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  • richardmitnick 3:06 pm on January 6, 2018 Permalink | Reply
    Tags: , , Matter/Antimatter, , Neutrinos Suggest Solution to Mystery of Universe’s Existence, , , , T2K Experiment/Super-Kamiokande Collaboration   

    From Quanta: “Neutrinos Suggest Solution to Mystery of Universe’s Existence” 

    Quanta Magazine
    Quanta Magazine

    December 12, 2017
    Katia Moskvitch

    A neutrino passing through the Super-Kamiokande experiment creates a telltale light pattern on the detector walls. T2K Experiment/Super-Kamiokande Collaboration, Institute for Cosmic Ray Research, University of Tokyo

    T2K Experiment, Tokai to Kamioka, Japan

    T2K Experiment, Tokai to Kamioka, Japan

    From above, you might mistake the hole in the ground for a gigantic elevator shaft. Instead, it leads to an experiment that might reveal why matter didn’t disappear in a puff of radiation shortly after the Big Bang.

    I’m at the Japan Proton Accelerator Research Complex, or J-PARC — a remote and well-guarded government facility in Tokai, about an hour’s train ride north of Tokyo.

    J-PARC Facility Japan Proton Accelerator Research Complex , located in Tokai village, Ibaraki prefecture, on the east coast of Japan

    The experiment here, called T2K (for Tokai-to-Kamioka) produces a beam of the subatomic particles called neutrinos. The beam travels through 295 kilometers of rock to the Super-Kamiokande (Super-K) detector, a gigantic pit buried 1 kilometer underground and filled with 50,000 tons (about 13 million gallons) of ultrapure water. During the journey, some of the neutrinos will morph from one “flavor” into another.

    In this ongoing experiment, the first results of which were reported last year, scientists at T2K are studying the way these neutrinos flip in an effort to explain the predominance of matter over antimatter in the universe. During my visit, physicists explained to me that an additional year’s worth of data was in, and that the results are encouraging.

    According to the Standard Model of particle physics, every particle has a mirror-image particle that carries the opposite electrical charge — an antimatter particle.

    Standard Model of Particle Physics from Symmetry Magazine

    When matter and antimatter particles collide, they annihilate in a flash of radiation. Yet scientists believe that the Big Bang should have produced equal amounts of matter and antimatter, which would imply that everything should have vanished fairly quickly. But it didn’t. A very small fraction of the original matter survived and went on to form the known universe.

    Researchers don’t know why. “There must be some particle reactions that happen differently for matter and antimatter,” said Morgan Wascko, a physicist at Imperial College London. Antimatter might decay in a way that differs from how matter decays, for example. If so, it would violate an idea called charge-parity (CP) symmetry, which states that the laws of physics shouldn’t change if matter particles swap places with their antiparticles (charge) while viewed in a mirror (parity). The symmetry holds for most particles, though not all. (The subatomic particles known as quarks violate CP symmetry, but the deviations are so small that they can’t explain why matter so dramatically outnumbers antimatter in the universe.)

    Last year, the T2K collaboration announced the first evidence that neutrinos might break CP symmetry, thus potentially explaining why the universe is filled with matter. “If there is CP violation in the neutrino sector, then this could easily account for the matter-antimatter difference,” said Adrian Bevan, a particle physicist at Queen Mary University of London.

    Researchers check for CP violations by studying differences between the behavior of matter and antimatter. In the case of neutrinos, the T2K scientists explore how neutrinos and antineutrinos oscillate, or change, as the particles make their way to the Super-K detector. In 2016, 32 muon neutrinos changed to electron neutrinos on their way to Super-K. When the researchers sent muon antineutrinos, only four became electron antineutrinos.

    That result got the community excited — although most physicists were quick to point out that with such a small sample size, there was still a 10 percent chance that the difference was merely a random fluctuation. (By comparison, the 2012 Higgs boson discovery had less than a 1-in-1 million probability that the signal was due to chance.)

    This year, researchers collected nearly twice the amount of neutrino data as last year. Super-K captured 89 electron neutrinos, significantly more than the 67 it should have found if there was no CP violation. And the experiment spotted only seven electron antineutrinos, two fewer than expected.

    Lucy Reading-Ikkanda for Quanta Magazine

    Researchers aren’t claiming a discovery just yet. Because there are still so few data points, “there’s still a 1-in-20 chance it’s just a statistical fluke and there isn’t even any violation of CP symmetry,” said Phillip Litchfield, a physicist at Imperial College London. For the results to become truly significant, he added, the experiment needs to get down to about a 3-in-1000 chance, which researchers hope to reach by the mid-2020s.

