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  • richardmitnick 3:00 pm on November 22, 2014 Permalink | Reply
    Tags: , , , , , Particle Physics,   

    From Triumf: “LHCb Experiment Confirms TRIUMF Prediction” 

    On Wednesday, November 19th, the LHCb collaboration at CERN’s Large Hadron Collider (LHC) announced the discovery of two new particles in the baryon family. The particles, known as the Xi_b’- and Xi_b*-, were predicted to exist by the quark model but had never been seen before.

    CERN LHCb New
    LHCb at CERN

    Randy Lewis, York University, and Richard Woloshyn (photographed), TRIUMF, submitted a paper together in 2009, “Bottom baryons from a dynamical lattice QCD simulation,” in which the masses of Xi_b’- and Xi_b* were predicted. This paper, among the eight theoretical papers cited in the LHCb collaboration report submitted to the Physical Review Letters, offered the LHCb researchers a light in the path of discovery.

    rw
    Richard Woloshyn

    “Theoretical and experimental physics complement each other in an important way,” said Petr Navratil, Head of Theory Department at TRIUMF. “Richard’s work illustrates how theoretical predictions motivate experimental efforts. Experimental results then provide feedback to improve the theoretical understanding.”

    The new particles are baryons made from three quarks bound together by the strong force. The types of quarks are different, though: the new Xib particles both contain one beauty (b), one strange (s), and one down (d) quark. Thanks to the heavyweight b quarks, the baryons are more than six times as massive as the proton. But the particles are more than just the sum of their parts: their mass also depends on how they are configured. Each of the quarks has an attribute called “spin“. In the Xi_b’- state, the spins of the two lighter quarks point in opposite directions, whereas in the Xi_b*- state they are aligned. This difference makes the Xi_b*- a little heavier.

    “Nature was kind and gave us two particles for the price of one,” said
    Matthew Charles of the CNRS’s LPNHE laboratory at Paris VI University.

    “The Xi_b’- is very close in mass to the sum of its decay products: if it had been just a little lighter, we wouldn’t have seen it at all using the decay signature that we were looking for.”

    “This is a very exciting result. Thanks to LHCb’s excellent hadron identification, which is unique among the LHC experiments, we were able to separate a very clean and strong signal from the background,” said Steven Blusk from Syracuse University in New York. “It demonstrates once again the sensitivity and how precise the LHCb detector is.”

    “I am happy that LHCb cites our work and that it appears on the broader stage, ” said Richard Woloshyn, “It shows the work we do here at TRIUMF and in Canada is important.”

    As well as the masses of these particles, the LHCb team studied their relative production rates, their widths – a measure of how unstable they are – and other details of their decays. The results match up with predictions based on the theory of Quantum Chromodynamics (QCD). QCD is part of the Standard Model of particle physics, the theory that describes the fundamental particles of matter, how they interact and the forces between them.

    sm
    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    “Our approach was based directly on QCD. These results give us confidence and show that the theory is adequate to deal with any measurement and to predict the outcomes of experiments,” said Richard.

    “This success is a reminder of TRIUMF’s leadership role in theoretical physics. Richard has been using the computational method called lattice QCD to make important contributions for many years, and I am one of several people who learned lattice QCD by spending time at TRIUMF with Richard,” said Randy Lewis.

    Richard admits that when he first saw the InterActions news release he did not expect it to be related to one of his theoretical ‘discoveries’ and set it aside to read later. It wasn’t until he saw the CBC headline, “New subatomic particles predicted by Canadians found at CERN” that he knew of his part in the discovery.

    See the full article here..

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  • richardmitnick 12:27 pm on November 20, 2014 Permalink | Reply
    Tags: , , , , , Particle Physics   

    From CERN: “CERN makes public first data of LHC experiments” 

    CERN New Masthead

    20 Nov 2014
    Cian O’Luanaigh

    CERN today launched its Open Data Portal where data from real collision events, produced by experiments at the Large Hadron Collider (LHC) will for the first time be made openly available to all. It is expected that these data will be of high value for the research community, and also be used for education purposes.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    cern

    “Launching the CERN Open Data Portal is an important step for our Organization. Data from the LHC programme are among the most precious assets of the LHC experiments, that today we start sharing openly with the world. We hope these open data will support and inspire the global research community, including students and citizen scientists,” says CERN Director-General Rolf Heuer.

    The principle of openness is enshrined in CERN’s founding Convention, and all LHC publications have been published Open Access, free for all to read and re-use. Widening the scope, the LHC collaborations recently approved Open Data policies and will release collision data over the coming years.

    The first high-level and analysable collision data openly released come from the CMS experiment and were originally collected in 2010 during the first LHC run. This data set is now publicly available on the CERN Open Data Portal. Open source software to read and analyse the data is also available, together with the corresponding documentation. The CMS collaboration is committed to releasing its data three years after collection, after they have been thoroughly studied by the collaboration.

    CERN CMS New
    CMS

    “This is all new and we are curious to see how the data will be re-used,” says CMS data preservation coordinator Kati Lassila-Perini. “We’ve prepared tools and examples of different levels of complexity from simplified analysis to ready-to-use online applications. We hope these examples will stimulate the creativity of external users.”

