${\tau }^{-}\to {\ell }_i^{-}{\ell }_i^{+}{\ell }_j^{-}{\bar{\nu }}_j{\nu }_{\tau }$ decays with a magnetic dipole term

Abstract

Using the massive helicity formalism we calculate the five-body average square amplitude of the decays ${\tau }^{-}\to {\ell }_i^{-}{\ell }_i^{+}{\ell }_j^{-}{\bar{\nu }}_j{\nu }_{\tau }$ $(\ell =e,\mu )$ within the Standard Model (SM), we then introduce a dimension-five effective vertex ${\Gamma }^{\tau \tau \gamma }$ in order to determine the feasibility of imposing limits on the tau anomalous magnetic dipole moment ($a_{\tau }$) via the current or future experimental measurements of the branching ratio for the decay ${\tau }^{-}\to e^{-}{e}^{+}{e}^{-}{\bar{\nu }}_e{\nu }_{\tau }$.

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