puzzling astronomical observations, such as the rotation speed of stars in galaxies or the spectrum of the cosmic background radiation, can best be explained by Dark Matter.

    “Extremely light bosonic particles are considered one of the most promising candidates for Dark Matter today. These include so-called axion-like particles – ALPs for short,” said Professor Dr. Dmitry Budker, professor at PRISMA+ and at HIM, an institutional collaboration of Johannes Gutenberg University Mainz and The GSI Helmholtz Centre for Heavy Ion Research [GSI Helmholtzzentrum für Schwerionenforschung-Darmstadt](DE). “They can also be considered as a classical field oscillating with a certain frequency. A peculiarity of such bosonic fields is that – according to a possible theoretical scenario – they can form patterns and structures. As a result, the density of Dark Matter could be concentrated in many different regions – discrete domain walls smaller than a galaxy but much larger than Earth could form, for example.”

    “If such a wall encounters the Earth, it is gradually detected by the GNOME network and can cause transient characteristic signal patterns in the magnetometers,” explained Dr. Arne Wickenbrock, one of the study’s co-authors. “Even more, the signals are correlated with each other in certain ways – depending on how fast the wall is moving and when it reaches each location.”

    The network meanwhile consists of 14 magnetometers distributed over eight countries worldwide-nine of them provided data for the current analysis. The measurement principle is based on an interaction of dark matter with the nuclear spins of the atoms in the magnetometer. The atoms are excited with a laser at a specific frequency, orienting the nuclear spins in one direction. A potential dark matter field can disturb this direction, which is measurable.

    Figuratively speaking, one can imagine that the atoms in the magnetometer initially dance around in confusion, as clarified by Hector Masia-Roig, a doctoral student in the Budker group and also an author of the current study. “When they “hear” the right frequency of laser light, they all spin together. Dark Matter particles can throw the dancing atoms out of balance. We can measure this perturbation very precisely.” Now the network of magnetometers becomes important: When the Earth moves through a spatially limited wall of Dark Matter, the dancing atoms in all stations are gradually disturbed. One of these stations is located in a laboratory at the Helmholtz Institute in Mainz. “Only when we match the signals from all the stations can we assess what triggered the disturbance,”said Masia-Roig. “Applied to the image of the dancing atoms, this means: If we compare the measurement results from all the stations, we can decide whether it was just one brave dancer dancing out of line or actually a global dark matter disturbance.”

    In the current study, the research team analyzes data from a one-month continuous operation of GNOME. The result: Statistically significant signals did not appear in the investigated mass range from one femtoelectronvolt (feV) to 100,000 feV. Conversely, this means that the researchers can narrow down the range in which such signals could theoretically be found even further than before. For scenarios that rely on discrete Dark Matter walls, this is an important result – “even though we have not yet been able to detect such a domain wall with our global ring search,” added Joseph Smiga, another PhD student in Mainz and author of the study.

    Future work of the GNOME collaboration will focus on improving both the magnetometers themselves and the data analysis. In particular, continuous operation should be even more stable. This is important to reliably search for signals that last longer than an hour. In addition, the previous alkali atoms in the magnetometers are to be replaced by noble gases. Under the title “Advanced GNOME”, the researchers expect this to result in considerably better sensitivity for future measurements in the search for ALPs and Dark Matter.

    ______________________________________________________
    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM, denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky.
    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.
    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.
    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

    Vera Rubin measuring spectra, worked on Dark Matter(Emilio Segre Visual Archives AIP SPL).
    Dark Matter Research

    LBNL LZ Dark Matter Experiment (US) xenon detector at Sanford Underground Research Facility(US) Credit: Matt Kapust.

    Lamda Cold Dark Matter Accerated Expansion of The universe http scinotions.com the-cosmic-inflation-suggests-the-existence-of-parallel-universes. Credit: Alex Mittelmann.

    DAMA at Gran Sasso uses sodium iodide housed in copper to hunt for dark matter LNGS-INFN.

    Yale HAYSTAC axion dark matter experiment at Yale’s Wright Lab.

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB (CA) deep in Sudbury’s Creighton Mine.

    The LBNL LZ Dark Matter Experiment (US) Dark Matter project at SURF, Lead, SD, USA.

    DAMA-LIBRA Dark Matter experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS) located in the Abruzzo region of central Italy.

    DARWIN Dark Matter experiment. A design study for a next-generation, multi-ton dark matter detector in Europe at The University of Zurich [Universität Zürich](CH).

    PandaX II Dark Matter experiment at Jin-ping Underground Laboratory (CJPL) in Sichuan, China.

    Inside the Axion Dark Matter eXperiment U Washington (US) Credit : Mark Stone U. of Washington. Axion Dark Matter Experiment.
    ______________________________________________________

    See the full article here.

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE) is a public research university in Mainz, Rhineland Palatinate, Germany, named after the printer Johannes Gutenberg since 1946. With approximately 32,000 students (2018) in about 100 schools and clinics, it is among the largest universities in Germany. Starting on 1 January 2005 the university was reorganized into 11 faculties of study.

    The university is a member of the German U15, a coalition of fifteen major research-intensive and leading medical universities in Germany. The Johannes Gutenberg University is considered one of the most prestigious universities in Germany.

    The university is part of the IT-Cluster Rhine-Main-Neckar. The Johannes Gutenberg University Mainz, The Goethe University Frankfurt(DE) and The Technische Universität Darmstadt(DE) together form the Rhine-Main-Universities (RMU).

    The first University of Mainz goes back to the Archbishop of Mainz, Prince-elector and Reichserzkanzler Adolf II von Nassau. At the time, establishing a university required papal approval and Adolf II initiated the approval process during his time in office. The university, however, was first opened in 1477 by Adolf’s successor to the bishopric, Diether von Isenburg. In 1784 the University was opened up for Protestants and Jews (curator Anselm Franz von Betzel). It fastly became one of the largest Catholic universities in Europe with ten chairs in theology alone. In the confusion after the establishment of the Mainz Republic of 1792 and its subsequent recapture by the Prussians, academic activity came to a gradual standstill. In 1798 the university became active again under French governance, and lectures in the department of medicine took place until 1823. Only the faculty of theology continued teaching during the 19th century, albeit as a theological Seminary (since 1877 “College of Philosophy and Theology”).

    The current Johannes Gutenberg University Mainz was founded in 1946 by the French occupying power. In a decree on 1 March the French military government implied that the University of Mainz would continue to exist: the University shall be “enabled to resume its function”. The remains of anti-aircraft warfare barracks erected in 1938 after the remilitarization of the Rhineland during the Third Reich served as the university’s first buildings and are still in use today.

