Study of an anomalous tau lepton decay using a chiral Lagrangian with vector mesons

Abstract

The hadronic tau decay $τ^- \to ν_τηπ^- π^0$ occurs through V-A weak current. In this decay mode, the vector current contribution is intrinsic parity violating and the axial current contribution is G parity violating. The latter contribution is suppressed due to tiny isospin breaking. We have computed both vector and axial vector form factors using a chiral Lagrangian with vector mesons including the effect of isospin breaking and intrinsic parity violation. A numerical result of the invariant mass distribution is shown and the structure of $ρ$ resonance can be seen in the distribution with respect to $M_{π^- π^0}$.