B decays with $\tau$-leptons in non-universal left-right models

Abstract

Recent measurements of semileptonic $B$-meson decays into $\tau$-leptons are somewhat higher than expected in the standard model. Although the deviations are less than 3$\sigma$, they suggest the possibility of new physics affecting primarily the $\tau$-lepton. In this paper we examine these results within the context of non-universal left-right models. We find that strong constraints from $b\to s\gamma$ on $W-W^{\prime }$ mixing lead to a prediction of approximately equal enhancements for the $B\to D\tau \nu$ and the $B\to D^{\star }\tau \nu$ modes. The model predicts approximately the same enhancement for the inclusive semileptonic rate $\bar{B}\to X_c\tau \nu$ as well as for the leptonic decay $B_c^{-}\to {\tau }^{-}\nu$. An enhancement in the leptonic decay $B^{-}\to {\tau }^{-}\nu$ is also possible but is not uniquely correlated with the other modes. For this explanation to be viable, the mass of the non-universal $W^{\prime }$ would be below 1 TeV, within LHC reach.

Comments: 12 pages, no figure