    The continuation of academic activity between the old university and Johannes Gutenberg University Mainz, in spite of an interruption spanning over 100 years, is contested. During the time up to its reopening only a seminary and midwifery college survived.

    In 1972, the effect of the 1968 student protests began to take a toll on the University’s structure. The departments (Fakultäten) were dismantled and the University was organized into broad fields of study (Fachbereiche). Finally in 1974 Peter Schneider was elected as the first president of what was now a “constituted group-university” institute of higher education. In 1990 Jürgen Zöllner became University President yet spent only a year in the position after he was appointed Minister for “Science and Advanced Education” for the State of Rhineland-Palatinate. As the coordinator for the SPD’s higher education policy, this furloughed professor from the Institute for Physiological Chemistry played a decisive role in the SPD’s higher education policy and in the development of Study Accounts.

     
  • richardmitnick 4:07 pm on January 20, 2022 Permalink | Reply
    Tags: "Going beyond the exascale", , , Classical computers have been central to physics research for decades., , , , Fermilab has used classical computing to simulate lattice quantum chromodynamics., , Particle Physics, , Planning for a future that is still decades out., Quantum computers could enable physicists to tackle questions even the most powerful computers cannot handle., , Quantum computing is here—sort of., , Solving equations on a quantum computer requires completely new ways of thinking about programming and algorithms., , , The biggest place where quantum simulators will have an impact is in discovery science.   

    From Symmetry: “Going beyond the exascale” 

    Symmetry Mag

    From Symmetry

    01/20/22
    Emily Ayshford

    1
    Illustration by Sandbox Studio, Chicago with Ana Kova.

    Quantum computers could enable physicists to tackle questions even the most powerful computers cannot handle.

    After years of speculation, quantum computing is here—sort of.

    Physicists are beginning to consider how quantum computing could provide answers to the deepest questions in the field. But most aren’t getting caught up in the hype. Instead, they are taking what for them is a familiar tack—planning for a future that is still decades out, while making room for pivots, turns and potential breakthroughs along the way.

    “When we’re working on building a new particle collider, that sort of project can take 40 years,” says Hank Lamm, an associate scientist at The DOE’s Fermi National Accelerator Laboratory (US). “This is on the same timeline. I hope to start seeing quantum computing provide big answers for particle physics before I die. But that doesn’t mean there isn’t interesting physics to do along the way.”

    Equations that overpower even supercomputers.

    Classical computers have been central to physics research for decades, and simulations that run on classical computers have guided many breakthroughs. Fermilab, for example, has used classical computing to simulate lattice quantum chromodynamics. Lattice QCD is a set of equations that describe the interactions of quarks and gluons via the strong force.

    Theorists developed lattice QCD in the 1970s. But applying its equations proved extremely difficult. “Even back in the 1980s, many people said that even if they had an exascale computer [a computer that can perform a billion billion calculations per second], they still couldn’t calculate lattice QCD,” Lamm says.

    Depiction of ANL ALCF Cray Intel SC18 Shasta Aurora exascale supercomputer, to be built at DOE’s Argonne National Laboratory (US).

    Depiction of ORNL Cray Frontier Shasta based Exascale supercomputer with Slingshot interconnect featuring high-performance AMD EPYC CPU and AMD Radeon Instinct GPU technology , being built at DOE’s Oak Ridge National Laboratory (US).

    But that turned out not to be true.

    Within the past 10 to 15 years, researchers have discovered the algorithms needed to make their calculations more manageable, while learning to understand theoretical errors and how to ameliorate them. These advances have allowed them to use a lattice simulation, a simulation that uses a volume of a specified grid of points in space and time as a substitute for the continuous vastness of reality.

    Lattice simulations have allowed physicists to calculate the mass of the proton—a particle made up of quarks and gluons all interacting via the strong force—and find that the theoretical prediction lines up well with the experimental result. The simulations have also allowed them to accurately predict the temperature at which quarks should detach from one another in a quark-gluon plasma.

    Quark-Gluon Plasma from BNL Relative Heavy Ion Collider (US).

    DOE’s Brookhaven National Laboratory(US) RHIC Campus

    The limit of these calculations? Along with being approximate, or based on a confined, hypothetical area of space, only certain properties can be computed efficiently. Try to look at more than that, and even the biggest high-performance computer cannot handle all of the possibilities.

    Enter quantum computers.

    Quantum computers are all about possibilities. Classical computers don’t have the memory to compute the many possible outcomes of lattice QCD problems, but quantum computers take advantage of quantum mechanics to calculate differently.

    Quantum computing isn’t an easy answer, though. Solving equations on a quantum computer requires completely new ways of thinking about programming and algorithms.

    Using a classical computer, when you program code, you can look at its state at all times. You can check a classical computer’s work before it’s done and trouble-shoot if things go wrong. But under the laws of quantum mechanics, you cannot observe any intermediate step of a quantum computation without corrupting the computation; you can observe only the final state.

    That means you can’t store any information in an intermediate state and bring it back later, and you cannot clone information from one set of qubits into another, making error correction difficult.

    “It can be a nightmare designing an algorithm for quantum computation,” says Lamm, who spends his days trying to figure out how to do quantum simulations for high-energy physics. “Everything has to be redesigned from the ground up. We are right at the beginning of understanding how to do this.”

    Just getting started

    Quantum computers have already proved useful in basic research. Condensed matter physicists—whose research relates to phases of matter—have spent much more time than particle physicists thinking about how quantum computers and simulators can help them. They have used quantum simulators to explore quantum spin liquid states [Science] and to observe a previously unobserved phase of matter called a prethermal time crystal [Science].

    “The biggest place where quantum simulators will have an impact is in discovery science, in discovering new phenomena like this that exist in nature,” says Norman Yao, an assistant professor at The University of California-Berkeley (US) and co-author on the time crystal paper.

    Quantum computers are showing promise in particle physics and astrophysics. Many physics and astrophysics researchers are using quantum computers to simulate “toy problems”—small, simple versions of much more complicated problems. They have, for example, used quantum computing to test parts of theories of quantum gravity [npj Quantum Information] or create proof-of-principle models, like models of the parton showers that emit from particle colliders [Physical Review Letters] such as the Large Hadron Collider.

    The European Organization for Nuclear Research [Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) [CERN].

    The European Organization for Nuclear Research [Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH)[CERN] map.

    CERN LHC tube in the tunnel. Credit: Maximilien Brice and Julien Marius Ordan.

    SixTRack CERN LHC particles.

    “Physicists are taking on the small problems, ones that they can solve with other ways, to try to understand how quantum computing can have an advantage,” says Roni Harnik, a scientist at Fermilab. “Learning from this, they can build a ladder of simulations, through trial and error, to more difficult problems.”

