$R_{K^{(\ast )}}^{\nu }$ and non-standard neutrino interactions

Abstract

We discuss the modes $B\to K^{(\ast )}\nu \bar{\nu }$ in the context of non-standard neutrino interactions that add incoherently to the SM rates. We consider two scenarios: an additional light neutrino; and neutrino lepton flavour violation. We find that an additional light neutrino that interacts with SM fields via a non-universal $Z^{\prime }$ can increase $R_{K^{(\ast )}}^{\nu }$ by up to a factor of two without conflicting with $B_s-{\bar{B}}_s$ mixing. This model then predicts rates for $B_s\to {\tau }^{+}{\tau }^{-}$ up to six times larger than the SM. In the context of neutrino lepton flavour violation mediated by leptoquarks we find that the current experimental upper bounds on $R_{K^{(\ast )}}^{\nu }$ are already more constraining than direct bounds from $B_s\to \tau \ell$ and $B\to K^{(\ast )}\tau \ell$ modes for $\ell =e,\mu$.

Comments: fixed typo in Eqs. 7,8