Constraining U(1) L μ – L τ 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 σ discrepancy compared with the expectation of the Standard Model 1. A new light gauge boson X in the L μ – L τ model provides a good explanation for the g – 2 anomaly. A Dirac fermion dark matter with a large L μ – L τ charge can explain both the g – 2 anomaly and the dark matter relic density 2. 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 Ψ > m μ ) for which the channel ΨΨ ⟶ μ - μ + opens. Although the cross section ( σ v ) μ - μ + is smaller by a factor of 1/ q Ψ 2 ( q Ψ represents the L μ – L τ charge of the dark matter) compared with the channel ΨΨ ⟶ X X ⟶ ννν̅ν̅ , 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 ΨΨ ⟶ μ - μ + , which rules out part of the parameter space of the large L μ – L τ charged dark matter model to account for the muon g – 2 anomaly.