Scalar dark matter interpretation of the DAMPE data with U(1) gauge interactions

Abstract

Recently, DAMPE experiment released the new measurement of the total cosmic $e^{+}{e}^{-}$ flux between 25 GeV and 4.6 TeV which indicates a spectral softening at around 0.9 TeV and a tentative peak at around 1.4 TeV. We utilize the scalar dark matter (DM) annihilation scenario to explain the DAMPE peak by extending $G_{SM}\equiv SU(3{)}_C\times SU(2{)}_L\times U(1{)}_Y$ with additional $U(1)$ gauge symmetries while keeping anomaly free to generate $\chi \chi \to Z^{\prime }{Z}^{\prime }\to \ell \bar{\ell }{\ell }^{\prime }\overline{{\ell }^{\prime }}$, where $\chi ,Z^{\prime },{\ell }^{{(}^{\prime })}$ denote the scalar DM, the new gauge boson and ${\ell }^{{(}^{\prime })}=e,\mu ,\tau$, respectively, with $m_{\chi }\sim m_{Z^{\prime }}\sim 2\times 1.5$ (TeV). We first illustrate that the minimal framework $G_{SM}\times U(1{)}_{Y^{\prime }}$ with the above mass choices can explain the DAMPE excess but has been excluded by LHC constraints from the $Z^{\prime }$ searches. Then we study a non-minimal framework $G_{SM}\times U(1{)}_{Y^{\prime }}\times U(1{)}_{Y^{\prime \prime }}$ in which $U(1{)}_{Y^{\prime \prime }}$ mixes with $U(1{)}_{Y^{\prime }}$. We show that such a framework can interpret the DAMPE data while passing other constraints including the DM relic abundance, DM direct detection and collider bounds. We also investigate the predicted $e^{+}{e}^{-}$ spectrum in this framework and find that the mass splitting $\Delta m=m_{\chi }-m_{Z^{\prime }}$ should be less than about 17 GeV to produce the peak-like structure.

Comments: 15 pages, 6 figures, 3 tables