Interpreting Hints for Lepton Flavor Universality Violation

We interpret the recent hints for lepton flavor universality violation in rareB meson decays. Based on a model-independent effective Hamiltonian approach, we determine regions of new physics parameter space that give a good description of the experimental data on RK and RK∗ , which is in tension with Standard Model predictions. We suggest further measurements that can help narrowing down viable new physics explanations. We stress that the measured values of RK and RK∗ are fully compatible with new physics explanations of other anomalies in rare B meson decays based on the b→ sμμ transition. If the hints for lepton flavor universality violation are first signs of new physics, perturbative unitarity implies new phenomena below a scale of ∼ 100 TeV.