    But the improvement on last year’s data, while modest, is “in a very interesting direction,” said Tom Browder, a physicist at the University of Hawaii. The hints of new physics haven’t yet gone away, as we might expect them to do if the initial results were due to chance. Results are also trickling in from another experiment, the 810-kilometer-long NOvA at the Fermi National Accelerator Laboratory outside Chicago.

    FNAL/NOvA experiment map

    FNAL NOvA Near Detector

    Last year it released its first set of neutrino data, with antineutrino results expected next summer. And although these first CP-violation results will also not be statistically significant, if the NOvA and T2K experiments agree, “the consistency of all these early hints” will be intriguing, said Mark Messier, a physicist at Indiana University.

    A planned upgrade of the Super-K detector might give the researchers a boost. Next summer, the detector will be drained for the first time in over a decade, then filled again with ultrapure water. This water will be mixed with gadolinium sulfate, a type of salt that should make the instrument much more sensitive to electron antineutrinos. “The gadolinium doping will make the electron antineutrino interaction easily detectable,” said Browder. That is, the salt will help the researchers to separate antineutrino interactions from neutrino interactions, improving their ability to search for CP violations.

    “Right now, we are probably willing to bet that CP is violated in the neutrino sector, but we won’t be shocked if it is not,” said André de Gouvêa, a physicist at Northwestern University. Wascko is a bit more optimistic. “The 2017 T2K result has not yet clarified our understanding of CP violation, but it shows great promise for our ability to measure it precisely in the future,” he said. “And perhaps the future is not as far away as we might have thought last year.”

    See the full article here .

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    Formerly known as Simons Science News, Quanta Magazine 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 8:20 am on August 31, 2015 Permalink | Reply
    Tags: , , Matter/Antimatter   

    From COSMOS: “Captured: antimatter from the centre of the Earth” 

    Cosmos Magazine bloc


    31 Aug 2015
    Belinda Smith

    Physicists are probing the secrets of the planet’s inner workings by capturing elusive antimatter particles. Belinda Smith explains.

    The middle layer of our planet is a mystery. It makes up 84% of the Earth’s volume, but we’ve little idea what’s in there or how much heat it produces, or how it affects the plate tectonics our planet depends on. That’s about to change thanks to a technique that measures ghostly anti-particles slipping out of their radioactive graves in the mantle below.

    An international team at Italy’s Gran Sasso National Laboratory published the calculations in Physical Review D in August. Their sums suggest that more than half our planet’s internal heat comes from radioactive decay within the mantle.

    The findings have been welcomed by researchers eager to plumb the mystery of the mantle. “We know more about the heavens than what’s happening below,” says Zheng-Xiang Li, geoscientist at Curtin University in Perth, Australia.

    The crusty outer layer of Earth is well understood, but the mantle below is a mystery. We do know it is 2,900 kilometres thick. But efforts to drill through the crust – which is 40 kilometres thick, on average – to reach the mantle have failed. The furthest we got was 12 kilometres when Russian engineers drilled the Kola Superdeep Borehole, the world’s deepest hole. They drilled for 20 years but as the drills neared the mantle, the intense heat wrecked the machinery. Funding ran out in 2005 and the site has been abandoned since 2008.

    So geologists use indirect techniques to make their investigations. The mantle (and crust) contains radioactive uranium and thorium. As they decay into lighter elements, they emit ghostly geoneutrinos that pass through rock as if it wasn’t there.

    You might already be familiar with a closely related particle, neutrinos. These are uncharged, inert, ghostly particles produced by fusion reactions in the Sun, distant supernovae and other cosmic events. Because they rarely interact with other particles, they’re exceptionally hard to detect.

    Geoneutrinos are their antimatter equivalent – and are equally elusive. (Antimatter is composed of antiparticles. They have the same mass as particles of ordinary matter but an opposite charge.)

    When a neutron inside a thorium or uranium atom decays, a proton, an electron and a geoneutrino are emitted. While protons and electrons are everywhere, the rare geoneutrino is the perfect marker for measuring remote radioactivity.

    To pick up geoneutrinos’ infrequent interactions, detectors must be big and well shielded from stray, more interactive particles. Cue the Borexino instrument at the Gran Sasso National Laboratory in Italy. “It’s the only tool we have to study the interior of the Earth,” says Aldo Ianni, a physicist at Canfranc Laboratory in Spain as well as a member of the Borexino team.

    A scientist checks the photodetectors inside the Borexino neutrino detector at Gran Sasso Laboratories.Credit: VOLKER STEGER/gettyimages

    It consists of an 18-metre steel box buried 800 metres underground. When a geoneutrino slips past the layers of steel and pure water designed to keep other particles out, it eventually reaches a central tank filled with a hydrogen-rich fluid.

    In this environment, if a geoneutrino crashes into a proton, they produce a positron (an electron with a positive charge) and a neutron. The positron immediately annihilates and as it does, it puffs out a burst of light picked up by super-sensitive photodetectors placed around the tank.