    In parallel, the CERN Open Data Portal gives access to additional event data sets from the ALICE, ATLAS, CMS and LHCb collaborations, which have been specifically prepared for educational purposes, such as the international masterclasses in particle physics benefiting over ten thousand high-school students every year. These resources are accompanied by visualisation tools.

    CERN ALICE New
    ALICE

    CERN ATLAS New
    ATLAS

    CERN LHCb New
    LHCb

    “Our own data policy foresees data preservation and its sharing. We have seen that students are fascinated by being able to analyse LHC data in the past and so, we are very happy to take the first steps and make available some selected data for education” says Silvia Amerio, data preservation coordinator of the LHCb experiment.

    “The development of this Open Data Portal represents a first milestone in our mission to serve our users in preserving and sharing their research materials. It will ensure that the data and tools can be accessed and used, now and in the future,” says Tim Smith of the CERN IT Department.

    All data on OpenData.cern.ch are shared under a Creative Commons CC0 public domain dedication; data and software are assigned unique DOI identifiers to make them citable in scientific articles; and software is released under open source licenses. The CERN Open Data Portal is built on the open-source Invenio Digital Library software, which powers other CERN Open Science tools and initiatives.

    See the full article here.

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  • richardmitnick 9:42 am on November 19, 2014 Permalink | Reply
    Tags: , , , , , Particle Physics   

    From LHCb at CERN: “LHCb experiment observes two new baryon particles never seen before” 

    CERN New Masthead

    19 Nov 2014
    No Writer Credit

    graph

    Geneva 19 November 2014. Today the collaboration for the LHCb experiment at CERN’s Large Hadron Collider announced the discovery of two new particles in the baryon family. The particles, known as the Xi_b’- and Xi_b*-, were predicted to exist by the quark model but had never been seen before. A related particle, the Xi_b*0, was found by the CMS experiment at CERN in 2012. The LHCb collaboration submitted a paper reporting the finding to Physical Review Letters.

    CERN LHCb New
    LHCb at CERN

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    Like the well-known protons that the LHC accelerates, the new particles are baryons made from three quarks bound together by the strong force. The types of quarks are different, though: the new X_ib particles both contain one beauty (b), one strange (s), and one down (d) quark. Thanks to the heavyweight b quarks, they are more than six times as massive as the proton. But the particles are more than just the sum of their parts: their mass also depends on how they are configured. Each of the quarks has an attribute called “spin“. In the Xi_b’- state, the spins of the two lighter quarks point in opposite directions, whereas in the Xi_b*- state they are aligned. This difference makes the Xi_b*- a little heavier.

    “Nature was kind and gave us two particles for the price of one,” said Matthew Charles of the CNRS’s LPNHE laboratory at Paris VI University. “The Xi_b’- is very close in mass to the sum of its decay products: if it had been just a little lighter, we wouldn’t have seen it at all using the decay signature that we were looking for.”

    “This is a very exciting result. Thanks to LHCb’s excellent hadron identification, which is unique among the LHC experiments, we were able to separate a very clean and strong signal from the background,” said Steven Blusk from Syracuse University in New York. “It demonstrates once again the sensitivity and how precise the LHCb detector is.”

    As well as the masses of these particles, the research team studied their relative production rates, their widths – a measure of how unstable they are – and other details of their decays. The results match up with predictions based on the theory of Quantum Chromodynamics (QCD).

    QCD is part of the Standard Model of particle physics, the theory that describes the fundamental particles of matter, how they interact and the forces between them. Testing QCD at high precision is a key to refine our understanding of quark dynamics, models of which are tremendously difficult to calculate.

    sm
    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    “If we want to find new physics beyond the Standard Model, we need first to have a sharp picture,” said LHCb’s physics coordinator Patrick Koppenburg from Nikhef Institute in Amsterdam. “Such high precision studies will help us to differentiate between Standard Model effects and anything new or unexpected in the future.”

    The measurements were made with the data taken at the LHC during 2011-2012. The LHC is currently being prepared – after its first long shutdown – to operate at higher energies and with more intense beams. It is scheduled to restart by spring 2015.

    Further information

    Caption diagram : The mass difference spectrum: the LHCb result shows strong evidence of the existence of two new particles the Xi_b’- (first peak) and Xi_b*- (second peak), with the very high-level confidence of 10 sigma. The black points are the signal sample and the hatched red histogram is a control sample. The blue curve represents a model including the two new particles, fitted to the data. Delta_m is the difference between the mass of the Xi_b0 pi- pair and the sum of the individual masses of the Xi_b0 and pi-.. INSET: Detail of the Xi_b’- region plotted with a finer binning.

    Link to the paper on Arxiv: http://arxiv.org/abs/1411.4849
    More about the result on LHCb’s collaboration website: http://lhcb-public.web.cern.ch/lhcb-public/Welcome.html#StrBeaBa
    Observation of a new Xi_b*0 beauty particle, on CMS’ collaboration website: http://cms.web.cern.ch/news/observation-new-xib0-beauty-particle
    Footnote(s)

    1. CERN, the European Organization for Nuclear Research, is the world’s leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Israel, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a Candidate for Accession. Serbia is an Associate Member in the pre-stage to Membership. India, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer Status.