    But just which approaches will succeed, and which will lead to dead ends, remains to be seen. Estimates of how many qubits will be needed to simulate big enough problems in physics to get breakthroughs range from thousands to (more likely) millions. Many in the field expect this to be possible in the 2030s or 2040s.

    “In high-energy physics, problems like these are clearly a regime in which quantum computers will have an advantage,” says Ning Bao, associate computational scientist at DOE’s Brookhaven National Laboratory (US). “The problem is that quantum computers are still too limited in what they can do.”

    Starting with physics

    Some physicists are coming at things from a different perspective: They’re looking to physics to better understand quantum computing.

    John Preskill is a physics professor at The California Institute of Technology (US) and an early leader in the field of quantum computing. A few years ago, he and Patrick Hayden, professor of physics at Stanford University (US), showed that if you entangled two photons and threw one into a black hole, decoding the information that eventually came back out via Hawking radiation would be significantly easier than if you had used non-entangled particles. Physicists Beni Yoshida and Alexei Kitaev then came up with an explicit protocol for such decoding, and Yao went a step further, showing that protocol could also be a powerful tool in characterizing quantum computers.

    “We took something that was thought about in terms of high-energy physics and quantum information science, then thought of it as a tool that could be used in quantum computing,” Yao says.

    That sort of cross-disciplinary thinking will be key to moving the field forward, physicists say.

    “Everyone is coming into this field with different expertise,” Bao says. “From computing, or physics, or quantum information theory—everyone gets together to bring different perspectives and figure out problems. There are probably many ways of using quantum computing to study physics that we can’t predict right now, and it will just be a matter of getting the right two people in a room together.”

    See the full article here .


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    Please help promote STEM in your local schools.


    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 11:47 am on January 16, 2022 Permalink | Reply
    Tags: "Multiverse Explanation for Small Higgs Mass", , , , , , Particle Physics,   

    From Physics : “Multiverse Explanation for Small Higgs Mass” 

    About Physics

    From Physics

    January 12, 2022
    Katherine Wright

    1
    sakkmesterke/stock.adobe.com.

    A new model that assumes that a multitude of universes existed when our Universe first formed may explain why the Higgs mass is smaller than traditional models predict.

    The standard model of particle physics has been inordinately successful, providing experimental predictions that accurately describe most of our Universe’s forces and fundamental particles.

    Standard Model of Particle Physics, Quantum Diaries.

    But the model has some glaring holes. It contains no viable Dark Matter particle, it lacks an explanation for the Universe’s accelerating expansion, and it predicts a Higgs boson mass that is at least triple that measured in experiments.

    European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) ATLAS Higgs Event June 18, 2012.

    European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) CMS Higgs Event May 27, 2012.

    Now, Raffaele Tito D’Agnolo of The University of Paris-Saclay (FR) and Daniele Teresi of The European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire](CH) have developed a model that provides an explanation for the lightness of the Higgs.

    Science paper:
    Physical Review Letters

    The duo says that their model, which invokes multiverses, could also explain other conundrums, such as the observed similarity in how matter and antimatter experience strong interactions.

    As a starting point for their model, the researchers assume that at very early times in our Universe’s history there existed a multitude of universes. Each universe contained Higgs bosons with inhomogeneous masses: some regions of each universe contained a heavy Higgs boson, while others contained a very light version.

    By watching how this so-called multiverse evolved over time, the researchers found that regions having a large Higgs were unstable and collapsed in times as short as 10^−5s. That collapse, also known as crunching, destroyed those multiverse components. The only remaining universe—ours—contained a very light Higgs boson. D’Agnolo and Teresi also found another factor in their model that prevented this universe from being crunched: a symmetric strong interaction—a fundamental force of nature that occurs between subatomic particles—for matter and antimatter. This symmetry is another hole of the standard model. The team says that their model should be testable in future dark matter and hadronic experiments.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Physicists are drowning in a flood of research papers in their own fields and coping with an even larger deluge in other areas of physics. How can an active researcher stay informed about the most important developments in physics? Physics highlights a selection of papers from the Physical Review journals. In consultation with expert scientists, the editors choose these papers for their importance and/or intrinsic interest. To highlight these papers, Physics features three kinds of articles: Viewpoints are commentaries written by active researchers, who are asked to explain the results to physicists in other subfields. Focus stories are written by professional science writers in a journalistic style and are intended to be accessible to students and non-experts. Synopses are brief editor-written summaries. Physics provides a much-needed guide to the best in physics, and we welcome your comments.

     
  • richardmitnick 8:42 pm on January 15, 2022 Permalink | Reply
    Tags: "Scientists move a step closer to understanding the “cold spot” in the cosmic microwave background", , , , , , Particle Physics, The CMB Cold Spot, The Eridanus supervoid   

    From DOE’s Fermi National Accelerator Laboratory(US) : “Scientists move a step closer to understanding the “cold spot” in the cosmic microwave background” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From DOE’s Fermi National Accelerator Laboratory(US) , an enduring source of strength for the US contribution to scientific research world wide.

    January 11, 2022
    Maxwell Bernstein

    After the Big Bang, the universe, glowing brightly, was opaque and so hot that atoms could not form. Eventually cooling down to about minus 454 degrees Fahrenheit (-270 degrees Celsius), much of the energy from the Big Bang took the form of light. This afterglow, known as the cosmic microwave background [CMB], can now be seen with telescopes at microwave frequencies invisible to human eyes. It has tiny fluctuations in temperature that provide information about the early universe.

    CMB per European Space Agency(EU) Planck.

    Now scientists might have an explanation for the existence of an especially cold region in the afterglow, known as the CMB Cold Spot. Its origin has been a mystery so far but might be attributed to the largest absence of galaxies ever discovered.

    Scientists used data collected by the Dark Energy Survey to confirm the existence of one of the largest supervoids known to humanity, the Eridanus supervoid, as reported in a paper published in December 2021 [MNRAS]. This once-hypothesized but now-confirmed void in the cosmic web might be a possible cause for the anomaly in the CMB.
    _____________________________________________________________________________________
    Dark Energy Survey

    Dark Energy Camera [DECam] built at DOE’s Fermi National Accelerator Laboratory(US).
    NOIRLab National Optical Astronomy Observatory(US) Cerro Tololo Inter-American Observatory(CL) Victor M Blanco 4m Telescope which houses the Dark-Energy-Camera – DECam at Cerro Tololo, Chile at an altitude of 7200 feet.

