Flavor anomalies on the eve of the Run-2 verdict

International audienceThe RK measurement by LHCb suggests nonstandard Lepton-Universality Violation (LUV) to occur in b → sℓ+ℓ− decays with effects in muons rather than electrons. It is intriguing that a number of other measurements of b → sℓ+ℓ− transitions by LHCb and B-factories are consistent in magnitude and sign with the RK effect, and fit a coherent effective-theory picture. Further indications of nonstandard LUV are provided by the long-standing discrepancies in b → cτν transitions via the ratios R(D) and R(D∗). We review in detail the experimental situation and its rich outlook, the theoretical efforts — and their challenges — towards convincing dynamics beyond the effective-theory level, and discuss the many directions of further investigation that propagate from the current situation