    See the full article here.
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  • richardmitnick 1:14 pm on November 18, 2014 Permalink | Reply
    Tags: , , Larry McLerran, Particle Physics,   

    From BNL: “New Matter, Mathematical Models & Larry McLerran” 

    Brookhaven Lab

    November 18, 2014
    Joe Gettler

    American Physical Society to Honor Brookhaven Lab Physicist Larry McLerran With Feshbach Prize

    lm
    Larry McLerran

    With mathematical models, and some very good company both young and old, Larry McLerran’s decades-long quest to make sense of the laws governing the Universe’s most basic building blocks of matter has taken him from the United States’ West Coast to its East, and even as far as the Hunan province in central China. McLerran earned a Ph.D. in physics nearly forty years ago and today he’s a senior scientist at the Department of Energy’s Brookhaven National Laboratory (BNL) and Theory Group leader for the RIKEN BNL Research Center (RBRC). Now, the American Physical Society (APS) will recognize McLerran for his pursuits, when he is presented with the APS’ Feshbach Prize for outstanding lifetime achievements in nuclear physics theory.

    The APS will present McLerran with its Feshbach Prize during the annual APS meeting in Baltimore, Maryland, in April 2015. McLerran was chosen to receive this honor “for his pioneering study of quantum chromodynamics at high energy density and laying the theoretical foundations of experimental ultrarelativistic heavy ion collisions. His work has been a crucial guide to experiments at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider, and he has mentored a generation of young theorists.”

    BNL RHIC
    RHIC at BNL

    CERN LHC Grand Tunnel
    LHC at CERN

    “Over the years, I’ve worked with computers, pencils, chalk, and—most importantly—talented colleagues to figure out why the Universe behaves the way it does,” McLerran said. “I’m honored that my colleagues in the American Physical Society are recognizing me with this Feshbach Prize.”

    What’s the [New] Matter?

    “From tiny, short-lived subatomic particles to mysterious dark energy, the matter of our Universe forms beautiful, complex systems with many simple patterns and rules we understand very little about. There are great opportunities for discovery.”
    — Larry McLerran

    As a theoretical physicist, McLerran uses—and develops—complex mathematical models to figure out and explain why the Universe works the way it does. In particular, he probes the Universe within the scope of the theory of quantum chromodynamics, which describes the “strong” interactions among subatomic quarks and gluons that are naturally confined in protons and neutrons.

    In the early ’80s, McLerran and his colleague Ben Svetitsky of Tel Aviv University in Israel used computers that were powerful at the time and massive quantities of randomly generated numbers to do the first Monte Carlo simulation for high-temperature quantum chromodynamics. Together, they found a transition when those naturally confined quarks and gluons become free, no longer held captive by the strong force in the larger protons and neutrons. McLerran was among the first to propose that quark-gluon plasma—a blend of unbound quarks and gluons—could be produced by colliding heavy ions with high energies. Experimentalists later confirmed this at the Relativistic Heavy Ion Collider at Brookhaven Lab, where they produced quark-gluon plasma from colliding gold ions, yet they were surprised to learn quark-gluon plasma was a free-flowing liquid, not a gas as most theorists predicted.

    Many of McLerran’s more recent contributions and achievements resulted from collaborations with his colleagues in the Physics Department’s Nuclear Theory Group—which aims to understand the fundamental structure of matter—and RBRC, a research center at Brookhaven Lab funded primarily by the Japanese RIKEN Laboratory for researchers to develop theoretical and computational physics, and to analyze data produced from particle collisions at RHIC.

    “Since coming to Brookhaven, Larry has helped build one of the best nuclear theory groups in the world. And as theory group leader for the RIKEN BNL Research Center, he has inspired and mentored a generation of outstanding nuclear theorists in the U.S. and abroad,” Nuclear Theory Group Leader Raju Venugopalan said. “In my view, Larry’s outsized creative achievements and tremendous impact make him a guaranteed ‘slam-dunk’ case for a lifetime achievement award like this APS Feshbach Prize.”

    Venugopalan and McLerran invented the idea of a kind of matter called “color glass condensate” that controls the limits of quantum chromodynamics at high energies. McLerran and Rob Pisarski of the Nuclear Theory Group and RBRC invented the concept of “quarkyonic matter,” which has properties of both free quarks and other confined particles called mesons and baryons. And with the Nuclear Theory Group’s Dmitri Kharzeev and postdoc Harmen Warringa, McLerran made a seminal contribution to a theory called the “chiral magnetic effect.”

    McLerran also worked with Alex Kovner of the University of Connecticut and Heribert Weigert at the University of Cape Town in South Africa to invent the theory for yet another new form of matter, called “glasma,” which makes the transition between the color glass condensate and quark-gluon plasma in collisions among strongly interacting particles. Today, McLerran is focused on determining the properties of glasma.

    “From tiny, short-lived subatomic particles to mysterious dark energy, the matter of our Universe forms beautiful, complex systems with many simple patterns and rules we understand very little about. There are great opportunities for discovery,” said McLerran.

    McLerran’s Major Milestones

    McLerran earned a Ph.D. in physics from the University of Washington in 1975. He worked as a research associate at the Massachusetts Institute of Technology from 1975 to 1978, and then at Stanford Linear Accelerator Center from 1978 until 1980. From 1980 to 1984, he was an assistant and associate professor at the University of Washington, and from 1984 to 1989 a scientist at Fermi National Accelerator Laboratory. He taught as a professor at the University of Minnesota from 1988 to 2000, while also serving as a member and director of its Theoretical Physics Institute.