    The neutron, on the other hand, is captured by a hydrogen atom, which becomes the slightly heavier deuterium. As it slots the extra neutron in its nucleus it shoots out a gamma ray – which is also spotted by photodetectors.

    The time delay between the annihilating positron’s flash and the gamma ray is a reliable 250 milliseconds, “a very strong signature” that a geoneutrino has been captured, Ianni says.

    Ianni’s team picked up 77 flashes with the geoneutrino signature from December 2007 to March 2015. Some 53 were traced to nearby nuclear reactors (a known geoneutrino source). That left 24. Crust radioactivity accounted for 12 flashes leaving 12 unaccounted for. The researchers believe there’s a 98% chance at least some of these came from the mantle.

    Based on the energies of the mantle geoneutrinos they spotted, the team could calculate that 50-70% of the heat the Earth emits into space is generated by radioactivity in the mantle – up to double previous estimates.

    Knowing how much heat the mantle produces, geophysicists may one day be able to map how heat is transferred from Earth’s hot liquid core via the mantle to the crust. And because motion in the mantle tugs on the overlying crust, mapping this flow could give new insights into the processes driving plate tectonics and earthquakes, volcanic eruptions and lava flows, says Li.

    The Borexino researchers plan to run the detector for another three to five years, until the light-sensitive photodetectors age.

    There’s more data to come though, both from Borexino and the KamLAND antineutrino detector, buried in an old mine shaft under the Japanese Alps. And a new detector – the SNO+ underground experiment in Ontario, Canada – is under construction. The more the better, Ianni says, to “combine data and disentangle the models, and build a bridge between particle physics and geophysics.”

    KamLAND Detector


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  • richardmitnick 2:41 pm on August 13, 2015 Permalink | Reply
    Tags: , , Matter/Antimatter   

    From CERN: “The BASE experiment at CERN compares protons and antiprotons with high precision” 

    CERN New Masthead

    12 Aug 2015
    No Writer Credit

    In a paper published today in Nature, the Baryon Antibaryon Symmetry Experiment (BASE1) at CERN’s Antiproton Decelerator (AD), reports the most precise comparison of the charge-to-mass ratio of the proton to that of its antimatter equivalent, the antiproton. The charge-to-mass ratio — an important property of particles — can be measured by observing the oscillation of a particle in a magnetic field. The new result shows no difference between the proton and the antiproton, with a four-fold improvement in the energy resolution compared with previous measurements.

    A cut-away schematic of the Penning trap system used by BASE. The experiment receives antiprotons from CERN’s AD; negative hydrogen ions are formed during injection into the apparatus. The set-up works with only a pair of particles at a time, while a cloud of a few hundred others are held in the reservoir trap, for future use. Here, an antiproton is in the measurement trap, while the negative hydyrogen ion is in held by the downstream park electrode. When the antiproton has been measured, it is moved to the upstream park electrode and the hydrogen ion is brought in to the measurement trap. This is repeated thousands of times, enabling a high-precision comparison of the charge-to-mass ratios of the two particles. (Image: CERN)

    To perform the experiment, the BASE collaboration used a Penning-trap system comparable to that developed by the TRAP collaboration in the late 1990s at CERN. However, the method used is faster than in previous experiments. This has allowed BASE to carry out about 13 000 measurements over a 35-day campaign, in which they compare a single antiproton to a negatively-charged hydrogen ion (H-). Consisting of a hydrogen atom with a single proton in its nucleus, together with an additional electron, the H- acts as a proxy for the proton.

    “We found that the charge-to-mass ratio is identical to within 69 parts per thousand billion, supporting a fundamental symmetry between matter and antimatter,” said BASE spokesperson Stefan Ulmer.

    “Research performed with antimatter particles has made amazing progress in the past few years,” said CERN Director General Rolf Heuer. “I’m really impressed by the level of precision reached by BASE. It’s very promising for the whole field.”

    The Standard Model of particle physics – the theory that best describes particles and their fundamental interactions – is known to be incomplete, inspiring various searches for “new physics” that goes beyond the model.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    These include tests that compare the basic characteristics of matter particles with those of their antimatter counterparts. While matter and antimatter particles can differ, for example, in the way they decay (a difference often referred to as violation of CP symmetry), other fundamental properties, such as the absolute value of their electric charges and masses, are predicted to be exactly equal. Any difference – however small — between the charge-to-mass ratio of protons and antiprotons would break a fundamental law known as CPT symmetry. This symmetry reflects well-established properties of space and time and of quantum mechanics, so such a difference would constitute a dramatic challenge not only to the Standard Model, but also to the basic theoretical framework of particle physics.

