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 $B^{+}\to \tau \nu$, $B_d\to D(D^{*})\tau \nu$, 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 Standard Model expectation, if such a change is established in future data.

• Received 5 November 2012

DOI:https://doi.org/10.1103/PhysRevD.86.114037