    NOIRLab(US)NSF NOIRLab NOAO (US) Cerro Tololo Inter-American Observatory(CL) approximately 80 km to the East of La Serena, Chile, at an altitude of 2200 meters.

    Timeline of the Inflationary Universe WMAP.

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.
    _____________________________________________________________________________________

    The Eridanus supervoid

    The cosmic web is made of clusters and superclusters of galaxies. They are pulled together by the attractive force of gravity and accelerated away from each other by the repulsive force of a mysterious, not-yet-understood phenomenon called dark energy.

    Between these clusters of galaxies are voids: vast regions of space that contain fewer galaxies, and thus less ordinary matter, and less dark matter than exists within the galaxy clusters.

    Among the largest structures known to humanity, the supervoid in the constellation Eridanus is a massive, elongated, cigar-shaped void in the cosmic web that’s 1.8 billion lightyears wide and has been observed to contain about 30% less matter than the surrounding galactic region. Its center is located 2 billion lightyears from Earth, making it the dominant underdensity of matter in our galactic neighborhood.

    Mapping Dark Matter

    To make this discovery, scientists used Dark Energy Survey data to create a map of Dark Matter in the same direction as the CMB Cold Spot, by observing the effect of gravitational lensing.

    Gravitational Lensing Gravitational Lensing National Aeronautics Space Agency (US) and European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU).

    It’s a phenomenon that occurs when the paths of light are warped by the gravitational influence of Dark Matter.

    3
    The Cold Spot resides in the constellation Eridanus in the southern galactic hemisphere. The inset shows the microwave temperature map of this patch of sky, as mapped by the European Space Agency Planck satellite. The main figure depicts the map of the Dark Matter distribution created by the Dark Energy Survey team. Image: Gergö Kránicz and András Kovács.

    “This map of Dark Matter is the largest ever such map that’s been created,” said Niall Jeffrey, the scientist who worked on the construction of a dark matter map. “We have been able to map out Dark Matter over a quarter of the Southern Hemisphere.”

    Scientists previously counted the number of galaxies visible in the location of the CMB Cold Spot and found an underdensity of galaxies in that region. The new map shows there is a matching underdensity of invisible Dark Matter.

    Using voids to understand dark energy

    The Dark Energy Survey is an international effort to understand the effect dark energy has on the acceleration of the universe. It involves 300 scientists from 25 institutions in seven countries.

    The Dark Energy Survey documents hundreds of millions of galaxies, supernovae and patterns within the cosmic web, using a 570-Megapixel digital camera, called the DECam, high in the Chilean Andes. This camera’s construction and integration of components was led by the U.S. Department of Energy’s Fermi National Accelerator Laboratory.

    “We were thinking many years ago, a decade and a half at least, how would voids affect the present acceleration of the universe,” said Juan Garcia-Bellido, a cosmologist from IFT-Madrid and co-author of the paper.

    At the largest scales of the universe, there is a tug-of-war between the gravitational forces and the expansion of the universe from dark energy, making some of the voids between galactic clusters deeper.

    “Photons or particles of light enter into a void at a time before the void starts deepening and leave after the void has become deeper,” said Garcia-Bellido. “This process means that there is a net energy loss in that journey; that’s called the Integrated Sachs-Wolfe effect. When photons fall into a potential well, they gain energy, and when they come out of a potential well, they lose energy. This is the gravitational redshift effect.”

    Open questions

    Although the new result confirms that the Eridanus supervoid is gigantic, it still is not sufficient to explain the discrepancy between the predictions of the current standard cosmological model used to predict the behavior of dark energy—known as the Lambda Cold Dark Matter model—and the observed change in temperature in the Cold Spot that can be attributed to the supervoid’s effect on photons from the CMB.

    “Having the coincidence of these two individually rare structures in the cosmic web and in the CMB is basically not enough to prove causality with the scientific standard,” said András Kovács, the lead researcher on this project.

    “It is enough of a new element in the long history of the CMB Cold Spot problem that after this, people will at least be sure that there is a supervoid, which is a good thing because some people have debated that,” said Kovács.

    In short, there are two ways to think about this problem: Either the Lambda-CDM model is correct, and the CMB Cold Spot is an extreme anomaly that coincidentally has a massive supervoid in front of it, or the Lambda-CDM model is incorrect, and the Integrated Sachs-Wolfe effect is stronger in supervoids than expected.

    The latter would indicate a greater influence of dark energy on the universe and possibly faster cosmic expansion. Interestingly, this possibility is backed up by evidence from other, more distant supervoids. Moreover, the Dark Energy Survey team observed that the lensing signal from the Eridanus supervoid is slightly weaker than expected.

    “The trouble is that typical alternative models cannot explain this discrepancy either, so if true, it might mean that we do not understand something very deep about dark energy,” said Kovács.

    ______________________________________________________
    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM, denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky.
    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.
    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.
    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

    Vera Rubin measuring spectra, worked on Dark Matter(Emilio Segre Visual Archives AIP SPL).
    Dark Matter Research

    LBNL LZ Dark Matter Experiment (US) xenon detector at Sanford Underground Research Facility(US) Credit: Matt Kapust.

    Lamda Cold Dark Matter Accerated Expansion of The universe http scinotions.com the-cosmic-inflation-suggests-the-existence-of-parallel-universes. Credit: Alex Mittelmann.

    DAMA at Gran Sasso uses sodium iodide housed in copper to hunt for dark matter LNGS-INFN.

    Yale HAYSTAC axion dark matter experiment at Yale’s Wright Lab.

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB (CA) deep in Sudbury’s Creighton Mine.

    The LBNL LZ Dark Matter Experiment (US) Dark Matter project at SURF, Lead, SD, USA.

    DAMA-LIBRA Dark Matter experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS) located in the Abruzzo region of central Italy.

    DARWIN Dark Matter experiment. A design study for a next-generation, multi-ton dark matter detector in Europe at The University of Zurich [Universität Zürich](CH).

    PandaX II Dark Matter experiment at Jin-ping Underground Laboratory (CJPL) in Sichuan, China.

    Inside the Axion Dark Matter eXperiment U Washington (US) Credit : Mark Stone U. of Washington. Axion Dark Matter Experiment.
    ______________________________________________________

    See the full article here.


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    DOE’s Fermi National Accelerator (US) Laboratory Wilson Hall .

    Fermi National Accelerator Laboratory(US), located just outside Batavia, Illinois, near Chicago, is a Department of Energy (US) national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been operated by the Fermi Research Alliance, a joint venture of the University of Chicago, and the Universities Research Association (URA). Fermilab is a part of the Illinois Technology and Research Corridor.

