Dark and Visible Photons as Source of CP Violation

The problem of excess gamma radiation in the center of galaxy is discussed assuming that the photon's production is dominated by two kinds of processes, the first one due to the conventional kinetic mixing term and, secondly, due to a kinetic mixing term violating the CP symmetry between dark and visible photons. The CP violation symmetry between dark and visible sectors is not forbidden and, in principle, could be considered as an additional source of CP violation. The conversion probability between dark and visible photons is calculated and compared between both processes. The processes violating CP are less significant but contribute non-trivially to the excess gamma radiation.