Secluded WIMPs, QED with massive photons, and the galactic center gamma-ray excess

Understand

We propose to investigate a secluded WIMP dark matter model consisting of neutral fermions as the dark matter candidate and a Proca-Wentzel (PW) field as a mediator.

• In the model that we consider here, dark matter WIMPs interact with standard model (SM) particles only through the PW field of ~ MeV -- multi-GeV mass particles.
• The interactions occur via an U(1)' mediator, V_{\mu}', which couples to the SM by kinetic mixing with U(1) hypercharge bosons, B_{\mu}.
• One important difference between our model and other such models in the literature is the absence of an extra singlet scalar, so that the parameter with dimension of mass M^2_V is not related to a spontaneous symmetry breaking.