Improved Measurement of CP Violation in Neutral B Decays to c¯cs

We present updated measurements of time-dependent C P asymmetries in fully-reconstructed neutral B decays to several C P eigenstates containing a charmonium meson. The measurements use a data sample of ( 383 ± 4 ) × 10 6 Υ ( 4 S ) → B ¯¯¯ B decays collected with the BABAR detector at the PEP-II B factory. We determine sin  2 β = 0.714 ± 0.032 ( stat ) ± 0.018 ( syst ) and | λ | = 0.952 ± 0.022 ( stat ) ± 0.017 ( syst )