B Flavor Anomalies: 2021 Theoretical Status Report

Abstract

At the present time (2022), there are discrepancies with the predictions of the Standard Model in several observables involving b → sℓ+ℓ− and [Formula: see text] decays. These are the B flavor anomalies. In this review, we summarize the data as of Moriond 2021 and present theoretical new physics explanations from both a model-independent effective field theory point of view and through the building of explicit models. Throughout, we stress the complementarity of these two approaches. In addition, we discuss combined explanations of both B anomalies and present models that also explain other problems, such as dark matter, ( g − 2)μ, neutrino properties, and hadronic anomalies.