On the Standard Model prediction for BR(B{s,d} to mu+ mu-)

Understand

The decay Bs to mu+ mu- is one of the milestones of the flavor program at the LHC.

• We reappraise its Standard Model prediction.
• First, by analyzing the theoretical rate in the light of its main parametric dependence, we highlight the importance of a complete evaluation of higher-order electroweak corrections, at present known only in the large-mt limit, and leaving sizable dependence on the definition of electroweak parameters.
• Using insights from a complete calculation of such corrections for K to pi bar{nu} nu decays, we find a scheme in which NLO electroweak corrections are likely to be negligible.