Enhancement of Line Gamma Ray Signature from Bino-like Dark Matter Annihilation due to CP Violation

Abstract

We study the line gamma ray signature from the Galactic Center originating from Bino-like dark matter pair annihilation, when CP is not conserved. We consider the case that the Bino is nearly degenerate with a sfermion in mass. Although an indirect detection of Bino-like dark matter is difficult in general, the signal of Bino-like dark matter pair annihialtion in this case is enormously enhanced due to the threshold singularity.

Comments: 4 pages, 5 eps files; comments added, Fig. 2,3 improved to see clearly