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  • richardmitnick 12:12 pm on October 30, 2014 Permalink | Reply
    Tags: , , CP Violation, , , ,   

    From FNAL- “Frontier Science Result: CDF A charming result” 


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

    Thursday, Oct. 30, 2014
    Diego Tonelli and Andy Beretvas

    Physicists gave funny names to the heavy quark cousins of those that make up ordinary matter: charm, strange, bottom, top. The Standard Model predicts that the laws governing the decays of strange, charm and bottom quarks differ if particles are replaced with antiparticles and observed in a mirror. This difference, CP violation in particle physics lingo, has been established for strange and bottom quarks. But for charm quarks the differences are so tiny that no one has observed them so far. Observing differences larger than predictions could provide much sought-after indications of new phenomena.

    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.

    A team of CDF scientists searched for these tiny differences by analyzing millions of decays of particles decaying into pairs of charged kaons and pions, sifting through roughly a thousand trillion proton-antiproton collisions from the full CDF Run II data set. They studied CP violation by looking at whether the difference between the numbers of charm and anticharm decays occurring in each chunk of decay time varies with decay time itself.

    The results have a tiny uncertainty (two parts per thousand) but do not show any evidence for CP violation, as shown in the upper figure. The small residual decay asymmetry, which is constant in decay time, is due to the asymmetric layout of the detector. The combined result of charm decays into a pair of kaons and a pair of pions is the CP asymmetry parameter AΓ , which is equal to -0.12 ± 0.12 percent. The results are consistent with the current best determinations. Combined with them, they will improve the exclusion constraints on the presence of new phenomena in nature.

    graph
    These plots show the effective lifetime asymmetries as function of decay time for D →K+K- (top) and D → π+π- (bottom) samples. Results of the fits not allowing for (dotted red line) and allowing for (solid blue line) CP violation are overlaid.

    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 5:20 pm on October 28, 2014 Permalink | Reply
    Tags: , Bs meson, , CP Violation, , , , Syracuse University   

    From Syracuse University: “Syracuse Physicists Closer to Understanding Balance of Matter, Antimatter” 

    Syracuse University

    Syracuse University

    Physicists in the College of Arts and Sciences have made important discoveries regarding Bs meson particles—something that may explain why the universe contains more matter than antimatter.

    ss
    Sheldon Stone

    Distinguished Professor Sheldon Stone and his colleagues recently announced their findings at a workshop at CERN in Geneva, Switzerland. Titled Implications of LHCb Measurements and Their Future Prospects, the workshop enabled him and other members of the Large Hadron Collider beauty (LHCb) Collaboration to share recent data results.

    CERN LHCb New
    CERN LHCb

    The LHCb Collaboration is a multinational experiment that seeks to explore what happened after the Big Bang, causing matter to survive and flourish in the Universe. LHCb is an international experiment, based at CERN, involving more than 800 scientists and engineers from all over the world. At CERN, Stone heads up a team of 15 physicists from Syracuse.

    “Many international experiments are interested in the Bs meson because it oscillates between a matter particle and an antimatter particle,” says Stone, who heads up Syracuse’s High-Energy Physics Group. “Understanding its properties may shed light on charge-parity [CP] violation, which refers to the balance of matter and antimatter in the universe and is one of the biggest challenges of particle physics.”

    Scientists believe that, 14 billion years ago, energy coalesced to form equal quantities of matter and antimatter. As the universe cooled and expanded, its composition changed. Antimatter all but disappeared after the Big Bang (approximately 3.8 billion years ago), leaving behind matter to create everything from stars and galaxies to life on Earth.

    “Something must have happened to cause extra CP violation and, thus, form the universe as we know it,” Stone says.

    He thinks part of the answer lies in the Bs meson, which contains an antiquark and a strange quark and is bound together by a strong interaction. (A quark is a hard, point-like object found inside a proton and neutron that forms the nucleus of an atom.)

    Enter CERN, a European research organization that operates the world’s largest particle physics laboratory.

