Angular distribution asymmetry in τ^-→π^-π⁰ν_τ decay in the two-Higgs-doublet model with large tan⁡β

We study possible scalar type interactions in τ^-→π^-π⁰ν_τ decay. One finds that an angular distribution asymmetry, A(s), can be induced from the interference between the scalar part and vector part amplitudes in this decay. Our analysis shows that, in the two-Higgs-doublet model of type II with large tan⁡β, the charged Higgs contribution could make A(s) up to 4×10^-3 without conflict with present experimental constraints. Thus in the future precise experiments in τ-charm factories, this angular distribution asymmetry may be an interesting observable either to be helpful in searching for the signal of the charged Higgs boson or to impose the significant bound on it.