Bdecay 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 ${B}^{+}\ensuremath{\rightarrow}\ensuremath{\tau}\ensuremath{\nu}$, ${B}_{d}\ensuremath{\rightarrow}D({D}^{*})\ensuremath{\tau}\ensuremath{\nu}$, 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 $\ensuremath{\tau}$ lepton pair from the Standard Model expectation, if such a change is established in future data.