Continuing search for new physics in b → sμμ decays: two operators at a time

The anomalies in the measurements of observables involving b → sμμ decays, namely RK, RK*, P5′, and Bsϕ, may be addressed by adding lepton-universality-violating new physics contributions to the effective operators O9,O10,O9′,O10′. We analyze all the scenarios where the new physics contributes to a pair of these operators at a time. We perform a global fit to all relevant data in the b → s sector to estimate the corresponding new Wilson coefficients, O9NP,O10NP,O9′,O10′. In the light of the new data on RK, and RK*, presented in Moriond 2019, we find that the scenarios with new physics contributions to the (O9NPO9′) or (O9NPO10′) pair remain the most favored ones. On the other hand, though the competing scenario (O9NPO10NP) remains attractive, its advantage above the SM reduces significantly due to the tension that emerges between the RK and RK* measurements with the new data. The movement of the RK measurement towards unity would also result in the re-emergence of the one-parameter scenario C9NP = − C9′.