Global fits to b → sℓℓ data and signs for lepton non-universality

Abstract

There are some slight tensions with the SM predictions within the latest LHCb measurements. Besides the known anomaly in one angular observable of the rare decay B → K*μ+μ−, another small discrepancy recently occurred. The ratio RK = BR(B+ → K+μ+μ−)/BR(B+ → K+e+e−) in the low-q2 region has been measured by LHCb showing a 2.6σ deviation from the SM prediction. In contrast to the anomaly in the rare decay B → K*μ+μ− which is affected by power corrections, the ratio RK is theoretically rather clean. We analyse all the b → sℓℓ data with global fits and in particular explore the possibility of breaking of lepton universality. Possible cross-checks with an analysis of the inclusive B → Xsℓ+ℓ− decay are also explored.