New Measurements of CP Violation in B0 to ccbar K*(0) decays from Babar

Abstract

We present new measurements of CP asymmetries in B{sup 0} {yields} (c{bar c})K{sup 0(*)} decays recorded by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC between 1999 and 2004. We determine sin2{beta} from decay-time distributions of 7730 signal events in a data sample of approximately 227 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays. The measured value of sin2{beta} = 0.722 {+-} 0.040(stat) {+-} 0.023(syst) is in agreement with the value expected from the Standard Model. In a separate time-dependent angular analysis of B {yields} J/{psi} K*{sup 0} (K*{sup 0} {yields} K{sub S}{sup 0}{pi}{sup 0}) decays we measure cos 2{beta} to be positive at 86% CL.