CP violation at BABAR
The B0 and anti-B0 meson behave differently when they decay, and this provides a measure of CP violation in the Standard Model. The decay rate of (a) the B0 and (b) the anti-B0 meson are exponential curves. But CP violation, combined with the propensity for
B0 and anti-B0 mesons to "mix", causes these exponentials to be modified by a sine wave. This sinusoidal behaviour changes sign between the B0 and anti-B0 meson, as can be seen in the shape of their decay rates. (c) By dividing the difference between the two decay rates by their sum, this asymmetry can be obtained, which provides a direct measurement of the angle β in the unitarity triangle.