Flavor-nonuniversal dark gauge bosons and the muon g−2

The possibility of explaining the current value of the muon anomalous magnetic moment in models with an additional U(1) gauge symmetry that has kinetic mixing with hypercharge are increasingly constrained by dark photon searches at electron accelerators. Here we present a scenario in which the couplings of new, light gauge bosons to standard model leptons are naturally weak and flavor nonuniversal. A vector-like state that mixes with standard model leptons serves as a portal between the dark and standard model sectors. The flavor symmetry of the model assures that the induced couplings of the new gauge sector to leptons of the first generation are very small and lepton-flavor-violating processes are adequately suppressed. The model provides a framework for constructing ultraviolet complete theories in which new, light gauge fields couple weakly and dominantly to leptons of the second or third generations.