    Fermilab’s Tevatron was a landmark particle accelerator; until the startup in 2008 of the Large Hadron Collider(CH) near Geneva, Switzerland, it was the most powerful particle accelerator in the world, accelerating antiprotons to energies of 500 GeV, and producing proton-proton collisions with energies of up to 1.6 TeV, the first accelerator to reach one “tera-electron-volt” energy. At 3.9 miles (6.3 km), it was the world’s fourth-largest particle accelerator in circumference. One of its most important achievements was the 1995 discovery of the top quark, announced by research teams using the Tevatron’s CDF and DØ detectors. It was shut down in 2011.

    In addition to high-energy collider physics, Fermilab hosts fixed-target and neutrino experiments, such as MicroBooNE (Micro Booster Neutrino Experiment), NOνA (NuMI Off-Axis νe Appearance) and SeaQuest.

    Completed neutrino experiments include MINOS (Main Injector Neutrino Oscillation Search), MINOS+, MiniBooNE and SciBooNE (SciBar Booster Neutrino Experiment).

    The MiniBooNE detector was a 40-foot (12 m) diameter sphere containing 800 tons of mineral oil lined with 1,520 phototube detectors. An estimated 1 million neutrino events were recorded each year. SciBooNE sat in the same neutrino beam as MiniBooNE but had fine-grained tracking capabilities. The NOνA experiment uses, and the MINOS experiment used, Fermilab’s NuMI (Neutrinos at the Main Injector) beam, which is an intense beam of neutrinos that travels 455 miles (732 km) through the Earth to the Soudan Mine in Minnesota and the Ash River, Minnesota, site of the NOνA far detector.

    In 2017, the ICARUS neutrino experiment was moved from CERN to Fermilab.

    In the public realm, Fermilab is home to a native prairie ecosystem restoration project and hosts many cultural events: public science lectures and symposia, classical and contemporary music concerts, folk dancing and arts galleries. The site is open from dawn to dusk to visitors who present valid photo identification.
    Asteroid 11998 Fermilab is named in honor of the laboratory.
    Weston, Illinois, was a community next to Batavia voted out of existence by its village board in 1966 to provide a site for Fermilab.

    The laboratory was founded in 1969 as the National Accelerator Laboratory; it was renamed in honor of Enrico Fermi in 1974. The laboratory’s first director was Robert Rathbun Wilson, under whom the laboratory opened ahead of time and under budget. Many of the sculptures on the site are of his creation. He is the namesake of the site’s high-rise laboratory building, whose unique shape has become the symbol for Fermilab and which is the center of activity on the campus.
    After Wilson stepped down in 1978 to protest the lack of funding for the lab, Leon M. Lederman took on the job. It was under his guidance that the original accelerator was replaced with the Tevatron, an accelerator capable of colliding protons and antiprotons at a combined energy of 1.96 TeV. Lederman stepped down in 1989. The science education center at the site was named in his honor.
    The later directors include:

    John Peoples, 1989 to 1996
    Michael S. Witherell, July 1999 to June 2005
    Piermaria Oddone, July 2005 to July 2013
    Nigel Lockyer, September 2013 to the present

    Fermilab continues to participate in the work at the Large Hadron Collider (LHC); it serves as a Tier 1 site in the Worldwide LHC Computing Grid.

    DOE’s Fermi National Accelerator Laboratory(US) campus.

    DOE’s Fermi National Accelerator Laboratory(US)/MINERvA. Photo Reidar Hahn.

    DOE’s Fermi National Accelerator Laboratory(US)DAMIC | Fermilab Cosmic Physics Center.

    DOE’s Fermi National Accelerator Laboratory(US) Muon g-2 studio. As muons race around a ring at the Muon g-2 studio, their spin axes twirl, reflecting the influence of unseen particles.

    DOE’s Fermi National Accelerator Laboratory(US) Short-Baseline Near Detector under construction.

    DOE’s Fermi National Accelerator Laboratory(US) Mu2e solenoid.

    Dark Energy Camera [DECam], built at DOE’s Fermi National Accelerator Laboratory(US).

    Fermi National Accelerator Laboratory DUNE/LBNF experiment (US) Argon tank at Sanford Underground Research Facility(US).

    FNAL Dune Far Detector.

    DOE’s Fermi National Accelerator Laboratory(US)/MicrobooNE.

    FNAL Don Lincoln.

    DOE’s Fermi National Accelerator Laboratory(US)/MINOS.

    DOE’s Fermi National Accelerator Laboratory(US) Cryomodule Testing Facility.

    DOE’s Fermi National Accelerator Laboratory(US) MINOS Far Detector.

    FNAL DUNE LBNF (US) from FNAL to SURF Lead, South Dakota, USA.

    European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire] (CH) ProtoDune.

    DOE’s Fermi National Accelerator Laboratory(US)/NOvA experiment map .

    DOE’s Fermi National Accelerator Laboratory(US) NOvA Near Detector at Batavia IL, USA.

    DOE’s Fermi National Accelerator Laboratory(US)/ICARUS.

    DOE’s Fermi National Accelerator Laboratory(US) Holometer.

    DOE’s Fermi National Accelerator Laboratory(US)LArIAT.

    DOE’s Fermi National Accelerator Laboratory(US) ICEBERG particle detector.

    FNAL Icon

     
  • richardmitnick 12:07 pm on January 15, 2022 Permalink | Reply
    Tags: Particle Physics, , , , , , , , , "From bits to qubits"   

    From Symmetry: “From bits to qubits” 

    Symmetry Mag

    From Symmetry

    01/13/22
    Sarah Charley

    1
    Illustration by Sandbox Studio, Chicago with Ana Kova.

    Quantum computers go beyond the binary.

    The first desktop computer was invented in the 1960s. But computing technology has been around for centuries, says Irfan Siddiqi, director of the Quantum Nanoelectronics Laboratory at The University of California- Berkeley (US).

    “An abacus is an ancient computer,” he says. “The materials science revolution made bits smaller, but the fundamental architecture hasn’t changed.”

    Both modern computers and abaci use basic units of information that have two possible states. In a classical computer, a binary digit (called a bit) is a 1 or a 0, represented by on-off switches in the hardware. On an abacus, a sliding bead can also be thought of as being “on” or “off,” based on its position (left or right on an abacus with horizontal rods, or up or down on an abacus with vertical ones). Bits and beads can form patterns that represent other numbers and, in the case of computers, letters and symbols.

    But what if there were even more possibilities? What if the beads of an abacus could sit in between two positions? What if the switches in a computer could consult each other before outputting a calculation?

    This is the fundamental idea behind quantum computers, which embrace the oddities of quantum mechanics to encode and process information.

