CP violation in the Bs0 system

Abstract

Experimental and theoretical studies of CP violation in the B0s system are reviewed. Updated predictions for the mixing parameters of the B0s mesons expected in the standard model (SM) are given, namely, the mass difference ΔMSMs=18.3±2.7 ps−1, the decay rate difference ΔΓSMs=0.085±0.015 ps−1, and the flavor-specific CP asymmetry as,SMfs=(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 B0s 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 assl 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.