Abstract

The $B0_s$ mixing phase $\beta_s$ is a key probe of physics beyond the standard model (SM). The first Tevatron measurements hinted at a $\approx 2\sigma$ departure from the SM expectations. We present a new analysis using $B_s0 \rightarrow J/\psi\,\phi$ decays reconstructed in 5.2~fb$^{-1}$ of data collected by CDF detector, where tightened bounds on the mixing phase are obtained along with an improved measurement of the decay-width difference $\Delta \Gamma_s$ and of $B0_s$ lifetime.