Polarization effects in radiative decay of polarized $τ$ lepton

Abstract

The polarization effects in the one-meson radiative decay of the polarized $τ$ lepton, $τ^-\toπ^-γν_τ$, are investigated. The inner bremsstrahlung and structural amplitudes are taken into account. The asymmetry of the differential decay width caused by the $τ$ lepton polarization and the Stokes parameters of the emitted photon itself, are calculated depending on the polarization of the decaying $τ$ lepton. The numerical estimation of these physical quantities was done for arbitrary direction of the $τ$ lepton polarization 3-vector in the rest frame. The vector and axial-vector form factors describing the structure-dependent part of the decay amplitude are determined using the chiral effective theory with resonances (R$χ$T).