    The BASE experiment receives antiprotons from the AD, a unique facility in the world for antimatter research. The H- ions are formed by the antiproton injection. The set-up holds a single antiproton–H- pair at a time in a magnetic Penning trap, decelerating the particles to ultra-low energies. The experiment then measures the cyclotron frequency of the antiproton and the H- ion — a measurement that allows the team to determine the charge-to-mass ratio — and compares the results.

    BASE was approved in 2013. Using a set-up of multiple Penning traps, its ultimate goal is to measure with very high precision the antiproton’s magnetic moment, another important property of particles. The collaboration has already performed the most precise measurement of the magnetic moment of the proton and will apply the technique next to the antiproton.

    Picture of the Penning trap system used by the BASE experiment (Image: CERN)


    1. The BASE collaboration consists of researchers from RIKEN, CERN, Max Planck Institute for Nuclear Physics, University of Tokyo, Johannes Gutenberg University of Mainz, GSI Helmholtz Centre for Heavy Ion Research, and Helmholtz Institute Mainz.

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  • richardmitnick 5:06 pm on August 12, 2015 Permalink | Reply
    Tags: , , Matter/Antimatter   

    From livescience: “Mystery Deepens: Matter and Antimatter Are Mirror Images” 


    August 12, 2015
    Charles Q. Choi

    A newly reported experiment involving matter and antimatter was carried out in CERN’s Antiproton Decelerator.

    Matter and antimatter appear to be perfect mirror images of each other as far as anyone can see, scientists have discovered with unprecedented precision, foiling hope of solving the mystery as to why there is far more matter than antimatter in the universe.

    Everyday matter is made up of protons, neutrons or electrons. These particles have counterparts known as antiparticles — antiprotons, antineutrons and positrons, respectively — that have the same mass but the opposite electric charge. (Although neutrons and antineutrons are both neutrally charged, they are each made of particles known as quarks that possess fractional electrical charges, and the charges of these quarks are equal and opposite to one another in neutrons and antineutrons.)

    The known universe is composed of everyday matter. The profound mystery is, why the universe is not made up of equal parts antimatter, since the Big Bang that is thought to have created the universe 13.7 billion years ago produced equal amounts of both. And if matter and antimatter appear to be mirror images of each other in every respect save their electrical charge, there might not be much any of either type of matter left — matter and antimatter annihilate when they encounter each other.

    Checking charge parity

    Theoretical physicists suspect that the extraordinary contrast between the amounts of matter and antimatter in the universe, technically known as baryon asymmetry, may be due to some difference between the properties of matter and antimatter, formally known as a charge-parity, or CP symmetry violation. However, all the known effects that lead to violations of CP symmetry fail to explain the vast preponderance of matter over antimatter.

    Potential explanations behind this mystery could lie in differences in the properties of matter and antimatter — for instance, perhaps antiprotons decay faster than protons. If any such difference is found, however slight, “this will of course lead to dramatic consequences for our contemporary understanding of the fundamental laws of physics,” study lead author Stefan Ulmer, a particle physicist at Japan’s Institute of Physical and Chemical Research (RIKEN), told Live Science.

    In the most stringent test yet of differences between protons and antiprotons, scientists investigated the ratio of electric charge to mass in about 6,500 pairs of these particles over a 35-day period. To keep antimatter and matter from coming into contact, the researchers trapped protons and antiprotons in magnetic fields. Then they measured how these particles moved in a cyclical manner in those fields, a characteristic known as their cyclotron frequency, which is proportional to both the charge-to-mass ratio of those particles and the strength of the magnetic field.

    (Technically, the researchers did not use simple protons in the experiments, but negative hydrogen ions, which each consist of a proton surrounded by two electrons. This was done to simplify the experiments — antiprotons and negative hydrogen ions are both negatively charged, and so respond the same way to magnetic fields. The scientists could easily account for the effects these electrons had during the experiments.)

    Perfect mirror images

    The scientists found the charge-to-mass ratio of protons and antiprotons “is identical to within just 69 parts per trillion,” Ulmer said in a statement. This measurement is four times better than previous measurements of this ratio.

    In addition, the researchers also discovered that the charge-to-mass ratios they measured do not vary by more than 720 parts per trillion per day, as Earth rotates on its axis and travels around the sun. This suggests that protons and antiprotons behave the same way over time as they zip through space at the same velocity, meaning they do not violate what is known as charge-parity-time, or CPT symmetry.

    CPT symmetry is a key component of the Standard Model of particle physics, the best description to date of how the elementary particles making up the universe behave. No known violations of CPT symmetry exist. “Any detected CPT violation will have huge impact on our understanding of nature,” Ulmer said.

