Download or read book Improved Measurement of the CP-Violating Asymmetry Amplitude Sin2beta written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present updated results on time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 62 million [Upsilon](4S) [yields] B[bar B] decays collected between 1999 and 2001 by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. In this sample we study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin2[beta], is derived from the decay time distributions in such events. We measure sin2[beta] = 0.75 [+-] 0.09 (stat) [+-] 0.04 (syst) and lambda = 0.92 [+-] 0.06 (stat) [+-] 0.02 (syst). The latter is consistent with the Standard Model expectation of no direct CP violation. These results are preliminary.