    In Geneva, Stone and his research team—which includes Liming Zhang, a former Syracuse research associate who is now a professor at Tsinghua University in Beijing, China—have studied two landmark experiments that took place at Fermilab, a high-energy physics laboratory near Chicago, in 2009.

    lhc
    The Large Hadron Collider at CERN

    The experiments involved the Collider Detector at Fermilab (CDF) and the DZero (D0), four-story detectors that were part of Fermilab’s now-defunct Tevatron, then one of the world’s highest-energy particle accelerators.

    “Results from D0 and CDF showed that the matter-antimatter oscillations of the Bs meson deviated from the standard model of physics, but the uncertainties of their results were too high to make any solid conclusions,” Stone says.

    He and Zhang had no choice but to devise a technique allowing for more precise measurements of Bs mesons. Their new result shows that the difference in oscillations between the Bs and anti-Bs meson is just as the standard model has predicted.

    Stone says the new measurement dramatically restricts the realms where new physics could be hiding, forcing physicists to expand their searches into other areas. “Everyone knows there is new physics. We just need to perform more sensitive analyses to sniff it out,” he adds.

    See the full article here.

    Syracuse University was officially chartered in 1870 as a private, coeducational institution offering programs in the physical sciences and modern languages. The university is located in the heart of Central New York, is within easy driving distance of Toronto, Boston, Montreal, and New York City. SU offers a rich mix of academic programs, alumni activities, and immersion opportunities in numerous centers in the U.S. and around the globe, including major hubs in New York City, Washington, D.C., and Los Angeles. The total student population at Syracuse University represents all 50 U.S. states and 123 countries.

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  • richardmitnick 11:43 am on July 15, 2014 Permalink | Reply
    Tags: , , CP Violation, , KEK Laboratory, ,   

    From interactions.org: “KEK: 50 years from the discovery of ‘CP-violation'” 

    Interactionsdotorg

    11 July 2014
    Professor Yoshihide Sakai
    Co-spokesperson, the Belle Collaboration
    The High Energy Accelerator Research Organization

    Public Relations Office, High Energy Accelerator Research Organization (KEK), Japan
    Saeko Okada
    Senior Press Officer, Public Relations Office, KEK
    TEL: +81-29-879-6046
    FAX: +81-29-879-6049
    E-mail: press@kek.jp

    Belle and Babar complete a joint book on their experimental work to prove the Kobayashi-Maskawa theory of CP-violation

    The joint publication was completed last month. To celebrate this achievement, the first special editions of the book are presented to Drs. Cronin, Kobayashi and Maskawa today at the 50 Years of CP Violation conference held in London.

    In 1993 the SLAC National Accelerator Laboratory in California and the KEK laboratory near Tokyo in Japan embarked on a quest to understand the nature of CP violation, a tiny difference between matter and antimatter that is vital for our existence. This effect was discovered in the decay of a particle called a kaon in 1964. These kaons exhibited strange behaviour compared with other particles studied at the time, and we now refer to the quark that causes that behaviour as a strange (or just s) quark. The amount of CP violation in kaon decays is insufficient to explain how the universe came to be dominated by matter.

    SLAC Campus
    SLAC National Accelerator Lab

    KEK lab
    KEK

    SLAC and KEK constructed so called B Factories, which are particle accelerators and detectors to produce a large number of Bottom (or Beauty) particles, which contain b quarks, and study CP violation. The B Factory mission was to explore the phenomenon of CP violation in these particles. Twenty-one years on, these two international collaborations have come to the end of a global collaborative project: one that has produced a weighty tome over 900 pages in length, detailing all aspects of the Physics of the B Factories and their detectors: BaBar and Belle. The physics harvest from the international collaborations that run BaBar and Belle have included many notable discoveries including: CP violation in B decays, first studies of some very rare B decays, and a host of new particles. The breakthroughs have continued more recently with the determination of mixing in neutral charm mesons. This discovery paves the way for the next generation of experiments to search for certain types of CP violation in the decay of charm mesons. Almost a thousand papers have been published by these two experiments during their lifetime.

