2007/03/12 by Maxim Pospelov, Adam Ritz · 6 citations
Physics and Astronomy · #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Particle physics theoretical and experimental studies #astro-ph #hep-ph
paper · pdf · doi:10.1016/j.physletb.2007.06.027
16 pages, 3 figures
arxiv created 2007/03/12 · openalex publication_date 2007/06/22 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We consider possible mechanisms via which electroweak scale WIMPs χ0 could provide the source of the INTEGRAL/SPI 511 keV photon flux from the galactic centre. We consider scenarios where the WIMP spectrum contains near-degeneracies, with MeV-scale splitting, and focus on three possible production mechanisms for galactic positrons: (i) collisional excitation of the WIMP to a nearby charged state, χ0 + χ0 -> χ+ + χ-, with the subsequent decay producing positrons; (ii) capture of the WIMP by nuclei in the galactic interstellar medium, χ0 + N -> e+ + (χ- N); and (iii) the decay of a nearby long-lived state surviving from the Big Bang, χ02 -> χ10 + e+ + e-. We find that process (i) requires a cross-section which is significantly larger than the unitarity bound, process (ii) is allowed by unitarity, but is impractical due to terrestrial bounds on the χ-N cross-section, while process (iii) is viable and we construct a simple model realization with singlet dark matter fields interacting with the Standard Model via the Higgs sector.