CP violation in hadronic τ decays

Abstract

We consider CP-violating effects in τ→3πντ and 4πντ(ΔS=0), and τ→Kππντ(ΔS=1), assuming that the usual Standard Model amplitudes for these processes interfere with analogous amplitudes mediated by a charged Higgs boson. In the ΔS=0 case we focus specifically on the intermediate resonant processes τ→Vπντ (with V=ω,ρ, and a1), and consider three CP-odd observables – the partial rate asymmetry, a polarization-dependent asymmetry and a triple-product asymmetry. In the ΔS=1 case we examine the partial rate asymmetry, two “modified” rate asymmetries, and a triple-product asymmetry. The partial rate asymmetry is expected to be small for both the ΔS=0 and ΔS=1 cases. Evaluation of the other asymmetries indicates that they could potentially be measurable.