We present results on time-dependent CP asymmetries in neutral B decays. The amplitude of the CP asymmetry, sin2β in the Standard Model, is derived from decay-time distributions from events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the other B meson is determined to be either a B0 or B̄0 from its decay products. Using data collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC, we measure sin2β = 0.722 ± 0.040(stat) ± 0.023(syst) and cos2β = 2.72-0.79 +0.50(stat) ± 0.27(syst), determining the sign of cos2β to be positive at 86% CL.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Nuclear and High Energy Physics
- Astronomy and Astrophysics