    In 1999, McLerran arrived at Brookhaven Lab as a senior scientist and led the Nuclear Theory Group until 2004. He took on his current role as the Theory Group Leader for the RIKEN BNL Research Center in 2003.

    McLerran has received a number of awards during his career, including a Brookhaven Science and Technology Award in FY2007—one of the Laboratory’s most distinguished prizes awarded for the exceptional nature of an employee’s contributions as well as the level of difficulty and benefit for Brookhaven.

    McLerran is a fellow of the American Physical Society and a foreign member of the Finnish Academy of Arts and Sciences. He was an Alexander Sloan Foundation Fellow; awarded the Alexander Humboldt prize in 1988; received the Hans Jensen prize at the University of Heidelberg in 2009, where he is a Jensen Professor of Theoretical Physics; and granted an honorary Ph.D. from Central China Normal University in 2011. He is currently the university’s Liu Lian Shou Professor of Theoretical Physics.

    Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.. Now, the American Physical Society (APS) will recognize McLerran for his pursuits, when he is presented with the APS’ Feshbach Prize for outstanding lifetime achievements in nuclear physics theory.

    The APS will present McLerran with its Feshbach Prize during the annual APS meeting in Baltimore, Maryland, in April 2015. McLerran was chosen to receive this honor “for his pioneering study of quantum chromodynamics at high energy density and laying the theoretical foundations of experimental ultrarelativistic heavy ion collisions. His work has been a crucial guide to experiments at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider, and he has mentored a generation of young theorists.”

    “Over the years, I’ve worked with computers, pencils, chalk, and—most importantly—talented colleagues to figure out why the Universe behaves the way it does,” McLerran said. “I’m honored that my colleagues in the American Physical Society are recognizing me with this Feshbach Prize.”
    What’s the [New] Matter?

    “From tiny, short-lived subatomic particles to mysterious dark energy, the matter of our Universe forms beautiful, complex systems with many simple patterns and rules we understand very little about. There are great opportunities for discovery.”
    — Larry McLerran

    As a theoretical physicist, McLerran uses—and develops—complex mathematical models to figure out and explain why the Universe works the way it does. In particular, he probes the Universe within the scope of the theory of quantum chromodynamics, which describes the “strong” interactions among subatomic quarks and gluons that are naturally confined in protons and neutrons.

    In the early ’80s, McLerran and his colleague Ben Svetitsky of Tel Aviv University in Israel used computers that were powerful at the time and massive quantities of randomly generated numbers to do the first Monte Carlo simulation for high-temperature quantum chromodynamics. Together, they found a transition when those naturally confined quarks and gluons become free, no longer held captive by the strong force in the larger protons and neutrons. McLerran was among the first to propose that quark-gluon plasma—a blend of unbound quarks and gluons—could be produced by colliding heavy ions with high energies. Experimentalists later confirmed this at the Relativistic Heavy Ion Collider at Brookhaven Lab, where they produced quark-gluon plasma from colliding gold ions, yet they were surprised to learn quark-gluon plasma was a free-flowing liquid, not a gas as most theorists predicted.

    Many of McLerran’s more recent contributions and achievements resulted from collaborations with his colleagues in the Physics Department’s Nuclear Theory Group—which aims to understand the fundamental structure of matter—and RBRC, a research center at Brookhaven Lab funded primarily by the Japanese RIKEN Laboratory for researchers to develop theoretical and computational physics, and to analyze data produced from particle collisions at RHIC.

    “Since coming to Brookhaven, Larry has helped build one of the best nuclear theory groups in the world. And as theory group leader for the RIKEN BNL Research Center, he has inspired and mentored a generation of outstanding nuclear theorists in the U.S. and abroad,” Nuclear Theory Group Leader Raju Venugopalan said. “In my view, Larry’s outsized creative achievements and tremendous impact make him a guaranteed ‘slam-dunk’ case for a lifetime achievement award like this APS Feshbach Prize.”

    Venugopalan and McLerran invented the idea of a kind of matter called “color glass condensate” that controls the limits of quantum chromodynamics at high energies. McLerran and Rob Pisarski of the Nuclear Theory Group and RBRC invented the concept of “quarkyonic matter,” which has properties of both free quarks and other confined particles called mesons and baryons. And with the Nuclear Theory Group’s Dmitri Kharzeev and postdoc Harmen Warringa, McLerran made a seminal contribution to a theory called the “chiral magnetic effect.”

    McLerran also worked with Alex Kovner of the University of Connecticut and Heribert Weigert at the University of Cape Town in South Africa to invent the theory for yet another new form of matter, called “glasma,” which makes the transition between the color glass condensate and quark-gluon plasma in collisions among strongly interacting particles. Today, McLerran is focused on determining the properties of glasma.

    “From tiny, short-lived subatomic particles to mysterious dark energy, the matter of our Universe forms beautiful, complex systems with many simple patterns and rules we understand very little about. There are great opportunities for discovery,” said McLerran.

    McLerran’s Major Milestones

    McLerran earned a Ph.D. in physics from the University of Washington in 1975. He worked as a research associate at the Massachusetts Institute of Technology from 1975 to 1978, and then at Stanford Linear Accelerator Center from 1978 until 1980. From 1980 to 1984, he was an assistant and associate professor at the University of Washington, and from 1984 to 1989 a scientist at Fermi National Accelerator Laboratory. He taught as a professor at the University of Minnesota from 1988 to 2000, while also serving as a member and director of its Theoretical Physics Institute.

