My
research is concentrated mainly on studies of the properties of the
charmed quark (c-quark) and the beauty quark (b-quark).
Studies of the weak decays of particles that contain a b-quark
have proven to be extremely useful for investigating the detailed
properties of the Weak Interactions. These studies proved crucial
to establishng the correct framework for incorporating matter-antimatter
asymmetries, called CP violation, into the WEak Interatction theory.
Our measurements of differences between the decays of mesons containing
b-quarks and those containing anti-b-quarks proved the validity
of the theory first proposed in 1973 by Makoto Kobayashi and Toshihide
Makawa and led to their receipt of the 2008 Nobel physics prise.
Studies of particles containing c-quarks have led to a better
understanding of how quarks combine to form particles. When first
proposed in 1964, quarks were considered to be mathematical constructs
that were useful for classifying the various known sub-atomic particles.
This changed abruptly in 1974, when the J/psi particle, which we
now know to be comprised of a c- and anti-c-quark. Subsequently,
related particles were found that could be nicely classified as
different quantum states of the c anti-c bound state system, the
so-called charmonium mesons. At this time it was realized that quarks
are real physical objects. Studies of the charmonium meson system
--sometimes called the hydrogen atom of the strong interactions--
have provided a wealth of information about how quarks and particles
are interrelated. Recently, a number of charmonium-like particles
have been discovered that do not fit the c-quark anti-c-quark classification
scheme. These are indications of possible new types of particles,
which, so far, seem to have theoretical physicists baffled.
The best facility in the world for studying b-quarks is at the
KEK laboratory in Japan; the world's best c-quark facility at the
Institute of High Energy Physics in Beijing. Our group does experiments
at both places.