    Furthermore, these charge-to-mass ratios did not differ by more than 870 parts per billion in Earth’s gravitational field. This means the weak equivalence principle, which holds that all matter falls at the same rate in the same gravitational field, also holds at this level of accuracy. The weak equivalence principle is a keystone of Einstein’s theory of general relativity, which among other things is the best explanation so far of how gravity works. No known violations of the weak equivalence principle exist, and any detected violations of it could lead to a revolution in science’s understanding of gravity and space-time, and how both relate to matter and energy.

    Using more stable magnetic fields and other approaches, the scientists plan to achieve measurements that are at least 10 times more precise than what they found so far, Ulmer said.

    The scientists detailed their latest findings online Aug. 13 in the journal Nature.

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  • richardmitnick 3:03 pm on February 26, 2015 Permalink | Reply
    Tags: , Matter/Antimatter,   

    From UCLA: “UCLA physicists offer a solution to the puzzle of the origin of matter in the universe” 

    UCLA bloc


    February 24, 2015
    Stuart Wolpert

    Alexander Kusenko

    Most of the laws of nature treat particles and antiparticles equally, but stars and planets are made of particles, or matter, and not antiparticles, or antimatter. That asymmetry, which favors matter to a very small degree, has puzzled scientists for many years.

    New research by UCLA physicists, published in the journal Physical Review Letters, offers a possible solution to the mystery of the origin of matter in the universe.

    Alexander Kusenko, a professor of physics and astronomy in the UCLA College, and colleagues propose that the matter-antimatter asymmetry could be related to the Higgs boson particle, which was the subject of prominent news coverage when it was discovered at Switzerland’s Large Hadron Collider in 2012.

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

    Specifically, the UCLA researchers write, the asymmetry may have been produced as a result of the motion of the Higgs field, which is associated with the Higgs boson, and which could have made the masses of particles and antiparticles in the universe temporarily unequal, allowing for a small excess of matter particles over antiparticles.

    If a particle and an antiparticle meet, they disappear by emitting two photons or a pair of some other particles. In the “primordial soup” that existed after the Big Bang, there were almost equal amounts of particles of antiparticles, except for a tiny asymmetry: one particle per 10 billion. As the universe cooled, the particles and antiparticles annihilated each other in equal numbers, and only a tiny number of particles remained; this tiny amount is all the stars and planets, and gas in today’s universe, said Kusenko, who is also a senior scientist with the Kavli Institute for the Physics and Mathematics of the Universe.

    The research also is highlighted by Physical Review Letters in a commentary in the current issue.

    The 2012 discovery of the Higgs boson particle was hailed as one of the great scientific accomplishments of recent decades. The Higgs boson was first postulated some 50 years ago as a crucial element of the modern theory of the forces of nature, and is, physicists say, what gives everything in the universe mass. Physicists at the LHC measured the particle’s mass and found its value to be peculiar; it is consistent with the possibility that the Higgs field in the first moments of the Big Bang was much larger than its “equilibrium value” observed today.

    The Higgs field “had to descend to the equilibrium, in a process of ‘Higgs relaxation,’” said Kusenko, the lead author of the UCLA research.

    Two of Kusenko’s graduate students, Louis Yang of UCLA and Lauren Pearce of the University of Minnesota, Minneapolis, were co-authors of the study. The research was supported by the U.S. Department of Energy (DE-SC0009937), the World Premier International Research Center Initiative in Japan and the National Science Foundation (PHYS-1066293).

    See the full article here.

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    UC LA Campus

    For nearly 100 years, UCLA has been a pioneer, persevering through impossibility, turning the futile into the attainable.

    We doubt the critics, reject the status quo and see opportunity in dissatisfaction. Our campus, faculty and students are driven by optimism. It is not naïve; it is essential. And it has fueled every accomplishment, allowing us to redefine what’s possible, time after time.

    This can-do perspective has brought us 12 Nobel Prizes, 12 Rhodes Scholarships, more NCAA titles than any university and more Olympic medals than most nations. Our faculty and alumni helped create the Internet and pioneered reverse osmosis. And more than 100 companies have been created based on technology developed at UCLA.

  • richardmitnick 5:05 pm on February 23, 2015 Permalink | Reply
    Tags: , Matter/Antimatter, ,   

    From Scientific American: “Higgs Boson Could Explain Matter’s Dominance over Antimatter” 

    Scientific American

    Scientific American

    February 20, 2015
    Clara Moskowitz

    Computer simulation of particle tracks from an LHC collision that produced a Higgs boson.

    The stars, the planets and you and I could just as easily be made of antimatter as matter, but we are not. Something happened early in the universe’s history to give matter the upper hand, leaving a world of things built from atoms and little trace of the antimatter that was once as plentiful but is rare today. A new theory published February 11 in Physical Review Letters suggests the recently discovered Higgs boson particle may be responsible—more particularly, the Higgs field that is associated with the particle.

