tau -> pi pi pi nu_tau decays and the a_1(1260) off-shell width revisited

Abstract

The tau -> pi pi pi nu_tau decay is driven by the hadronization of the axial-vector current. Within the resonance chiral theory, and considering the large-Nc expansion, this process has been studied in Ref.[1]. In the light of later developments we revise here this previous work by including a new off-shell width for the lightest a_1 resonance that provides a good description of the tau -> pi pi pi nu_tau spectrum and branching ratio. We also consider the role of the rho(1450) resonance in these observables. Thus we bring in an overall description of the tau -> pi pi pi nu_tau process in excellent agreement with our present experimental knowledge.