Constraints on the charged scalar effects using the forward-backward asymmetry on $B\to D^{(\ast )}\tau \overline{{\nu }_{\tau }}$

Abstract

The decay modes $\bar{B}\to D^{(\ast )}\tau {\bar{\nu }}_{\tau }$ are sensitive to charged scalar effects, such as the charged Higgs effects. In this paper we suggest a method to determine their effects by using the ratio of branching fractions and forward-backward asymmetries. In particular, forward-backward asymmetries on $\bar{B}\to D^{(\ast )}\tau (\to \pi {\nu }_{\tau }){\bar{\nu }}_{\tau }$, $\bar{B}\to D^{(\ast )}\tau (\to \rho {\nu }_{\tau }){\bar{\nu }}_{\tau }$, and $\bar{B}\to D^{(\ast )}\tau (\to a_1{\nu }_{\tau }){\bar{\nu }}_{\tau }$ play an important role, which discriminate the Standard Model from other New Physics scenarios.

Comments: 8 pages, 7 figures. The Results of forward-backward asymmetry on B->D(*)pi nu nu, B->D(*)rho nu nu, and B->D(*)a1 nu nu added