Observation of CP violation in the B0 system

Abstract

The BABAR detector, operating at energies near the ?(4S) resonance at the PEP-II asymmetric B Factory at SLAC, has collected a sample of 32 million BB pairs by May 2001. A study of time-dependent CP-violating asymmetries in events where one neutral B meson is fully reconstructed in a final state containing charmonium has resulted in the measurement sin2ß = 0.59±0.14 (stat)±0.05 (syst), which establishes CP violation in the B0 meson system at the 4s level. B lifetime and mixing measurements from a sub-sample of 23 million BB pairs are also presented.