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Friday, April 22, 2005
Physics Building, Room 204
Note special time.
[Host: Brad Cox]
Ohio State University
"The Asymmetry Between Matter and Anti Matter - or -How to Know if it is Safe to Shake an Alien's Hand?"
Most of us have looked at the spectacular pictures taken by the Hubble Space Telescope. Galaxies, nebulae, super novae -- but there is something peculiar about these images. Where ever we look in space we only see matter. No significant quantities of anti-matter have been found. Since we believe equal amounts of matter and anti-matter have been produced originally we must conclude that there is an asymmetry between particle and anti-particle decays. In the laboratory, however, nature always seems to obey the particle - antiparticle symmetry with one known exception. Almost 40 years ago a small difference has been found in the neutral kaon system. But the nature of this system made it extremely difficult for
both theorists and experimentalists to extract a clear picture of this effect. For years there has been great hope in the particle physics community
that a large matter - antimatter asymmetry can be observed in a new system - the weak decays of massive B mesons. The past decade has seen a vigorous experimental effort to produce the large
quantities of B mesons required to discover the cause of this asymmetry. Particle accelerators have been upgraded and new detectors were
constructed. As we enter the Golden Age of B physics nearly a billion B meson decays have been recorded by these experiments. I will review some
of the old questions that have been answered and discuss some of the new puzzles that have been uncovered.
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