CP violation in the Bs0 system

Experimental and theoretical studies of CP violation in the Bs0 system are reviewed. Updated predictions for the mixing parameters of the Bs0 mesons expected in the standard model (SM) are given, namely, the mass difference ΔMsSM=18.3±2.7 ps-1, the decay rate difference ΔΓsSM=0.085±0.015 ps-1, and the flavor-specific CP asymmetry afss,SM=(2.22±0.27)×10-5 and the equivalent quantities in the B0 sector. Current experimental values of ΔMs and ΔΓs agree with remarkable precision with theoretical expectations. This agreement supports the applicability of theoretical tools such as the heavy quark expansion to these decays. CP-violating studies in the Bs0 system provide essential information to test the SM expectations and to unveil a possible contribution of the new physics (NP). NP effects on ΔMs of the order of 15% are still possible. The CP phase φs due to CP violation in interference of decays and mixing can accommodate effects of the order of O(100%). The semileptonic CP asymmetry asls due to CP violation in mixing could still be a factor of 130 larger than its robust SM expectation and thus provides a very clean observable for NP searches. Theoretical improvements that are necessary to make full use of the experimental precision are discussed.