    In 1999, McLerran arrived at Brookhaven Lab as a senior scientist and led the Nuclear Theory Group until 2004. He took on his current role as the Theory Group Leader for the RIKEN BNL Research Center in 2003.

    McLerran has received a number of awards during his career, including a Brookhaven Science and Technology Award in FY2007—one of the Laboratory’s most distinguished prizes awarded for the exceptional nature of an employee’s contributions as well as the level of difficulty and benefit for Brookhaven.

    McLerran is a fellow of the American Physical Society and a foreign member of the Finnish Academy of Arts and Sciences. He was an Alexander Sloan Foundation Fellow; awarded the Alexander Humboldt prize in 1988; received the Hans Jensen prize at the University of Heidelberg in 2009, where he is a Jensen Professor of Theoretical Physics; and granted an honorary Ph.D. from Central China Normal University in 2011. He is currently the university’s Liu Lian Shou Professor of Theoretical Physics.

    Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

    See the full article here.

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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 10:20 am on November 14, 2014 Permalink | Reply
    Tags: , , , , , , Particle Physics   

    From FNAL- “Frontier Science Result: CMS Origin of the smallest masses” 


    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    Friday, Nov. 14, 2014
    Jim Pivarski

    Since the discovery of the Higgs boson two years ago, about 80 analyses have helped to pin down its properties. Today, we know that it does not spin, that it is mirror-symmetric, and that it decays into pairs of W bosons, pairs of Z bosons, pairs of tau leptons, and pairs of photons (through a pair of short-lived top quarks). There are even weak hints at a fifth decay mode: decays into pairs of b quarks. All of these results are in agreement with expectations for a Standard Model Higgs boson, but they are still coarse measurements with significant uncertainties.

    sm
    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    To say that this boson is a Standard Model Higgs is to say that it is exactly the particle that was predicted in 1964. That leaves a lot of room for surprises. Without interference from new phenomena, the rate that this boson decays into particle-antiparticle pairs would be proportional to the square of the mass of the particle-antiparticle pairs. The best way to check the proportionality of something is to look at it on an extreme range. Since the Higgs is believed to give mass to everything from 0.0005-GeV electrons to 173-GeV top quarks, there’s plenty of room to check.

    dots
    Muons (red) are 18 times lighter than tau leptons (blue), so we expect Higgs decays to muon pairs to be about 300 times less common than Higgs decays to tau pairs.

    The highest decay rates are easiest to detect, so only the heaviest particle-antiparticle pairs have been tested so far. The lightest particle-antiparticle decay that has been observed is Higgs to pairs of tau leptons, which are 1.8 GeV each. The next-lighter final state that could be observed is Higgs to pairs of muons, which are 0.1 GeV each. By the expected scaling, Higgs to muon pairs should be 300 times less common. However, muons are easy to detect and clearly identify, so they make a good target.

    Even if you combine all the LHC data collected so far, it would not be enough to see evidence of this decay mode. However, the LHC is scheduled to restart next spring at almost twice its former energy. Higher energy and more intense beams would produce more Higgs bosons, making a future detection of Higgs to muon pairs possible.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    To prepare for such a discovery and find potential problems early, CMS scientists searched for Higgs to muon pairs in the current data set. They didn’t find any, but they did establish that no more than 0.16 percent of Higgs bosons decay into muons, only a factor of 7 from the expected number, and then they used these results to project sensitivity in future LHC data. Incidentally, the Higgs boson is the first particle known to decay into tau lepton pairs much more (6.3 percent) than muon pairs (0.023 percent). All other particles decay into taus and muons almost equally.

    CERN CMS New
    CMS in the LHC at CERN

    They also searched for Higgs decays into electrons, the lighter cousin of muons and tau leptons. Since electrons are 200 times lighter than muons, Higgs to electron pairs is expected only 0.00000051 percent of the time. None were found, though an observation would been an exciting surprise!

    See the full article here.

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  • richardmitnick 3:06 pm on November 13, 2014 Permalink | Reply
    Tags: , , , , , Particle Physics   

    From FNAL- “Frontier Science Result: DZero Sharing the momentum” 


    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    Thursday, Nov. 13, 2014
    Leo Bellantoni

    The parts inside of a proton are called, in a not terribly imaginative terminology, partons. The partons that we tend to think of first and foremost are quarks — two up quarks and a down quark in each proton — but there are other kinds of partons as well.

    Each parton in a moving proton carries some momentum, which is a fraction of the total momentum of the proton. Because the partons interact with each other constantly, the momentum of a parton keeps changing. So at any particular time, there is some probability that the down quark is carrying, say, half the momentum of the proton, and later it might be a quarter of the total momentum. The fraction is called x. When the down quark is carrying half the momentum of the proton, it has an x of 0.5. These probabilities are key ingredients in calculating what happens in a hadron collider and can only be deduced from experiment.

    olot
    This plot shows the probabilities of finding up and down quarks with different fractions of a proton’s momentum. The vertical axis is arbitrary and different for the two curves. No image credit.

