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  • richardmitnick 2:54 pm on February 18, 2014 Permalink | Reply
    Tags: , , SLAC BaBar,   

    From Symmetry: “BaBar still breaking new ground” 

    February 18, 2014
    Lori Ann White

    Twenty years after a cutting-edge particle physics experiment at SLAC adopted a royal elephant from a series of children’s books as its mascot, BaBar (the experiment, not the elephant) is still looking ahead to future discoveries.

    SLAC Babar
    BaBar

    In the two decades since its formal inception, the particle physics experiment known as BaBar has gone far beyond its original scientific goal: studying charge-parity violation, which is one method the universe uses to play favorites by showing a preference for matter over antimatter.

    But the agenda of BaBar’s 20th anniversary collaboration meeting in Frascati, Italy, last December, did not consist of three days of researchers patting themselves on the back. They were too busy preparing further data analyses and future proposals.

    BaBar Spokesman Michael Roney, a particle physics professor from the University of Victoria, says that the hundreds of scientists who have belonged to the international collaboration have published more than 500 scientific papers in the past two decades, discussing everything from newly discovered types of mesons (a particle made of a quark and an antiquark) to coming to grips with Big Data before it even had a name.

    The one thing they haven’t done is combine their data with data from their competition, Belle, a Japanese experiment that ran at the same time and also provided valuable data about charge-parity violation.

    Until now.

    The term competition is a little strong, says Roney: Having two different experiments pursue the same goal is a vital part of the scientific process. “Originally, it was important for Belle and BaBar to maintain their independence from each other so each experiment could serve as a check on the other,” he says. “But there are certain issues where neither experiment has enough data to make a definitive statement.”

    To solve that problem, Markus Röhrken, a post-graduate researcher at the California Institute of Technology and a relatively new BaBar-ian, will bring the Belle and BaBar datasets together for the first time. He’s on a hunt for aspects of charge-parity violation that could yield totally new physics beyond the Standard Model.

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    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.

    Combining the data is more complicated than it sounds. “The physics behind BaBar and Belle is exactly the same,” Röhrken says, “but the detectors, the software, the experiments themselves are very different.” Roehrken must become expert in both experiments; while he was a graduate student at Karlsruhe Institute of Technology in Germany, his PhD work was done on Belle, so he’s already half-way there.

    “It’s very unusual for two different collaborations to combine the data itself for analyses,” Roney says. “It’s much more common to combine published results.”

    But Röhrken has his own motivations for pursuing this. Japan is planning a follow-up to Belle, Belle 2, but it isn’t scheduled to start taking data until 2016 at the earliest.

    “I didn’t want to just wait for four or five years to work on these questions,” he says. “I want to look for new physics.

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.



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  • richardmitnick 2:08 pm on November 19, 2012 Permalink | Reply
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    From SLAC: “BaBar Experiment Confirms Time Asymmetry” 

    “Time marches relentlessly forward for you and me; watch a movie in reverse, and you’ll quickly see something is amiss. But from the point of view of a single, isolated particle, the passage of time looks the same in either direction. For instance, a movie of two particles scattering off of each other would look just as sensible in reverse – a concept known as time reversal symmetry.

    Now the BaBar experiment at the Department of Energy’s (DOE) SLAC National Accelerator Laboratory has made the first direct observation of a long-theorized exception to this rule.

    babar
    BaBar

    Digging through nearly 10 years of data from billions of particle collisions, researchers found that certain particle types change into one another much more often in one way than they do in the other, a violation of time reversal symmetry and confirmation that some subatomic processes have a preferred direction of time.

    Reported this week in the journal Physical Review Letters, the results are impressively robust, with a 1 in 10 tredecillion (1043) or 14-sigma level of certainty – far more than needed to declare a discovery.

    ‘It was exciting to design an experimental analysis that enabled us to observe, directly and unambiguously, the asymmetrical nature of time,’ said BaBar collaborator Fernando Martínez-Vidal, associate professor at the University of Valencia and member of the Instituto de Fisica Corpuscular (IFIC), who led the investigation. ‘This is a sophisticated analysis, the kind of experimental work that can only be done when an experiment is mature.’”

    See the full article here.

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.


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  • richardmitnick 1:47 pm on June 18, 2012 Permalink | Reply
    Tags: , , , SLAC BaBar,   

    From SLAC Today: “BaBar Data Hint at Cracks in the Standard Model” 

    June 18, 2012
    Lori Ann White

    “Recently analyzed data from the BaBar experiment may suggest possible flaws in the Standard Model of particle physics, the reigning description of how the universe works on subatomic scales. The data from BaBar, a high-energy physics experiment based at SLAC, show that a particular type of particle decay called “B to D-star-tau-nu” happens more often than the Standard Model says it should.


    Standard Model with the hypothetical Higgs boson

    In this type of decay, a particle called the B-bar meson decays into a D meson, an antineutrino and a tau lepton. While the level of certainty of the excess (3.4 sigma in statistical language) is not enough to claim a break from the Standard Model, the results are a potential sign of something amiss and are likely to impact existing theories, including those attempting to deduce the properties of Higgs bosons.


