Implications of new evidence for lepton-universality violation in b ?sl+l- decays

Motivated by renewed evidence for new physics in b?sll transitions in the form of LHCb's new measurements of theoretically clean lepton-universality ratios and the purely leptonic Bs?µ+µ- decay, we quantify the combined level of discrepancy with the Standard Model and fit values of short-distance Wilson coefficients. A combination of the clean observables RK, RK*, and Bs?µµ alone results in a discrepancy with the Standard Model at 4.0s, up from 3.5s in 2017. One-parameter scenarios with purely left-handed or with purely axial coupling to muons fit the data well and result in a ~5s pull from the Standard Model. In a two-parameter fit of new-physics contributions with both vector and axial-vector couplings to muons the allowed region is much more restricted than in 2017, principally due to the much more precise result on Bs?µ+µ-, which probes the axial coupling to muons. Including angular observables data restricts the allowed region further. A by-product of our analysis is an updated average of BR(Bs?µ+µ-)=(2.8±0.3)×10-9.