  B mesons provide an ideal laboratory for measurements of CP violation and
searches for CP violation beyond the Standard Model. Recent measurements of the
mixing phases of the $B_s^0$ and $B^0$ mesons, $\phi_s$ and $\sin2\beta$, using
decays to $J/\psi X$ final states are presented. In view of future improved
measurements, a good understanding of pollution from sub-leading penguin
topologies in these decays is needed. Those can be probed using suppressed
decays like $B_s^0 \to J/\psi K_S^0$ and $B_s^0 \to J/\psi \overline{K}^{*0}$.
Recent results using these decay modes are presented.
