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Events in Physics
Title: Matter-Antimatter Transformations At 3 Trillion Hertz    (Colloquia)
Start Date: 04/23/2007
Time: 4:30 pm
Location: 1 LeConte
Speaker: Joseph Kroll

We have known for 50 years that certain types of neutral mesons
(subatomic particles consisting of a quark and an antiquark bound by the
strong interaction) can transform via the weak interaction from particle to
antiparticle. The study of these transformations has led to many important
findings including the discovery of the violation of the combined symmetry
operation of Charge conjugation and Parity (CP Violation), which is one of the
necessary conditions to create the matter-antimatter asymmetry in the Universe.

The strange neutral B meson consists of a heavy bottom antiquark bound with a strange quark. In the late 1980's, experiments established that the strange
B meson transforms very rapidly to its antiparticle. The transformation rate
is so large that it has eluded direct measurement until recently.
I will present the first measurement of this transformation rate
from the CDF experiment at the Fermilab Tevatron collider.
This result sets the stage for examining extensions of the standard model
of particle physics and for further investigations of CP Violation.