Exclusive hadronic τ decays in the resonance effective action of QCD

Abstract

Until present the study of the form factors associated to the vector and axial-vector components of the hadronic weak current has been carried out with a plethora of modelizations of the underlying strong interactions. While of importance to get an understanding of the dynamics involved, the amount and quality of the experimental data start to show some discrepancies with the analysed models. Moreover, and from a theoretical point of view, most of these models are not consistent with quantum chromodynamics (QCD). We propose a QCD-based model-independent procedure to analyse those decays through the use of the resonance chiral theory, the low-energy effective action of QCD in the relevant resonance region. Within this framework we study the hadronic off-shell width of the ϱ meson and the vector form factor of pion in τ − → π −π 0ν τ. We also comment on the τ − → (πππ) −ν τ decay.