First flavor-tagged determination of bounds on mixing-induced CP violation in Bs0→J/ψφ decays

This Letter describes the first determination of bounds on the CP-violation parameter 2 beta(s) using B-s(0) decays in which the flavor of the bottom meson at production is identified. The result is based on approximately 2000 B-s(0) -> J/psi phi decays reconstructed in a 1.35 fb(-1) data sample collected with the CDF II detector using p (p) over bar collisions produced at the Fermilab Tevatron. We report confidence regions in the two-dimensional space of 2 beta(s) and the decay-width difference Delta Gamma. Assuming the standard model predictions of 2 beta(s) and Delta Gamma, the probability of a deviation as large as the level of the observed data is 15%, corresponding to 1.5 Gaussian standard deviations.