Phenomenology of τ−→π−ντγ using light cone sum rules

We present the study of radiative tau decay ($\tau^- \rightarrow \pi^- \nu_\tau \gamma$), computing structure dependent contribution using Light Cone Sum Rules. This includes same form factors as pion with crucial difference that momentum transfer squared, $t$, between pion-photon system is positive, which makes these timelike and also $t$ can now take values upto $m_\tau^2$ , it produce real hadronic resonances. The analytical for has been calculated light cone sum rules method invariant mass-spectrum in $\pi-\gamma$ width are presented. parameter, $\gamma$, ratio axial to vector factor found be good agreement experimental determination.