Constraining $U(1)_{L_{\mu}-L_{\tau}}$ charged dark matter model for muon $g-2$ anomaly with AMS-02 electron and positron data

Abstract

Very recently, the Fermi-Lab reported the new experimental combined results on the magnetic momentum of muon with a 4.2$\sigma$ discrepancy compared with the expectation of the Standard Model \cite{Fermi_Lab}. A new light gauge boson $X$ in the $L_{\mu}-L_{\tau}$ model provides a good explanation for the $g-2$ anomaly. A Dirac fermion dark matter with a large $L_{\mu}-L_{\tau}$ charge can explain both the $g-2$ anomaly and the dark matter relic density \cite{Asai_2021}. In this work, we focus on the case that the mass of the dark matter is larger than the mass of muon (i.e. $m_{\Psi} > m_{\mu}$) for which the channel $\Psi \Psi \rightarrow \mu^- \mu^+$ opens. Although the cross section $(\sigma v)_{\mu^{-}\mu^{+}}$ is smaller by a factor of $1/q_{\Psi}^2$ ($q_{\Psi}$ represents the $L_{\mu}-L_{\tau}$ charge of the dark matter) compared with the channel $\Psi\Psi \rightarrow XX \rightarrow \nu\nu\bar{\nu}\bar{\nu}$, the resulting secondary electrons and positrons could imprint on their spectra above GeV energies due to the reacceleration effect of cosmic ray propagation. We use the AMS-02 measurements of electrons and positrons to constrain the annihilation cross section of the channel $\Psi\Psi \rightarrow \mu^{-}\mu^{+}$, which rules out part of the parameter space of the large $L_{\mu}-L_{\tau}$ charged dark matter model to account for the muon $g-2$ anomaly.