Search For New Physics at BABAR

Abstract

Using a full BABAR data sample of 426 $f{b}^{-1}$, we present improved measurements of the ratio $\mathcal{R}(D^{(\ast )})=\mathcal{B}(\bar{B}\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau })/$ $\mathcal{B}(\bar{B}\to D^{(\ast )}{\ell }_{\ell }^{-}{\bar{\nu }}_{\ell })$, where $\ell$ is either electron or muon. We measure $\mathcal{R}(D)=0.440\pm 0.058\pm 0.042$ and $\mathcal{R}(D^{\ast })=0.332\pm 0.024\pm 0.018$. These ratios exceed the Standard Model predictions by $2.0\sigma$ and $2.7\sigma$, respectively. The results disagree with the Standard Model predictions at the level of $3.4\sigma$. The ratios are sensitive to new physics contributions in the form of a charged Higgs boson. However, the access cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model.

Comments: Contributed to the Proceedings of Hadron Collider Physics Symposium 2012, Kyoto, Japan, November 12-16 2012