Dark matter for b \u2192 s\u03bc+\u03bc\u2212 anomaly in a gauged U(1)X model

Abstract

We propose a new physics model which has a cold dark matter candidate and can explain the b → sμ+μ− anomaly at the same time. Our model includes a scalar quark tilde{q} and a scalar lepton tilde{ell} which are SU(2)L-doublet as well as a Dirac fermion N which is SU(2)L-singlet. The new particles are charged under a gauged U(1)X group which is spontaneously broken to a discrete Z2 symmetry by a dark scalar S. The remnant Z2 symmetry stabilizes the dark matter. Box diagrams with tilde{q} , tilde{ell} , and N running inside the loop can generate the correct Wilson coefficients C9μ = − C10μ to accommodate the b → sμ+μ− anomaly while avoiding constraints such as {B}_s-{overline{B}}_s mixing. The dark matter annihilation into a second generation lepton pair via t-channel tilde{ell} -exchanging process plays an important role in producing the current dark matter relic abundance of the universe, showing a strong interplay between the flavor and dark matter physics. We also discuss dark-gauge-interaction-dominated and Higgs-portal-dominated scenarios for dark matter physics.