    The figure shows plots of the probabilities of finding up or down quarks at particular values of x. The vertical scale is a little arbitrary, but that won’t matter for us. Notice how the curve for down quarks, in blue, peaks at the left, at low values of x. That means that at any instant, the down quark tends to have a relatively small fraction of the proton’s momentum. The up quark curve, in red, has a ledge, a sort of bump in the generally downward slope at x around 0.2 or so. That means that the chances of an up quark having more momentum than a down quark are really pretty good.

    When a proton with a higher-momentum up quark hits an antiproton with a lower-momentum down antiquark, then these two partons can form a W+ boson, and that W+ boson is headed in the direction of the higher momentum. In a collision of an up antiquark and a down quark, a W- boson can be created that tends to travel in the antiproton direction. Things get a little more complicated when a W+ boson decays to a positron or a W- decays to electrons, but the positron and electron directions still carry information about the x-values of the colliding quarks.

    So the curves in the figure can be measured — or measured better — by looking at events in the Tevatron where a W+ or W- is produced and decays into a positron or electron and measuring the difference, or asymmetry, in the final electron and positron directions.

    DZero has measured the asymmetry in electron and positron directions relative to the direction of the proton’s motion when it collides with antiprotons in the Tevatron. The result is the most precise measurement of this asymmetry to date and provides important information about the momentum of the partons of protons. That information is critical in predicting what happens in all sorts of collisions involving protons, such as those at neutrino and LHC experiments.

    See the full article here.

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    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.

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  • richardmitnick 1:58 pm on November 12, 2014 Permalink | Reply
    Tags: , , Fermilab Neutrino Division, , , Particle Physics   

    From FNAL: “From the Neutrino Division – The new Neutrino Division” 


    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    Wednesday, Nov. 12, 2014

    rc
    Regina Rameika, head of the Neutrino Division, wrote this column.

    Neutrino experiments have played a big part in Fermilab’s 47-year history, and we are now working to make them an even bigger part of Fermilab’s future. As we plan for the next 40 years, we strive to fulfill an important element of the laboratory’s vision: to lead the world in neutrino science with particle accelerators. To enable this vision, in July Director Lockyer announced the formation of a Neutrino Division at Fermilab.

    The initial goal of this new organization is to provide a visible home with administrative and technical support for the laboratory’s current and planned neutrino experiments. In October, about 70 staff, guest scientists and international fellows became the first members of the new division.

    The organization is starting out small, with two very well-defined tasks. The first is to focus on operating the experiments in the NuMI and Booster neutrino beams: MicroBooNE, MINERvA, MINOS+ and NOvA. The second, aligning ourselves with the P5 plan, is to develop in a coordinated way a world-leading program of short- and long-baseline neutrino experiments. The division will host the Long-Baseline Neutrino Facility (LBNF) project team as well as the staff and user community who are joining this effort.

    The Neutrino Division is beginning to grow a new group focused on optimizing beam designs and modeling for existing as well as future neutrino beams. It has a Technical Support Department, including a team of engineers specializing in cryogenic systems to operate and design liquid-argon neutrino detectors, which are the key elements in both the short-baseline and LBNF programs. We expect the engineering team to grow as the new projects mature and require more design effort. The Technical Support Department also includes the Operations Support Group, which supports the current and future experiments either directly or as experiment liaisons with the other divisions and sections of the laboratory.

    As a new division, we are learning many of the complexities involved in running an organization, including managing personnel with the new FermiWorks system, planning budgets and finding office space for staff and users. We approach these challenges with an eye for improvement from the “way we’ve always done it” to better ways of doing things. Being a small division, we need to be nimble and versatile. Cross-training and succession planning will be key to our success.

    It’s an exciting time for neutrino research at Fermilab. All of us at the Neutrino Division look forward to our role in building the laboratory’s future.

    To learn more about the new Neutrino Division and watch us evolve, please visit our website.

    See the full article here.

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  • richardmitnick 6:31 pm on November 10, 2014 Permalink | Reply
    Tags: , Particle Physics   

    From livescience: “Why a Physics Revolution Might Be on Its Way” 

    Livescience

    November 09, 2014
    Kelly Dickerson

    The field of physics may be turned on its head soon, said renowned physicist Nima Arkani-Hamed during a live lecture from the Perimeter Institute for Theoretical Physics in Waterloo, Canada.

    phy
    Credit: agsandrew | Shutterstock.com

    For one, he said, the tried and true physics of relativity and quantum mechanics don’t get along well. The problem is that in some sense, the principles behind these theories seem to be impossible when physicists dig a little deeper into them, Arkani-Hamed said. Scientists run into a lot of problems when they try to apply these theories to the entirety of space and time.

    The two ideas are also incredibly constraining, and they make it challenging for physicists to think outside the box and develop new ideas and theories, Arkani-Hamed said.

    “It’s almost impossible to monkey around with the rules and not be wrong immediately,” Arkani-Hamed said.

    Physicists have known about this disparity for a while, but progress on fundamental questions in physics takes a long time. Scientists proposed the existence of the Higgs boson particle, for example, decades before it was actually discovered.

    An unexplained macroscopic universe

    One problem is that conventional physics doesn’t really account for why the universe is so large, Arkani-Hamed said.

