B decay anomalies in an effective theory

Abstract

We investigate how far a new physics scenario affecting primarily the third generation fermions can ameliorate the tension between B-decay observables and Standard Model expectations. Adopting a model-independent approach, we find that among the three observables that show signs of such a tension, viz. the branching fractions for $B^+\to\tau\nu$, $B_d\to D(D^\ast)\tau\nu$, and the like-sign dimuon anomaly in neutral B decays, the first two can be explained adequately, while there is only a marginal improvement for the third. As a spin-off, it is shown that one can also accommodate a change in the branching fraction of the Higgs boson to a $\tau$ lepton pair from the SM expectation, if such a change is established in future data.