Gluino annihilations and neutralino dark matter

Abstract

We consider supersymmetric (SUSY) scenarios, compatible with all cosmological and phenomenological requirements, where the lightest SUSY particles (LSPs) are the neutralino and a quasidegenerate gluino. We study the neutralino relic abundance, focusing on gluino (co)annihilation effects. In case the neutralino is B-ino-like, in a wide mass window the relic abundance is naturally driven in the correct range for the LSP to be the main cold dark matter constituent. We show that the gluino is the strongest possible coannihilating partner of a B-ino-like neutralino in the general minimal supersymmetric standard model. Moreover, contrary to other coannihilation scenarios, gluino pair annihilations always dominate over coannihilation processes, even at relatively large gluino-neutralino mass splittings. Finally, we present prospects for neutralino dark matter detection in the outlined framework.