    Albert Einstein’s theory of relativity showed that a huge amount of energy exists in the vacuum of space, and it should curve space and time. In fact, there should be so much curvature that the universe is a tiny, crumpled ball.

    “That should make the universe horrendously different than what it is,” Arkani-Hamed said.

    But quantum mechanics also poses a problem. The theory is good at describing the very small realm of particle physics, but it breaks down when physicists try to apply it to the universe as a whole.

    “Everything that quantum mechanics is, is violated by our universe because we’re accelerating (referring to the idea that the universe is expanding) – we don’t know what the rules are,” Arkani-Hamed said. “When you try to apply quantum mechanics to the entire universe, quantum mechanics cries ‘uncle.’”

    Physics frontiers

    One possible way to solve the problem is with an entirely new theory beyond the Standard Model, the reigning theory of particle physics, the physicist said.

    sm
    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth

    One idea is called string theory, which proposes that particles aren’t actually fundamentally particles. Instead, the particles and all the matter in the universe they make up are composed of tiny, vibrating strings. The equations that support string theory appear to work, but that doesn’t mean there are no other viable formulas or explanations, Arkani-Hamed said.

    Supersymmetry is another possible “new physics” explanation. Under this idea, all subatomic particles have a “superpartner” particle that physicists have yet to discover. Supersymmetry would also open up extra directions that the particles can move in. The discovery of supersymmetry would bolster the Standard Model of physics, scientists have said.
    Supersymmetry standard model
    Standard Model of Supersymmetry

    “It’s the last thing nature can do to make itself compatible with the general principles of physics that already exist,” Arkani-Hamed said.

    When the world’s largest atom smasher, the Large Hadron Collider (LHC), is up and running again next year, physicists will be looking for the extra particles that supersymmetry suggests should exist.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    Either way, after a year or two of running the LHC, the question of whether supersymmetry exists should be answered, Arkani-Hamed said.

    The experiments over the next few years will likely tell physicists if they need to fine-tune existing theories or if the field of physics is due for a much deeper and more dramatic paradigm shift.

    The questions on the table now are the underpinnings of space and time, and the origin and fate of the universe, Arkani-Hamed said.

    “Today we finally have the theoretical framework in place to ask these kinds of big questions,” Arkani-Hamed said. “The next step will likely be a revolution.”

    See the full article here.

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  • richardmitnick 3:09 pm on November 8, 2014 Permalink | Reply
    Tags: , , , , Particle Physics, , , The Conversation   

    From The Conversation: “Cheaper, more compact particle accelerators are a step closer” 

    The Conversation
    The Conversation

    Scientists working on an experiment at the SLAC National Accelerator Laboratory in the US have taken a step forward in developing a technology which could significantly reduce the size of particle accelerators. The technology is able to accelerate particles more rapidly than conventional accelerators at a much smaller size.

    two
    Before the big bang. SLAC National Accelerator Laboratory

    One of the most impressive aspects of particle accelerators used for research such as the Large Hadron Collider (LHC) at CERN is its physical size.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    Yet, even with a circumference of 27km, the LHC would be smaller than most of the next generation of proposed colliders. For example the International Linear Collider (ILC), a possible future collider of electrons and positrons (anti-electrons) could be 31km long, and there is even a proposal for a circular accelerator with an 80km circumference that could be built at CERN as part of the Future Circular Colliders (FCC) project.

    ILC schematic
    ILC schematic

    future
    fut2
    With the discovery of the Higgs boson at the LHC in 2012, coupled with the absence of other phenomena, the particle physics panorama has become, surprisingly perhaps, very open. While the Standard Model could appear as a complete theory, several undeniable observations tell us that there is more to the story. The nature of dark matter, the origin of the baryon asymmetry in the universe, the mysteries lying behind the very small neutrino masses are telling us to keep looking for answers. Are the required new phenomena to be found at higher energies, or have they escaped detection because of very small couplings? The FCCs will address these fundamental open issues of particle physics.

    The size of all of these machines is determined by our ability to build structures that can transfer energy to particles allowing us to accelerate them to greater speeds. The higher the speed, the greater the energy when these particle beams collide, giving scientists a better chance of answering fundamental questions about the universe. This is because higher energy collisions can create conditions that are similar to those existing when the universe was born.

    Most current accelerators use a structure called an “rf cavity”, a carefully designed “box” through which the particle beam passes. The cavity transfers electromagnetic energy into the kinetic energy of particles, accelerating them. However, there is a limit to the amount of energy that an rf cavity can transfer to particles. This is because, despite operating in a vacuum, there is a risk that increasing electromagnetic fields can lead to lightning-like discharges of energy.

    However, even routine experiments in places like the LHC require more energy than a single rf cavity can provide. That is why the current solution is to use very many cavities arranged in a straight line, if it is a linear machine such as the SLAC, or using the same cavity very many times if it is in a circular machine, such as the LHC.

    Either solution presents challenges and requires a large machine to fit in the many parts needed. This raises the costs. Any technology which can increase the acceleration with smaller parts and without the need for more machinery will make future accelerators more compact.

    This matters because particle accelerators are not just for particle physicists. They are increasingly used in medicine, industry and security. For example, accelerators provide X-rays and particle beams for cancer therapy, for the fabrication of minuscule devices and for scanning the contents of everything from suitcases to freight containers.