    “Information in quantum mechanics is stored in very different ways than in classical mechanics, and that’s where the power comes from,” says Heather Gray, an assistant professor and particle physicist at UC Berkeley.

    Classical computer; classical mechanics

    Computing devices break down numbers into discrete components. A simple abacus could be made up of three rows: one with beads representing 100s, one with beads representing 10s, and one with beads representing 1s. In this case, the number 514 could be indicated by sliding to the right 5 beads in the 100s row, 1 bead in the 10s row, and 4 beads in the 1s row.

    The computer you may be using to read this article does something similar, counting by powers of two instead of 10s. In binary, the number 514 becomes 1000000010.

    The more complex the task, the more bits or time a computer needs to perform the calculation. To speed things up, scientists have over the years found ways to fit more and more bits into a computer. “You can now have one trillion transistors on a small silicon chip, which is a far cry from the ancient Chinese abacus,” Siddiqi says.

    But as engineers make transistors smaller and smaller, they’ve started to notice some funny effects.

    The quantum twist on computing

    Bits that behave classically are determinate: A 1 is a 1. But at very small scales, an entirely new set of physical rules comes into play.

    “We are hitting the quantum limits,” says Alberto Di Meglio, the head of CERN’s Quantum Technology Initiative. “As the scale of classic computing technology becomes smaller and smaller, quantum mechanics’ effects are not negligible anymore, and we do not want this in classic computers.”

    But quantum computers use quantum mechanics to their benefit. Rather than offering decisive answers, quantum bits, called qubits, behave like a distribution of probable values.

    Di Meglio likens qubits to undecided voters in an election. “You might know how a particular person is likely to vote, but until you actually ask them to vote, you won’t have a definite answer,” Di Meglio says.

    Qubits can be made from subatomic particles, such as electrons. Like other, similar particles, electrons have a property called spin that can exist in one of two possible states (spin-up or spin-down).

    If we think of these electrons as undecided voters, the question they are voting on is their direction of spin. Quantum computers process information while the qubits are still undecided—somewhere in between spin-up and spin-down.

    The situation becomes even more complicated when the “voters” can influence one another. This happens when two qubits are entangled. “For example, if one person votes yes, then an entangled ‘undecided’ voter will automatically vote no,” Di Meglio says. “The relationships become important, and the more voters you put together, the more chaotic it becomes.”

    When the qubits start talking to each other, each qubit can find itself in many different configurations, Siddiqi says. “An entangled array of qubits—with ‘n’ number of qubits—can exist in 2^n configurations. A quantum computer with 300 good qubits would have 2^300 possible configurations, which is more than the number of particles in the known universe.”

    With great power comes great… noise

    Entanglement allows a quantum computer to perform a complex task in a fraction of the time it would take a classical computer. But entanglement is also the quantum computer’s greatest weakness.

    “A qubit can get entangled with something else that you don’t have access to,” Siddiqi says. “Information can leave the system.”

    An electron from the computer’s power supply or a stray photon can entangle with a qubit and make it go rogue.

    “Quantum computing is not just about the number of qubits,” Di Meglio says. “You might have a quantum computer with thousands of qubits, but only a fraction are reliable.”

    Because of the problem of rogue qubits, today’s quantum computers are classified as noisy intermediate-scale quantum, or NISQ, devices. “Most quantum computers look like a physics experiment,” Gray says. “We’re very far from having one you could use at home.”

    But scientists are trying. In the future, scientists hope that they can use quantum computers to quickly search through large databases and calculate complex mathematical matrices.

    Today, physicists are already experimenting with quantum computers to simulate quantum processes, such as how particles interact with each other inside the detectors at the Large Hadron Collider. “You can do all sorts of cool things with entangled qubits,” Gray says.

    See the full article here .


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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 10:45 am on January 15, 2022 Permalink | Reply
    Tags: "Cuprates": materials that can be viewed as containing anionic copper complexes., "Newly discovered type of ‘strange metal’ could lead to deep insights", "Strange metals": A type of system where charge carriers are bosons-something that's never been seen before., , “Strange metals”: a class of materials that are related to high-temperature superconductors., Boltzmann’s constant: represents the energy produced by random thermal motion., Bosons follow very different rules from fermions., , , , Cooper pairs: a pair of electrons (or other fermions) bound together at low temperatures., Cuprates are most famous for being high-temperature superconductors meaning they conduct electricity with zero resistance at temperatures far above that of normal superconductors., Fermi liquid theory: a theoretical model of interacting fermions that describes the normal state of most metals at sufficiently low temperatures., Particle Physics, , Planck’s constant: relates to the energy of a photon (a particle of light)., This is the first time "strange metal" behavior has been seen in a bosonic system., While electrons belong to a class of particles called fermions Cooper pairs of electrons act as bosons.   

    From Brown University (US): “Newly discovered type of ‘strange metal’ could lead to deep insights” 

    From Brown University (US)

    January 12, 2022

    Kevin Stacey
    kevin_stacey@brown.edu
    401-863-3766

    A new discovery could help scientists to understand “strange metals,” a class of materials that are related to high-temperature superconductors and share fundamental quantum attributes with black holes.

    1
    Using a material called yttrium barium copper oxide arrayed with tiny holes, researchers have discovered “strange metal” behavior in a type of system where charge carriers are bosons-something that’s never been seen before.

    Scientists understand quite well how temperature affects electrical conductance in most everyday metals like copper or silver. But in recent years, researchers have turned their attention to a class of materials that do not seem to follow the traditional electrical rules. Understanding these so-called “strange metals” could provide fundamental insights into the quantum world, and potentially help scientists understand strange phenomena like high-temperature superconductivity.

    Now, a research team co-led by a Brown University physicist has added a new discovery to the “strange metal” mix. In research published in the journal Nature [“Signatures of a ‘strange metal’ in a bosonic system”], the team found “strange metal” behavior in a material in which electrical charge is carried not by electrons, but by more “wave-like” entities called Cooper pairs.

    While electrons belong to a class of particles called fermions Cooper pairs of electrons act as bosons, which follow very different rules from fermions. This is the first time “strange metal” behavior has been seen in a bosonic system, and researchers are hopeful that the discovery might be helpful in finding an explanation for how “strange metals” work — something that has eluded scientists for decades.

    “We have these two fundamentally different types of particles whose behaviors converge around a mystery,” said Jim Valles, a professor of physics at Brown and the study’s corresponding author. “What this says is that any theory to explain “strange metal” behavior can’t be specific to either type of particle. It needs to be more fundamental than that.”

