Prospects of $Z^{\prime }$ Portal Dark Matter in $U(1{)}_{L_{\mu }-L_{\tau }}$

Abstract

The gauged $U(1{)}_{L_{\mu }-L_{\tau }}$ model is well-motivated to explain the muon $g-2$ anomaly and dark matter in previous studies. However, the latest NA64$\mu$ experiment has almost excluded all the parameter space for the muon $g-2$, which indicates that the light dark matter benchmark scenarios interpreting muon $g-2$ in previous studies are also not allowed at present. In light of many recent and future experimental results, we revisit the minimal $Z^{\prime }$ portal dark matter in $U(1{)}_{L_{\mu }-L_{\tau }}$. Focus on the phenomenology of dark matter $\chi$, we first explore the viable parameter space for the light dark matter under various tight constraints. Around the $Z^{\prime }$ resonance, we find that there is still a large parameter space for $m_{\chi }\gtrsim 10$ MeV via thermal freeze-out. On the other hand, the constraints on $Z^{\prime }$ above the electroweak scale are quite loose but are less studied for dark matter. We also investigate the heavy dark matter around the TeV scale and corresponding constraints. A large part of the parameter space for dark matter is within the reach of future experiments.

Comments: 17 pages, 7 figures