Second-class current effects from isospin breaking in tau-->omega pi nu_tau

TL;DR

This paper investigates second-class current effects in tau decay to omega pi nu_tau, exploring isospin breaking contributions within a vector and axial-vector dominance framework, including omega-rho mixing and b_1(1235) mediation.

Contribution

It provides an estimate of second-class current effects in tau decay using a combined vector and axial-vector dominance model with omega-rho mixing.

Findings

Small axial vector contributions estimated

Omega-rho mixing effects analyzed

Potential b_1(1235) mediated amplitude discussed

Abstract

Second-class weak currents can in the standard model be induced by chiral symmetry breaking. In the specific case of the decay tau-->omega pi nu_tau, dominated by the first-class vector current with the rho quantum numbers, such effects would manifest themselves by small axial vector (or, generally, non-vector) contributions to the decay rate. We present an attempt to estimate such effects, based on a vector and axial-vector dominance model of the relevant matrix elements supplemented by omega-rho mixing. We also give an indication on the amplitude directly mediated by b_1(1235)-->omega pi, in principle also allowed in the standard model by isotopic spin violation.