Probing the muon gμ − 2 anomaly, Lμ − Lτ gauge boson and Dark Matter in dark photon experiments

In the Lμ−Lτ model the 3.6 σ discrepancy between the predicted and measured values of the anomalous magnetic moment of positive muons can be explained by the existence of a new dark boson Z′ with a mass in the sub-GeV range, which is coupled at tree level predominantly to the second and third lepton generations. However, at the one-loop level the Z′ coupling to electrons or quarks can be induced via the γ−Z′ kinetic mixing, which is generated through the loop involving the muon and tau lepton. This loophole has important experimental consequences since it opens up new possibilities for the complementary searches of the Z′ with high-energy electron beams, in particular in the ongoing NA64 and incoming dark photon experiments. An extension of the model able to explain relic Dark Matter density is also discussed.