Dirac Fermionic Dark Matter Confronting the Latest Data

It is well known that the Dirac fermionic dark matter (DM) is seriously constrained by the spin-independent (SI) experiments of DM-nucleus elastic scattering. To evade the vector interaction of DM with the $Z$ boson, we take the quantum numbers of the Dirac DM to be $I\neq 0, I_3=Y=0$. The effective couplings from loop contribution should be considered. We find that there is a cancellation in one-loop diagrams, which largely reduces the cross section and makes the Dirac DM viable in the direct search. Besides, for a generic isospin $I$, we survey the Dirac DM mass constrained by the recent results of PandaX-II, XENON1T and LUX experiments in the direct search, the observed DM relic density, and the H.E.S.S and Fermi-LAT astrophysical observations in the indirect search. With the Sommerfeld enhancement effect, we find that the H.E.S.S. data and the observed DM relic density become serious constraints on the DM mass. The $I=1$ case is ruled out and Dirac DM masses are forced to be within the ranges of a few to few tens TeV for $2 \leqslant I \leqslant 4$ and few tens to few hundreds TeV for $I \geqslant 5$.}