Theory Status - Puzzles in B Meson Decays and LFU?

Abstract

Currently B meson puzzles motivate many studies of New Physics due to the observed deviations from the Standard Model predictions. There are two B meson puzzles, R_{D^{(*)}}RD(*) and R_{K^{(*)}}RK(*). The first one denotes the deviations in the decays driven by the charged current in the ratio of the decay widths for B \to D^{(*)} \tau \nuB→D(*)τν and B \to D^{(*)} \mu \nuB→D(*)μν, while the second one is related to the ratio of the decay widths for B \to K^{(*)} \mu^+ \mu^-B→K(*)μ+μ− and B \to K^{(*)} e^+ e^-B→K(*)e+e− transition. Also, the measured muon anomalous magnetic moment differs from the SM predictions. Usually, the effective Lagrangian approach containing New Physics effects is used to analyse R_{D^{(*)}}RD(*) and R_{K^{(*)}}RK(*). Among many models of New Physics, various leptoquark models are suggested to resolve both B meson anomalies. If New Physics is confirmed in B decays a number of processes at low and high energies should confirm its presence.