    The new technology which could promise more compact particle accelerators has just been published in a study in Nature. The study suggests that, if bunches of electrons are passed through a short column of lithium vapour “plasma” in rapid succession, the electric field of the plasma is able to translate enough energy to accelerate particles hundreds of times quicker than the LHC. It is able to achieve all this while only being 30cm in length.

    Plasma is a state of matter where atoms are broken down into positively charged ions and negatively charged electrons. Most of the matter in the sun exists as plasma, but we can create that state on Earth using high energy lasers.

    The electric field between particles in a plasma can be extremely high. In this experiment, as the bunch of electrons passes through the plasma it causes the electrons of the plasma to move, leaving behind it a region of oscillating electrons. It is this oscillation which generate the “wakefield” which can then be used to accelerate a second set of trailing electrons following very close behind the first bunch.

    Although previous experiments have shown even greater gains in energy, what makes this experiment interesting is the number of electrons accelerated and how evenly each of them acquires energy. Being able to accelerate large numbers of particles to the same energy simultaneously is a prerequisite for any future practical use of this technology called “plasma wakefield acceleration”.

    Other groups around the world including the AWAKE collaboration at CERN and the ALPHA-X collaboration based at the University of Strathclyde are pursuing different approaches to plasma wakefield acceleration using proton beams or lasers to generate the wakefield. Meanwhile there are already tentative designs being proposed for future accelerators that could make use of this technology, if accelerating large numbers of particles simultaneously can be made reliable.

    See the full article here.

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  • richardmitnick 1:24 pm on November 8, 2014 Permalink | Reply
    Tags: , , , , , Particle Physics   

    From Daily Galaxy: “Discovery of “Higgs Boson” Points to an Undiscovered Force of Nature” 

    Daily Galaxy
    The Daily Galaxy

    November 08, 2014
    via University of Southern Denmark

    gal.

    Last year CERN [actually announced July 4.2012, editors] announced the finding of a new elementary particle, the Higgs particle. But maybe it wasn’t the Higgs particle, maybe it just looks like it. And maybe it is not alone. Many calculations indicate that the particle discovered last year in the CERN particle accelerator was indeed the famous Higgs particle. Physicists agree that the CERN experiments did find a new particle that had never been seen before, but according to an international research team, there is no conclusive evidence that the particle was indeed the Higgs particle.

    The research team has scrutinized the existing scientific data from CERN about the newfound particle and published their analysis in the journal Physical Review D. A member of this team is Mads Toudal Frandsen, associate professor at the Center for Cosmology and Particle Physics Phenomenology, Department of Physics, Chemistry and Pharmacy at the University of Southern Denmark.

    “The CERN data is generally taken as evidence that the particle is the Higgs particle. It is true that the Higgs particle can explain the data but there can be other explanations, we would also get this data from other particles”, Mads Toudal Frandsen explains.

    The researchers’ analysis does not debunk the possibility that CERN has discovered the Higgs particle. That is still possible – but it is equally possible that it is a different kind of particle. “The current data is not precise enough to determine exactly what the particle is. It could be a number of other known particles”, says Mads Toudal Frandsen.

    But if it wasn’t the Higgs particle, that was found in CERN’s particle accelerator, then what was it? “We believe that it may be a so-called techni-higgs particle. This particle is in some ways similar to the Higgs particle – hence half of the name”, says Mads Toudal Frandsen. Although the techni-higgs particle and Higgs particle can easily be confused in experiments, they are two very different particles belonging to two very different theories of how the universe was created.

    The Higgs particle is the missing piece in the theory called the Standard Model.
    sm
    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    This theory describes three of the four forces of nature. But it does not explain what dark matter is – the substance that makes up most of the universe. A techni-higgs particle, if it exists, is a completely different thing: “A techni-higgs particle is not an elementary particle. Instead, it consists of so-called techni-quarks, which we believe are elementary. Techni-quarks may bind together in various ways to form for instance techni-higgs particles, while other combinations may form dark matter. We therefore expect to find several different particles at the LHC, all built by techni-quarks”, says Mads Toudal Frandsen.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    If techni-quarks exist, there must be a force to bind them together so that they can form particles. None of the four known forces of nature (gravity, the electromagnetic force, the weak nuclear force and the strong nuclear force) are any good at binding techni-quarks together. There must therefore be a yet undiscovered force of nature. This force is called the the technicolor force.

    What was found last year in CERN’s accelerator could thus be either the Higgs particle of the Standard Model or a light techni-higgs particle, composed of two techni-quarks. Mads Toudal Frandsen believes that more data from CERN will probably be able to determine if it was a Higgs or a techni-higgs particle. If CERN gets an even more powerful accelerator, it will in principle be able to observe techni-quarks directly.

    The rest of the team behind the scientific paper is: Alexander Belyaev and Matthew S. Brown from the University of Southampton, UK and Roshan Foadi from the University of Helsinki, Finland.

    Ref: Technicolor Higgs boson in the light of LHC data. Phys. Rev. D 90, 035012th Alexander Belyaev, Matthew S. Brown, Roshan Foadi, and Mads T. Frandsen.

    Image at top of the page: The Black Eye galaxy is seen in this Hubble Space Telescope image released in 2004. Galaxies behave as if they contain much more mass than is visible to astronomers. NASA and the Hubble Heritage Team (AURA/STScI)

    See the full article here.

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