Light dark matter, rare $B$ decays with missing energy in $L_{\mu }-L_{\tau }$ model with a scalar leptoquark

Abstract

We investigate the phenomenology of light GeV-scale fermionic dark matter in $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge extension of the Standard Model. Heavy neutral fermions alongside with a $S_1(\overline{3}$,$1$,$1/3$) scalar leptoquark and an inert scalar doublet are added to address the flavor anomalies and light neutrino mass respectively. The light gauge boson associated with $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge group mediates dark to visible sector and helps to obtain the correct relic density. Aided with a colored scalar, we constrain the new model parameters by using the branching ratios of various $b\to sll$ and $b\to s\gamma$ decay processes as well as the lepton flavour non-universality observables $R_{K^{(\ast )}}$ and then show the implication on the branching ratios of some rare semileptonic $B\to (K^{(\ast )},\varphi )+$ missing energy, processes.

Comments: 34 pages, 8 figures, version to appear in PRD