Direct CP violation in hadronic τ decays

Abstract

The direct CP violation of τ decays τ ± → K ± P ν τ ( ν ¯ τ ) P = π 0 , η , η ′ is studied. We have computed CP violation in the forward-backward asymmetry. To predict CP violation, we use a chiral Lagrangian including vector and scalar mesons and take into account η and η ′ mixing. As for new physics with a new source of CP violation, we study the two-Higgs-doublet model with non-minimal structure of Yukawa coupling. Within the standard model and the form factors derived with the chiral Lagrangian, we have predicted various distributions of the decays, the forward and backward asymmetries, and the branching fraction of τ → ν τ K η ′ . With a two-Higgs-doublet model, CP violation in the forward-backward asymmetry is predicted.