Signatures of pseudo-degenerate WIMP dark matter

摘要

WIMP models of cold dark matter which exhibit nearly degenerate excited states have a number of interesting signatures that may prove relevant for direct and indirect searches. Such near-degeneracies form a qualitatively distinct regime in the parameter space of many models which, generically due to the little hierarchy problem, now require efficient co-annihilation to ensure the correct relic density. This work discusses the relevance of such scenarios for explaining the observed galactic 511 keV line, and also the impact on direct terrestrial searches which may be complicated by recombination-type processes.