B->tau nu in multi-Higgs models with MFV

Abstract

We analyse the $B\to \tau \nu$ decay in a generic two-Higgs doublet model satisfying the MFV hypothesis. In particular, we analyse under which conditions $\text{BR}(B\to \tau \nu )$ can be substantially enhanced over its SM value, taking into account the constraints of $K\to \mu \nu$, $B\to X_s\gamma$, and $B_s\to {\mu }^{+}{\mu }^{-}$. We find that for large $\tan \beta$ values and Peccei-Quinn symmetry breaking terms of $\text{cO}(1/\tan \beta )$ a sizable ($\sim 50$) enhancement of $\text{BR}(B\to \tau \nu )$ is possible, even for $m_H\sim 1$ TeV.

Comments: 5 pages, latex, 4 figs. Discussion of B->Xs gamma bound and corresponding numerical analysis significantly improved. Main conclusions unchanged