Particle Physics Seminar

The Belle experiment has measured several instances of
CP violation in the B meson system. These measurements allow
one to determine the internal angles $\phi_1$, $\phi_2$, and
$\phi_3$ (or $\beta$, $\alpha$, and $\gamma$) of the CKM unitarity
triangle. Within their errors, the values obtained satisfy the
triangle relation $\phi_1 + \phi_2 + \phi_3 = 180$ degrees.
The angle $\phi_1$ is also determined from several
$b\rightarrow s\bar{q}q$ penguin-dominated decay modes; the
value obtained by taking a weighted average of the individual
results differs from the $B^0\rightarrow J/\psi\,K^0$ result
by more than two standard deviations. The angle $\phi_2$
is constrained by measuring a CP asymmetry in the decay
time distribution of $B^0\rightarrow\pi^+\pi^-$ decays;
the asymmetry observed is large, and the difference in
the yields of $B^0/\overline{B}{}^{\,0}$ decays constitutes
the first evidence for direct CP violation in the B system.