    The Higgs field is thought to pervade all of space and imbue particles that pass through it with mass, akin to the way liquid dye gives Easter eggs color when they are dunked in. If the Higgs field started off with a very high value in the early universe and decreased to its current lower value over time, it might have briefly differentiated the masses of particles from their antiparticles along the way—an anomaly, because antimatter today is characterized by having the same mass but opposite charge as its matter counterpart. This difference in mass, in turn, could have made matter particles more likely to form than antimatter in the cosmos’ early days, producing the excess of matter we see today. “It is a nice idea that deserves further study,” says physicist Kari Enqvist of the University of Helsinki, who was not involved in the new study but who has also researched the possibility that the Higgs field lowered over time. “There is a very high probability for the Higgs field to have a high initial value after inflation.”

    The inflation of the universe

    Inflation is a theorized early epoch of the universe in which spacetime rapidly ballooned. “Inflation has a very peculiar property; it allows fields to jump around,” says study leader Alexander Kusenko of the University of California, Los Angeles. During inflation, which radically altered the universe in a span much less than a second, the Higgs field might have hopped from one value to another due to quantum fluctuations and could have gotten stuck at a very high value when inflation ended. From there it would have settled down into its lower “equilibrium” value, but while it was changing its constantly varying value could have given matter particles different masses than their antimatter counterparts. Because lighter particles require less energy to form they arise more often. Thus, if matter was lighter, it could have quickly become more plentiful.

    The reason the Higgs field would have had such an easy time of jumping around during inflation is that the measured mass of the Higgs boson, the particle associated with the field, is relatively low. The boson appeared in 2012 inside the Large Hadron Collider (LHC) in Switzerland, revealing its mass to be about 126 GeV (giga-electron volts), or roughly 118 times the mass of the proton.

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

    That is somewhat lighter than it could have been, according to various theories. Think of the Higgs field as a valley between two cliffs. The value of the field is akin to the elevation of the valley, and the mass of the boson determines the slope of the cliff walls. “If you have a very curved valley then you probably have very steep sides,” Kusenko says. “That’s what we discovered. This value tells us that the walls are not very steep—that means the Higgs field could jump around and go very far” to other valleys at higher elevations. Enqvist agrees that the Higgs could very well have started off much higher than it is today. Whether or not this caused the matter to split from antimatter is “somewhat more speculative,” he says.

    A new particle

    Such splitting would depend on the presence of a theorized particle that has gone undetected so far: a so-called heavy Majorana neutrino. Neutrinos are fundamental particles that come in three flavors (electron, muon and tau). A fourth neutrino might also exist, however, that is expected to be much heavier than the others and thus more difficult to detect (because the heavier a particle is, the more energy a collider must produce to create it). This particle would have the strange virtue of being its own antimatter partner. Instead of a matter and antimatter version of the particle, the matter and antimatter Majorana neutrinos would be one and the same.

    This two-faced quality would have made neutrinos into a bridge that allowed matter particles to cross over into antimatter particles and vice versa in the early universe. Quantum laws allow particles to transform into other particles for brief moments of time. Normally they are forbidden from converting between matter and antimatter. But if an antimatter particle, say, an antielectron neutrino turned into a Majorana neutrino, it would cease to know whether it was matter or antimatter and could then just as easily convert to a regular electron neutrino as turn back into its original antielectron neutrino self. And if the neutrino happened to be lighter than the antineutrino back then, because of the varying Higgs field, then the neutrino would have been a more likely outcome—potentially giving matter a leg up on antimatter.

    “If true, this would solve a big mystery in particle physics,” says physicist Don Lincoln of the Fermi National Accelerator Laboratory in Illinois, who was not involved in the study. Yet the Majorana neutrino “is entirely speculative and has eluded discovery, even though the LHC experiments have a vigorous research program looking for it. Researchers will certainly keep this idea in mind as they dig through the new data the LHC will begin generating in the early summer this year.”

    Kusenko and his colleagues also have another hope for finding additional support for their theory. The Higgs field process they envision could have created magnetic fields with particular properties that would still inhabit the universe today—and if so, they might be detectable. If found, the existence of such fields would provide evidence that the Higgs field really did decrease in value long ago. The scientists are trying to calculate just what the magnetic field properties would be and whether experiments have a plausible hope of seeing them, but the option raises the tantalizing hope that their theory could have testable consequences—and maybe a chance to solve the antimatter mystery after all.

