Understand
We re-visit the problem of New Physics (NP) contribution to the branching ratio of the $B_s \to \mu^+ \mu^-$ decay in light of the recent observation of this decay by LHCb.
- We consider R-parity violating (RPV) supersymmetric models as a primary example - recently one has reported stringent constraints on the products of the RPV coupling constants that account for the $B_s \to \mu^+ \mu^-$ transition at the tree level.
- We argue that despite the LHCb measurement of the $B(B_s \to \mu^+ \mu^-)$ is in a remarkable agreement with the Standard Model (SM) prediction, there is still room for a significant New Physics contribution to the $B(B_s \to \mu^+ \mu^-)$, as the sign of the $B_s \to \mu^+ \mu^-$ transition amplitude may be opposite to that of the Standard Model; alternatively the amplitude may have a large phase.
- We conduct our analysis mainly for the case of real RPV couplings.