Current Status of the Standard Model Prediction for the B_s -> mu^+ mu^- Branching Ratio

Abstract

The rare decay B_s -> mu^+ mu^- provides an important constraint on possible deviations from the Standard Model in b-s-l-l interactions. The present weighted average of its branching ratio measurements amounts to (3.34 \pm 0.27) x 10^-9, which remains in good agreement with the theoretical prediction of (3.64 \pm 0.12) x 10^-9 within the Standard Model. In the present paper, we review calculations that have contributed to this prediction, and discuss the associated uncertainties.

Comments: 20 pages, 5 figures. Contribution to the "Symmetry" Special Issue "Symmetries and Anomalies in Flavour Physics"