Resolving $R_D$ and $R_{D^{\ast }}$ Anomalies in Adjoint SU(5)

Abstract

We investigate the $R_D$ and $R_{D^{\ast }}$ anomalies in the context of non-minimal $SU(5)$, where Higgs sector is extended by adjoint 45-dimensional multiplet. One of the light spectrum of this model could be the scalar triplet leptoquark that is contained in this multiplet. We demonstrate that this particular scalar leptoquark mediation of the transition $b\to c\tau \nu$ is capable of simultaneously accounting for both $R_D$ and $R_{D^{\ast }}$ anomalies. We further emphasize that another Yukawa coupling controls its contribution to $b\to s{\ell }^{+}{\ell }^{-}$, ensuring that $R_K$ and $R_{K^{\ast }}$ remain consistent with the standard model predictions.