B-physics performance of the CMS detector

We describe the CMS detector, with special attention to its microvertex pixel detector. Then, we discuss the potential of the CMS detector for the study of CP violation; the sensitivity to the unitarity triangle angle β obtained from the Bd0 → JψKs0 channel is 0.048 from a time-integrated analysis and 0.046 from a time-dependent analysis; the corresponding values for the angle α obtained from the Bd0 → π+π− channel are 0.050 and 0.070, respectively. We also discuss the possibilities to observe Bs0 oscillations and some rare decays.