$CP$ violation in $B_s^0$ decays at LHCb

Abstract: Latest LHCb measurements of $CP$ violation in the interference between mixing and decay are presented based on $pp$ collision data collected during LHC Run I, corresponding to an integrated luminosity of $3.0\, {\rm fb}^{-1}$. Approximately $27\, 000$ $B_s^0\to J/\psi \pi^+\pi^-$ signal events are used to make what is at the moment the most precise single measurement of the $CP$-violating phase in $b\to c\bar{c}s$ transitions, $\phi_s^{c\bar{c}s}=0.070\pm0.068{\rm (stat.)}\pm0.008{\rm (syst.)}$ rad. The most accurate measurement of the $CP$-violating phase in $b\to s\bar{s}s$ transitions, $\phi_s^{s\bar{s}s}$, is found from approximately $4\, 000$ $B_s^0\to \phi\phi$ signal events to be $\phi_s^{s\bar{s}s}=-0.17\pm{\rm (stat.)}0.15\pm0.03{\rm (syst.)}$ rad.