    “Strange metals”

    “Strange metal” behavior was first discovered around 30 years ago in a class of materials called cuprates. These copper-oxide materials are most famous for being high-temperature superconductors, meaning they conduct electricity with zero resistance at temperatures far above that of normal superconductors. But even at temperatures above the critical temperature for superconductivity, cuprates act strangely compared to other metals.

    As their temperature increases, cuprates’ resistance increases in a strictly linear fashion. In normal metals, the resistance increases only so far, becoming constant at high temperatures in accord with what’s known as Fermi liquid theory. Resistance arises when electrons flowing in a metal bang into the metal’s vibrating atomic structure, causing them to scatter. Fermi-liquid theory sets a maximum rate at which electron scattering can occur. But strange metals don’t follow the Fermi-liquid rules, and no one is sure how they work. What scientists do know is that the temperature-resistance relationship in strange metals appears to be related to two fundamental constants of nature: Boltzmann’s constant, which represents the energy produced by random thermal motion, and Planck’s constant, which relates to the energy of a photon (a particle of light).

    “To try to understand what’s happening in these strange metals, people have applied mathematical approaches similar to those used to understand black holes,” Valles said. “So there’s some very fundamental physics happening in these materials.”

    Of bosons and fermions

    In recent years, Valles and his colleagues have been studying electrical activity in which the charge carriers are not electrons. In 1952, Nobel Laureate Leon Cooper, now a Brown professor emeritus of physics, discovered that in normal superconductors (not the high-temperature kind discovered later), electrons team up to form Cooper pairs, which can glide through an atomic lattice with no resistance. Despite being formed by two electrons, which are fermions, Cooper pairs can act as bosons.

    “Fermion and boson systems usually behave very differently,” Valles said. “Unlike individual fermions, bosons are allowed to share the same quantum state, which means they can move collectively like water molecules in the ripples of a wave.”

    In 2019, Valles and his colleagues showed that Cooper pair bosons can produce metallic behavior, meaning they can conduct electricity with some amount of resistance. That in itself was a surprising finding, the researchers say, because elements of quantum theory suggested that the phenomenon shouldn’t be possible. For this latest research, the team wanted to see if bosonic Cooper-pair metals were also “strange metals”.

    The team used a cuprate material called yttrium barium copper oxide patterned with tiny holes that induce the Cooper-pair metallic state. The team cooled the material down to just above its superconducting temperature to observe changes in its conductance. They found, like fermionic “strange metals”, a Cooper-pair metal conductance that is linear with temperature.

    The researchers say this new discovery will give theorists something new to chew on as they try to understand “strange metal” behavior.

    “It’s been a challenge for theoreticians to come up with an explanation for what we see in ‘strange metals’,” Valles said. “Our work shows that if you’re going to model charge transport in “strange metals”, that model must apply to both fermions and bosons — even though these types of particles follow fundamentally different rules.”

    Ultimately, a theory of “strange metals” could have massive implications. “Strange metal” behavior could hold the key to understanding high-temperature superconductivity, which has vast potential for things like lossless power grids and quantum computers. And because “strange metal” behavior seems to be related to fundamental constants of the universe, understanding their behavior could shed light on basic truths of how the physical world works.

    See the full article here .

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    Welcome to Brown

    Brown U Robinson Hall

    Brown University (US) is a private Ivy League research university in Providence, Rhode Island. Founded in 1764 as the College in the English Colony of Rhode Island and Providence Plantations, Brown is the seventh-oldest institution of higher education in the United States and one of the nine colonial colleges chartered before the American Revolution.

    At its foundation, Brown University was the first college in North America to accept students regardless of their religious affiliation. The university is home to the oldest applied mathematics program in the United States, the oldest engineering program in the Ivy League, and the third-oldest medical program in New England. The university was one of the early doctoral-granting U.S. institutions in the late 19th century, adding masters and doctoral studies in 1887. In 1969, Brown adopted its “Open Curriculum” after a period of student lobbying. The new curriculum eliminated mandatory “general education” distribution requirements, made students “the architects of their own syllabus” and allowed them to take any course for a grade of satisfactory (Pass) or no-credit (Fail) which is unrecorded on external transcripts. In 1971, Brown’s coordinate women’s institution, Pembroke College (US), was fully merged into the university.

    Admission is among the most selective in the United States; in 2021, the university reported an acceptance rate of 5.4%.

    The university comprises the College; the Graduate School; Alpert Medical School; the School of Engineering; the School of Public Health and the School of Professional Studies. Brown’s international programs are organized through The Watson Institute for International and Public Affairs at Brown University (US), and the university is academically affiliated with the UChicago Marine Biological Laboratory in Woods Hole, Massachusetts (US) and The Rhode Island School of Design (US). In conjunction with the Rhode Island School of Design, Brown offers undergraduate and graduate dual degree programs.

    Brown’s main campus is located in the College Hill neighborhood of Providence, Rhode Island. The university is surrounded by a federally listed architectural district with a dense concentration of Colonial-era buildings. Benefit Street, which runs along the western edge of the campus, contains one of the richest concentrations of 17th and 18th century architecture in the United States.

    As of November 2019, nine Nobel Prize winners have been affiliated with Brown as alumni, faculty, or researchers, as well as seven National Humanities Medalists and ten National Medal of Science laureates. Other notable alumni include 26 Pulitzer Prize winners, 18 billionaires, one U.S. Supreme Court Chief Justice, four U.S. Secretaries of State, 99 members of the United States Congress, 57 Rhodes Scholars, 21 MacArthur Genius Fellows, and 37 Olympic medalists.

    The foundation and the charter
    ===
    In 1761, three residents of Newport, Rhode Island, drafted a petition to the colony’s General Assembly:

    “That your Petitioners propose to open a literary institution or School for instructing young Gentlemen in the Languages, Mathematics, Geography & History, & such other branches of Knowledge as shall be desired. That for this End… it will be necessary… to erect a public Building or Buildings for the boarding of the youth & the Residence of the Professors.”

    The three petitioners were Ezra Stiles, pastor of Newport’s Second Congregational Church and future president of Yale University (US); William Ellery, Jr., future signer of the United States Declaration of Independence; and Josias Lyndon, future governor of the colony. Stiles and Ellery later served as co-authors of the college’s charter two years later. The editor of Stiles’s papers observes, “This draft of a petition connects itself with other evidence of Dr. Stiles’s project for a Collegiate Institution in Rhode Island, before the charter of what became Brown University.”

