First Flavor-Tagged Determination of Bounds on Mixing-Induced CP Violation in B^0_s --] J/psi Phi Decays

Book excerpt: This Letter describes the first determination 1 of bounds on the CP-violation parameter 2[beta]{sub s} using B{sub s}° decays in which the flavor of the bottom meson at production is identified. The result is based on approximately 2, 000 B{sub s}° → J/[psi][phi] decays reconstructed in a 1.35 fb−1 data sample collected with the CDFII detector using p{bar p} collisions produced at the Fermilab Tevatron. We report confidence regions in the two-dimensional space of 2[beta]{sub s} and the decay-width difference [Delta][Lambda]. Assuming the standard model predictions of 2[beta]{sub s} and [Delta][Lambda], the probability of a deviation as large as the level of the observed data is 15%, corresponding to 1.5 Gaussian standard deviations.