    Babar

    ‘The excess over the Standard Model prediction is exciting,’ said BaBar spokesperson Michael Roney, professor at the University of Victoria in Canada. The results are significantly more sensitive than previously published studies of these decays, said Roney. ‘But before we can claim an actual discovery, other experiments have to replicate it and rule out the possibility this isn’t just an unlikely statistical fluctuation.'”

    How cool is this!! See the full article here.

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
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  • richardmitnick 12:35 pm on February 14, 2012 Permalink | Reply
    Tags: , , SLAC BaBar,   

    From SLAC Today: “SLAC Physicists Build Prototype of Particle Identification Detector” 

    February 14, 2012
    Lori Ann White

    “The technology behind the photon camera at the heart of BaBar’s Detection of Internally Reflected Cherenkov light (DIRC) detector is getting an upgrade thanks to Jaroslav (Jerry) Va’vra, SLAC detector physicist. With help from Italian mechanical engineer Massimo Benettoni and SLAC technician Matt McCulloch, Va’vra converted the DIRC’s simple pinhole camera into a camera with sophisticated, solid fused-silica optics, while shrinking it to 1/25th its former size and enabling it to collect data 10 times faster.

    The resulting Focused Detection of Internally Reflected Cherenkov light (FDIRC) detector represents an important technical advance in high-energy physics detector science.

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    Jerry Va’vra, SLAC detector physicist, buffs the large block of fused silica that will focus photons of Cherenkov light toward photon detectors that will capture them in the prototype of the Focused Detection of Internally Reflected Cherenkov light detector being built in Building 121. The FDIRC will enable high-energy physicists to decipher the types of particles that generated the Cherenkov light in the first place.

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    Jerry Va’vra, SLAC detector physicist, shows a block of fused silica that will direct captured photons of Cherenkov light toward the focusing block in the prototype of the Focused Detection of Internally Reflected Cherenkov light detector being built in Building 121.

    See the full article here.

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
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  • richardmitnick 5:35 pm on February 2, 2012 Permalink | Reply
    Tags: , , , , SLAC BaBar,   

    From SLAC Today: “BaBar Extends the Search for New Matter-Antimatter Asymmetries” 

    February 2, 2012
    Lori Ann White

    “The BaBar collaboration’s detailed studies of the subtle ways in which matter behaves differently from antimatter are hailed as one of the success stories of experimental high-energy physics. After all, BaBar data and measurements have confirmed a nearly 40-year-old theory that explained the asymmetry between matter and antimatter, and helped convince the Nobel Prize committee to award the 2008 Nobel Prize in Physics to Makoto Kobayashi and Toshihide Maskawa, the two Japanese developers of that theory.

    But BaBar’s SLAC-based search for matter-antimatter asymmetries did not end there. Perhaps Kobayashi’s and Maskawa’s theory, which is now part of the Standard Model of particles and interactions, is not the whole story.

    ‘We know our current picture of particle physics, the Standard Model, cannot be complete, as it vastly underestimates the universe’s matter-antimatter asymmetry,’ said Aaron Roodman of SLAC and Stanford’s Kavli Institute for Particle Astrophysics and Cosmology. ‘Some new source of asymmetry in particle interactions or decays must exist.’ “

    See the rest of the article here.

    So, just what is BaBar?

    “For each particle of matter there exists an equivalent particle with opposite quantum characteristics, called an anti-particle. Particle and anti-particle pairs can be created by large accumulations of energy and, conversely, when a particle meets an anti-particle they annihilate with intense blasts of energy. At the time of the big-bang, the large accumulation of energy must have created an equal amount of particles and anti-particles. But in everyday life we do not encounter anti-particles. The question, therefore, is “What has happened to the anti-particles?”

    bc
    BaBar Detector

    BABAR is a High Energy Physics experiment located at SLAC National Accelerator Laboratory, near Stanford University, in California.

    The goal of the experiment is to study the violation of charge and parity (CP) symmetry in the decays of B mesons. This violation manifests itself as different behaviour between particles and anti-particles and is the first step to explain the absence of anti-particles in everyday life.

    To study CP violation the BABAR experiment exploits the 9.1 GeV electron beam and the 3 GeV positron beam of the PEP-II accelerator. The two beams collide in the center of the experiment, producing Υ(4S) mesons which decay into equal numbers of B and anti-B mesons.

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science. i1

     
  • richardmitnick 2:26 pm on December 5, 2011 Permalink | Reply
    Tags: , , , , , SLAC BaBar,   

    From SLAC Today: “BaBar Studies Matter-Antimatter Asymmetry in Tau Lepton Decays” 

    “December 5, 2011
    Lori Ann White

    Since 1999, physicists from the BaBar experiment at SLAC National Accelerator Laboratory have been studying a fundamental question about the universe – why does it contain so much more matter than antimatter? The laws of physics are remarkably symmetric, affecting both matter and antimatter almost identically.

    But the very existence of the matter around us demonstrates that these laws show a slight, but clear, bias toward matter. The BaBar team should know. They’ve used the data they collected for nine years to study a particular example of this cosmic favoritism – what’s called a matter-antimatter asymmetry in the decays of bottom and anti-bottom quarks.

    BaBar physicists are continuing to exploit the data in various new ways. This includes studies of matter-antimatter asymmetries in other particles than bottom quarks, where the potential for major discovery is still untapped.”

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    The PEP rings and the BaBar Detector

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    See the full article here.

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
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