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  • richardmitnick 10:05 am on October 31, 2013 Permalink | Reply
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    From Fermilab- “Frontier Science Result: DZero Muons, matter and mystery” 

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

    Thursday, Oct. 31, 2013
    Mark Williams

    Experiments at particle colliders are often described as “recreating the big bang”: making new particles out of energy, and then watching to see what happens. In almost all such experiments, we find that matter and antimatter are produced in equal amounts, and this is consistent with our current model. However, if the big bang followed the same rules, all the matter and antimatter would have mutually annihilated, with nothing left to form stars, planets and life. The very fact that we exist, and observe a matter-dominated universe, shows that our picture of the particle interactions is not complete.

    At the DZero experiment, scientists have spent a decade studying this matter-antimatter asymmetry using muons produced in their detector, and last week they released their final results. The measurement counts the number of observed muons (negatively charged) and antimuons (positively charged) to compare the amount of matter and antimatter resulting from the originally symmetric proton-antiproton collisions.

    As an analogy, this is much like weighing the matter and antimatter with a set of scales. The challenge is that the scales themselves introduce their own asymmetry into the measurement. Because the detector is built out of matter, it responds slightly differently to matter and antimatter particles as they are detected. These “detector effects” must be precisely determined before the measurement can be made. Luckily, the DZero detector has some clever attributes that make it uniquely suited for this kind of analysis.

    The new measurement uses the DZero detector like a set of scales, weighing the amount of matter and antimatter. However, the scales are themselves asymmetric, and the main challenge is to understand and quantify the effect of this behavior.

    Intriguingly, after correcting for the detector effects, the results indicate a statistically significant asymmetry in the number of same-charge muon pairs, with around one part in 400 more pairs of negative muons than positive muons. This is much larger than can be accounted for by current theories, suggesting the presence of additional as-yet unknown processes that favor the production of matter over antimatter. Now, assuming that this isn’t a very unlikely statistical fluctuation, the big question is: What could be causing this asymmetry, and could it be the same process that helped shape the early universe? Future precision measurements of specific asymmetries, as well as theoretical developments, are needed to help understand this puzzle.

    See the full article here.

    Fermilab Campus

    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 6:12 am on September 28, 2013 Permalink | Reply
    Tags: , , Matter/Antimatter   

    From Brookhaven Lab: “Supercomputers Help Solve a 50-Year Homework Assignment” 

    Brookhaven Lab

    Calculation related to question of why the universe is made of matter.

    September 26, 2013
    Karen McNulty Walsh

    Kids everywhere grumble about homework. But their complaints will hold no water with a group of theoretical physicists who’ve spent almost 50 years solving one homework problem—a calculation of one type of subatomic particle decay aimed at helping to answer the question of why the early universe ended up with an excess of matter.

    Without that excess, the matter and antimatter created in equal amounts in the Big Bang would have completely annihilated one another. Our universe would contain nothing but light—no homework, no schools…but also no people, or planets, or stars!

    According to the Big Bang model, the Universe expanded from an extremely dense and hot state and continues to expand today. A common analogy explains that space itself is expanding, carrying galaxies with it, like spots on an inflating balloon. The graphic scheme above is an artist’s concept illustrating the expansion of a portion of a flat universe.

    Physicists long ago figured out something must have happened to explain the imbalance—and our very existence.

    “Our results will serve as a tough test for our current understanding of particle physics.”
    — Brookhaven theoretical physicist Taku Izubuchi

    “The fact that we have a universe made of matter strongly suggests that there is some violation of symmetry,” said Taku Izubuchi, a theoretical physicist at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory.

    Members of Brookhaven Lab’s high-energy physics theory group who were involved in the kaon decay calculations Sitting, left to right: Christoph Lehner, Amarjit Soni, Taku Izubuchi, Christopher Kelly, Chulwoo Jung. Standing, left to right: Eigo Shintani, Hyung-Jin Kim, Ethan Neil, Taichi Kawanai, Tomomi Ishikawa

    The physicists call it charge conjugation-parity (CP) violation. Instead of everything in the universe behaving perfectly symmetrically, certain subatomic interactions happen differently if viewed in a mirror (violating parity) or when particles and their oppositely charged antiparticles swap each other (violating charge conjugation symmetry). Scientists at Brookhaven—James Cronin and Val Fitch—were the first to find evidence of such a symmetry “switch-up” in experiments conducted in 1964 at the Alternating Gradient Synchrotron, with additional evidence coming from experiments at CERN, the European Laboratory for Nuclear Research. Cronin and Fitch received the 1980 Nobel Prize in physics for this work.

    Theoretical physicists and kaon-decay calculators Norman Christ, Robert Mawhinney (both of Columbia University), and Taku Izubuchi (of Brookhaven), holding one rack of the QCDOC supercomputer at Brookhaven, which was used for many of the earlier kaon calculations. It was replaced by QCDCQ in 2012.

