Simplified TeV leptophilic dark matter in light of DAMPE data
  Using a simplified framework, we attempt to explain the recent DAMPE cosmic
$e^+ + e^-$ flux excess by leptophilic Dirac fermion dark matter (LDM). The
scalar ($\Phi_0$) and vector ($\Phi_1$) mediator fields connecting LDM and
Standard Model particles are discussed. Under constraints of DM relic density,
gamma-rays, cosmic-rays and Cosmic Microwave Background (CMB), we find that the
couplings $P \otimes S$, $P \otimes P$, $V \otimes A$ and $V \otimes V$ can
produce the right bump in $e^+ + e^-$ flux for a DM mass around 1.5 TeV with a
natural thermal annihilation cross-section $<\sigma v> \sim 3 \times 10^{-26}
cm^3/s$ today. Among them, $V \otimes V$ coupling is tightly constrained by
PandaX-II data (although LDM-nucleus scattering appears at one-loop level) and
the surviving samples appear in the resonant region, $m_{\Phi_1} \simeq
2m_{\chi}$. We also study the related collider signatures, such as dilepton
production $pp \to \Phi_1 \to \ell^+\ell^-$, and muon $g-2$ anomaly. Finally,
we present a possible $U(1)_X$ realization for such leptophilic dark matter.
