Effect of H^\pm on B^\pm\to τ^\pmν_τand D^\pm_s\to μ^\pmν_μ,τ^\pmν_τ

Abstract

The recent observation of the purely leptonic decay B^\pm\to τ^\pmν_τat the B factories permits a sizeable contribution from a charged Higgs boson (H^\pm). Such a H^\pm would also contribute to the decays D^\pm_s\to μ^\pmν_μand D^\pm_s\to τ^\pmν_τ, which are being measured with increasing precision at CLEO-c. We show that the branching ratios of D^\pm_s\to μ^\pmν_μand D^\pm_s\to τ^\pmν_τcould be suppressed by up to 10% from the Standard Model prediction, which is larger than the anticipated precision in the measurements of these decays at forthcoming BES-III.