    The Philadelphia Association of Baptist Churches were also interested in establishing a college in Rhode Island—home of the mother church of their denomination. At the time, the Baptists were unrepresented among the colonial colleges; the Congregationalists had Harvard University (US) and Yale, the Presbyterians had the College of New Jersey (later Princeton University (US)), and the Episcopalians had The William & Mary College (US) and King’s College (later Columbia University(US)). Isaac Backus, a historian of the New England Baptists and an inaugural trustee of Brown, wrote of the October 1762 resolution taken at Philadelphia:

    “The Philadelphia Association obtained such an acquaintance with our affairs, as to bring them to an apprehension that it was practicable and expedient to erect a college in the Colony of Rhode-Island, under the chief direction of the Baptists; … Mr. James Manning, who took his first degree in New-Jersey college in September, 1762, was esteemed a suitable leader in this important work.”

    James Manning arrived at Newport in July 1763 and was introduced to Stiles, who agreed to write the charter for the college. Stiles’ first draft was read to the General Assembly in August 1763 and rejected by Baptist members who worried that their denomination would be underrepresented in the College Board of Fellows. A revised charter written by Stiles and Ellery was adopted by the Rhode Island General Assembly on March 3, 1764, in East Greenwich.

    In September 1764, the inaugural meeting of the corporation—the college’s governing body—was held in Newport’s Old Colony House. Governor Stephen Hopkins was chosen chancellor, former and future governor Samuel Ward vice chancellor, John Tillinghast treasurer, and Thomas Eyres secretary. The charter stipulated that the board of trustees should be composed of 22 Baptists, five Quakers, five Episcopalians, and four Congregationalists. Of the 12 Fellows, eight should be Baptists—including the college president—”and the rest indifferently of any or all Denominations.”

    At the time of its creation, Brown’s charter was a uniquely progressive document. Other colleges had curricular strictures against opposing doctrines, while Brown’s charter asserted, “Sectarian differences of opinions, shall not make any Part of the Public and Classical Instruction.” The document additionally “recognized more broadly and fundamentally than any other [university charter] the principle of denominational cooperation.” The oft-repeated statement that Brown’s charter alone prohibited a religious test for College membership is inaccurate; other college charters were similarly liberal in that particular.

    The college was founded as Rhode Island College, at the site of the First Baptist Church in Warren, Rhode Island. James Manning was sworn in as the college’s first president in 1765 and remained in the role until 1791. In 1766, the college authorized Rev. Morgan Edwards to travel to Europe to “solicit Benefactions for this Institution.” During his year-and-a-half stay in the British Isles, the reverend secured funding from benefactors including Thomas Penn and Benjamin Franklin.

    In 1770, the college moved from Warren to Providence. To establish a campus, John and Moses Brown purchased a four-acre lot on the crest of College Hill on behalf of the school. The majority of the property fell within the bounds of the original home lot of Chad Brown, an ancestor of the Browns and one of the original proprietors of Providence Plantations. After the college was relocated to the city, work began on constructing its first building.

    A building committee, organized by the corporation, developed plans for the college’s first purpose-built edifice, finalizing a design on February 9, 1770. The subsequent structure, referred to as “The College Edifice” and later as University Hall, may have been modeled on Nassau Hall, built 14 years prior at the College of New Jersey. President Manning, an active member of the building process, was educated at Princeton and might have suggested that Brown’s first building resemble that of his alma mater.

    The College

    Founded in 1764, the college is Brown’s oldest school. About 7,200 undergraduate students are enrolled in the college, and 81 concentrations are offered. For the graduating class of 2020 the most popular concentrations were Computer Science; Economics; Biology; History; Applied Mathematics; International Relations and Political Science. A quarter of Brown undergraduates complete more than one concentration before graduating. If the existing programs do not align with their intended curricular interests, undergraduates may design and pursue independent concentrations.

    35 percent of undergraduates pursue graduate or professional study immediately, 60 percent within 5 years, and 80 percent within 10 years. For the Class of 2009, 56 percent of all undergraduate alumni have since earned graduate degrees. Among undergraduate alumni who go on to receive graduate degrees, the most common degrees earned are J.D. (16%), M.D. (14%), M.A. (14%), M.Sc. (14%), and Ph.D. (11%). The most common institutions from which undergraduate alumni earn graduate degrees are Brown University, Columbia University, and Harvard University.

    The highest fields of employment for undergraduate alumni ten years after graduation are education and higher education (15%), medicine (9%), business and finance (9%), law (8%), and computing and technology (7%).

    Brown and RISD

    Since its 1893 relocation to College Hill, Rhode Island School of Design (RISD) has bordered Brown to its west. Since 1900, Brown and RISD students have been able to cross-register at the two institutions, with Brown students permitted to take as many as four courses at RISD to count towards their Brown degree. The two institutions partner to provide various student-life services and the two student bodies compose a synergy in the College Hill cultural scene.

    Rankings

    Brown University is accredited by the New England Commission of Higher Education. For their 2021 rankings, The Wall Street Journal/Times Higher Education ranked Brown 5th in the Best Colleges 2021 edition.

    The Forbes Magazine annual ranking of America’s Top Colleges 2021—which ranked 600 research universities, liberal arts colleges and service academies—ranked Brown 26th overall and 23rd among universities.

    U.S. News & World Report ranked Brown 14th among national universities in its 2021 edition.[162] The 2021 edition also ranked Brown 1st for undergraduate teaching, 20th in Most Innovative Schools, and 18th in Best Value Schools.

    Washington Monthly ranked Brown 37th in 2020 among 389 national universities in the U.S. based on its contribution to the public good, as measured by social mobility, research, and promoting public service.

    For 2020, U.S. News & World Report ranks Brown 102nd globally.

    In 2014, Forbes Magazine ranked Brown 7th on its list of “America’s Most Entrepreneurial Universities.” The Forbes analysis looked at the ratio of “alumni and students who have identified themselves as founders and business owners on LinkedIn” and the total number of alumni and students.

    LinkedIn particularized the Forbes rankings, placing Brown third (between The Massachusetts Institute of Technology (US) and Princeton) among “Best Undergraduate Universities for Software Developers at Startups.” LinkedIn’s methodology involved a career-path examination of “millions of alumni profiles” in its membership database.

    In 2020, U.S. News ranked Brown’s Warren Alpert Medical School the 9th most selective in the country, with an acceptance rate of 2.8 percent.

    According to 2020 data from The Department of Education (US), the median starting salary of Brown computer science graduates was the highest in the United States.

    In 2020, Brown produced the second-highest number of Fulbright winners. For the three years prior, the university produced the most Fulbright winners of any university in the nation.

    Research

    Brown is member of The Association of American Universities (US) since 1933 and is classified among “R1: Doctoral Universities – Very High Research Activity”. In FY 2017, Brown spent $212.3 million on research and was ranked 103rd in the United States by total R&D expenditure by The National Science Foundation (US).

     
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