CP asymmetry in τ → Kπντ within non-minimal SU(5)

Abstract

Direct CP asymmetry in semi-leptonic τ decays is an intriguing hint for new physics beyond the standard model. We investigate the CP asymmetry in $$ {\tau}^{-}\to {K}_S^0{\pi}^{-}{\nu}_{\tau } $$ τ − → K S 0 π − ν τ and τ− → K−π0ντ decays in the context of the non-minimal SU(5) model, with 45-dimensional Higgs multiplet. We show that the associate color-triplet scalar, which is a natural example of a scalar leptoquark, can mediate the $$ \tau \to s\overline{u}{\nu}_{\tau } $$ τ → s u ¯ ν τ transition and account for the observed 2.8 σ discrepancy in $$ {A}_{\textrm{CP}}\left({\tau}^{-}\to {K}_S^0{\pi}^{-}{\nu}_{\tau}\right) $$ A CP τ − → K S 0 π − ν τ compared to the SM expectation. We also predict a sizable ACP(τ− → K−π0ντ), of $$ \mathcal{O} $$ O (10−3), which can be experimentally accessible in current and near future experiments.