Measurement of CP violation in the $B_s^0$ system

Studies of CP violation play a key role in the search for physics beyond the Standard Model. In the $B_s^0$ system these mainly consist of measurements of mixing-induced CP violation, which arises from the interference between the $B_s^0$-$\bar{B}_s^0$ mixing process and the subsequent decay. This report focusses on two such asymmetry measurements recently published by the LHCb collaboration. The first analysis presents the measurement of a CP violating phase in $B_s^0\to\phi\phi$, which is found to be $\phi_{\phi\phi} = -0.17 \pm 0.15\:(\text{stat}) \pm 0.03\:(\text{syst})\:\text{rad}$. The second provides an updated measurement of the $B_s^0$-$\bar{B}_s^0$ mixing phase $\phi_s$ using the $B_s^0\to J/\psi\pi^+\pi^-$ channel. It yields $\phi_s = 0.070 \pm 0.068\:(\text{stat}) \pm 0.008\:(\text{syst})\:\text{rad}$. Both results are consistent with the Standard Model expectations and no indication for direct CP violation was found in either decay mode.