    The original flagship measurements of the B Factories were found to be consistent with the Cabibbo-Kobayashi-Maskawa matrix description of CP violation. This provides the Standard Model of particle physics with a description of CP violation as predicted by Kobayashi and Maskawa in 1972.

    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.

    The B Factory confirmation of the Kobayashi-Maskawa mechanism was quickly followed by Kobayashi and Maskawa sharing a Nobel Prize (in 2008) for their insightful work. The Cabibbo-Kobayashi-Maskawa matrix is now known to provide the leading description of CP violation. However, while this was an important step forward for the field, the amount of CP violation in the Standard Model remains about a billion times too small to explain the matter-dominated universe that we live in. As a result the focus of the field has turned from understanding how nature behaves to the much more subtle task of trying to understand if there are small deviations from this leading description that have been missed so far.

    A new book has been written as a collaboration between the two teams of physicists working on BaBar and Belle, with the help of the theory community. This is envisioned to be a pedagogical resource for the next generation of experimentalists to work in this field. Preparations started in 2008 and the concept was solidified through a number of international meetings over the past six years. This effort brought together experts from the global flavour physics communities from four continents. The KEK B Factory is in the process of being upgraded and should recommence data taking as a “Super B Factory” with a physics programme resuming in 2016. A decade from now someone will surely need to write a book on the Physics of the Super B Factory.


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  • richardmitnick 6:12 am on September 28, 2013 Permalink | Reply
    Tags: , , CP Violation,   

    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!

    bbe
    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.

    team
    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.

    rack
    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.
    i1


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  • richardmitnick 12:35 pm on March 12, 2013 Permalink | Reply
    Tags: , , , CP Violation, , , , ,   

    From Symmetry: “LHCb studies particle tipping the matter-antimatter scales” 

    March 12, 2013
    Kelly Izlar

    The LHCb experiment at CERN reports precise new measurements—but leaves open the question of why our matter-dominated universe exists.

    lhcb
    LHCb

    “Today, scientists from CERN’s LHCb experiment announced new results in the study of the evolution of our matter-dominated universe.

    The face-off between matter and antimatter was supposed to be a fair fight. The big bang should have created equal quantities of matter and antimatter, which are identical to one another but with some opposite properties such as charge. As matter and antimatter interacted over the past 13 billion or so years, they should have annihilated each other, stripping our young universe of its potential and leaving it a void.

    But scientists think something happened in those first moments to upset the balance, skewing the advantage slightly toward matter.

    Over the past several decades, scientists have found that some particles decay into matter slightly more often than they decay into antimatter. The Standard Model of particle physics predicts a certain amount of this imbalance, called charge parity [CP] violation.

    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.

    However, the points this wins for matter can’t account for the amount of it left over in our universe. In fact, calculations suggest that it’s not enough for even a single galaxy. Since there may be as many as 500 billion galaxies in our universe, something is missing.

    ‘We think there has to be another source of CP violation that you don’t see in the Standard Model,’ says Sheldon Stone, group leader of Elementary Particle Physics at Syracuse University and a member of LHCb. ‘The source of this CP violation can be new forces carried by new particles, or even extra dimensions.’

    Physicists are looking beyond the Standard Model for another source of CP violation that gave rise to galaxies, stars, planets and, eventually, us.

    In 2011, LHCb analysis hinted that the CP violation in D mesons went beyond the amount predicted in the Standard Model, a possible sign of new physics in the works.

    But in results presented today at the Rencontres de Moriond physics conference in Italy, those hints of new physics have melted away, reinforcing the predictions in the Standard Model of particle physics and leaving us with the mystery of why our universe is made of so much matter.

    ‘If we look at it as the glass being half empty, we could be disappointed that the hint for something exciting isn’t confirmed,’ says Tim Gershon, LHCb physics coordinator and professor at the University of Warwick. ‘On the other hand, there was a lot of theoretical work suggesting models to explain effects we’ve seen. New results constrain the models and tell us something about nature.'”

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.


     
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