    What was observed was the decay of a subatomic particle known as a kaon into two other particles called pions. Kaons and pions (and many other particles as well) are composed of quarks. Understanding kaon decay in terms of its quark composition has posed a difficult problem for theoretical physicists.

    “That was the homework assignment handed to theoretical physicists, to develop a theory to explain this kaon decay process—a mathematical description we could use to calculate how frequently it happens and whether or how much it could account for the matter-antimatter imbalance in the universe. Our results will serve as a tough test for our current understanding of particle physics,” Izubuchi said.

    The mathematical equations of Quantum Chromodynamics, or QCD—the theory that describes how quarks and gluons interact—have a multitude of variables and possible values for those variables. So the scientists needed to wait for supercomputing capabilities to evolve before they could actually solve them. The physicists invented the complex algorithms and wrote nifty software packages that some of the world’s most powerful supercomputers used to describe the quarks’ behavior and solve the problem.

    The supercomputing resources used for this research included: QCDCQ, a pre-commercial version of the IBM Blue Gene supercomputers, located at the RIKEN/BNL Research Center—a center funded by the Japanese RIKEN laboratory in a cooperative agreement with Brookhaven Lab; a Blue Gene/Q supercomputer of the New York State Center for Computational Science, hosted by Brookhaven; half a rack of an additional Blue Gene/Q funded by DOE through the US based lattice QCD consortium, USQCD; a Blue Gene/Q machine at the Edinburgh Parallel Computing Centre; the large installation of BlueGene/P (Intrepid) and Blue Gene/Q (Mira) machines at Argonne National Laboratory funded by the DOE Office of Science; and PC cluster machines at Fermi National Accelerator Laboratory and at RIKEN.

    See the full article here.

    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 3:50 pm on August 16, 2013 Permalink | Reply
    Tags: , , Matter/Antimatter,   

    From Symmetry: "Antimatter experiment seeks help from the crowd" 

    After a successful trial run, a CERN antimatter experiment plans to use crowdsourcing to analyze its data.

    August 16, 2013
    Ashley WennersHerron and Kathryn Jepsen

    “Scientists investigating the effect of gravity on animatter recently conducted a different kind of experiment: They asked members of the public to help them analyze their data. Anyone with access to a computer and the Internet was welcome to take part in the trial run, which went off without a hitch. The scientists plan to do it again in the coming months.

    The AEgIS experiment at CERN examines beams of antimatter particles, recording the points at which they begin to deviate from their normal trajectories and the points at which they come into contact with matter and annihilate. Seeing how quickly—and in what direction—the particles fall will offer insight into just how the antimatter feels gravity’s pull.


    The experiment requires the scientists to match up pairs of dots to trace each particle’s path. They have a lot of dots to connect. ‘We have so much data that automation or many volunteers are the only options at this point,’ says CERN physicist Michael Doser, who leads the experiment. The scientists could try to create a program to do this job, Doser says, but people are just better than machines at this kind of pattern recognition. ‘So we brought the data to the people.’

    The scientists decided to release a small fraction of the data to the public as a test.

    The crowdsourcing software renders the particle tracks as a 3D image. Courtesy of: CERN

    Last month, a small group of students at CERN’s Summer Student Webfest designed a crowdsourcing program for AEgIS. Last week, the experiment put out the call for help. In the first hour, several hundred volunteers completed the task. ‘I expect a publication or two sometime in early 2014 on this analysis which directly benefits from help from the public,’ Doser says.

    Anyone interested in taking part in the next experiment in armchair physics can watch for the call on the AEgIS website. ”

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.

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  • richardmitnick 4:57 pm on April 30, 2013 Permalink | Reply
    Tags: , , , , , Matter/Antimatter   

    From Symmetry: “Matter, antimatter, we all fall down—right?” 

    April 30, 2013
    Ashley WennersHerron

    Scientists perform the first direct investigation into how antimatter interacts with gravity.

    What goes up must come down, the saying goes. But things might work a little differently with antimatter.
    A CERN-based experiment has taken the first step in investigating exactly how antimatter interacts with gravity.

    Photo: CERN

    Atimatter particles should mimic those of matter particles. If it turns out that there is a difference, it will be a sign of dramatically new physics.
    CERN ALPHA NewSo far, no one has been able to test directly how antimatter interacts with gravity—but the ALPHA experiment has begun to try.

    The ALPHA experiment’s main purpose is to trap and study antihydrogen atoms, the antimatter partners of hydrogen atoms. The antihydrogen atoms are held in place inside a tube by magnetic forces. Physicists on ALPHA have trapped more than 500 antiatoms since 2010. They keep them in their trap for up to about 16 minutes. When they turn off their magnets, the antiatoms fall out of the trap. A highly sensitive detector tracks the antiatoms and records where they first come in contact with matter and annihilate.”

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.

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