Light vector dark matter with scalar mediator and muon g-2 anomaly

We study a model with a vector dark matter (DM) candidate interacting with the standard model (SM) charged leptons through a scalar portal. The dark matter candidate acquires mass when the complex scalar breaks an Abelian gauge symmetry spontaneously. The scalar interacts with the SM charged leptons through a dimension-6 operator. The scalar mediator induces elastic scattering of dark matter with electrons at tree level and also DM-nucleon interaction when the effects from scalar-Higgs mixing are taken into account. Given the recent results from Xenon1T upper bounds on DM-electron elastic scattering cross sections where the strongest sensitivity lies in the range similar to O(1) GeV, we find the viable space in the parameter space respecting constraints from the observed relic density, direct detection, muon (g(mu) - 2) anomaly, e(+)e(-) colliders, electron beam-dump experiments and astrophysical observables. It is shown that the current upper bounds of Xenon1T on DM-electron interactions are partially sensitive to the regions in the viable parameter space which is already excluded by the electron beam-dump experiment, Orsay. We also find that there are viable DM particles with masses similar to O(1) GeV evading the direct detection but standing well above the neutrino floor. Almost the same viable regions are found when we apply the direct detection upper limits on the DM-proton spin-independent cross section.

Automated summary

A model with vector dark matter interacting with standard model charged leptons through a scalar portal is studied, determining viable parameter space respecting various constraints. Results show partial sensitivity of Xenon1T upper bounds on DM-electron interactions to regions already excluded by the Orsay electron beam-dump experiment, and viable dark matter particles with masses around O(1) GeV evading direct detection are identified.