Resonance Chiral Lagrangian analysis of τ<SUP>-</SUP>→η<SUP>(′)</SUP>π<SUP>-</SUP>π<SUP>0</SUP>ν<SUB>τ</SUB>

Abstract

The hadronization structure of τ<SUP>-</SUP>→η<SUP>(′)</SUP>π<SUP>-</SUP>π<SUP>0</SUP>ν<SUB>τ</SUB> decays is analyzed using chiral perturbation theory with resonances, considering only the contribution of the lightest meson resonances at leading order in the 1/N C expansion. After imposing the asymptotic behavior of vector spectral functions ruled by QCD, unknown effective couplings are determined by fitting the τ<SUP>-</SUP>→η<SUP>(′)</SUP>π<SUP>-</SUP>π<SUP>0</SUP>ν<SUB>τ</SUB> branching ratio and decay spectrum to recent data. Predictions for the partner decay τ<SUP>-</SUP>→η<SUP>(′)</SUP>π<SUP>-</SUP>π<SUP>0</SUP>ν<SUB>τ</SUB> and the low-energy behavior of the cross section σ(e+e -→ηπ +π -) are also discussed.