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

Abstract The anomalies in the measurements of observables involving b → sμμ decays, namely R K , R K*, P 5 ′ , and B s ϕ , may be addressed by adding lepton-universality-violating new physics contributions to the effective operators O 9 , O 10 , O 9 ′ , O 10 ′ $$ {\mathcal{O}}_{\mathcal{9}},{\mathcal{O}}_{10},{\mathcal{O}}_9^{\prime },{\mathcal{O}}_{10}^{\prime } $$ . 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, O 9 N P , O 10 N P , O 9 ′ , O 10 ′ $$ {\mathcal{O}}_9^{\mathrm{NP}},{\mathcal{O}}_{10}^{\mathrm{NP}},{\mathcal{O}}_9^{\prime },{\mathcal{O}}_{10}^{\prime } $$ . In the light of the new data on R K , and R K*, presented in Moriond 2019, we find that the scenarios with new physics contributions to the O 9 N P O 9 ′ $$ \left({\mathcal{O}}_9^{\mathrm{NP}},{\mathcal{O}}_9^{\prime}\right) $$ or O 9 N P O 10 ′ $$ \left({\mathcal{O}}_9^{\mathrm{NP}},{\mathcal{O}}_{10}^{\prime}\right) $$ pair remain the most favored ones. On the other hand, though the competing scenario O 9 N P O 10 N P $$ \left({\mathcal{O}}_9^{\mathrm{NP}},{\mathcal{O}}_{10}^{\mathrm{NP}}\right) $$ remains attractive, its advantage above the SM reduces significantly due to the tension that emerges between the R K and R K* measurements with the new data. The movement of the R K measurement towards unity would also result in the re-emergence of the one-parameter scenario C 9 NP  = − C 9 ′ .