Gravitino dark matter in the constrained minimal supersymmetric standard model with improved constraints from big bang nucleosynthesis

Abstract

In the framework of the constrained MSSM we re-examine the gravitino as the lightest superpartner and a candidate for cold dark matter in the Universe. Unlike in most other recent studies, we include both a thermal contribution to its relic population from scatterings in the plasma and a non-thermal one from neutralino or stau decays after freeze-out. Relative to a previous analysis (Roszkowski et al 2005 J. High. Energy Phys. JHEP08(2005)080) we update, extend and considerably improve our treatment of constraints from observed light element abundances on additional energy released during BBN in association with late gravitino production. Assuming the gravitino mass in the GeV to TeV range, and for natural ranges of other supersymmetric parameters, the neutralino region is excluded, except for rather exceptional cases, while for smaller values of it becomes allowed again. The gravitino relic abundance is consistent with observational constraints on cold dark matter from BBN and CMB in some well defined domains of the stau region but, in most cases, only due to a dominant contribution of the thermal population. This implies, depending on , a large enough reheating temperature. If then TR > 108 GeV, if allowed by BBN and other constraints but, for light gravitinos, if then TR > 3 × 103 GeV. On the other hand, constraints mostly from BBN imply an upper bound , which is marginally consistent with thermal leptogenesis. Finally, most of the preferred stau region corresponds to the physical vacuum being a false vacuum. The scenario can be partially probed at the LHC.

Dark matter from gaugino mediation

“…However, it turns out that this is ruled out by the BBN constraints in gaugino mediation. The region where m χ > m 3/2 + m Z is certainly excluded by the hadronic BBN constraints for all gravitino masses we consider, since the two-body decay χ 0 1 → Z G is possible and since the hadronic branching ratio of the Z is large [10,27]. However, the situation is less clear for lighter neutralinos when the two-body decay into real Z bosons is not possible.…”

Probing the reheating temperature at colliders and with primordial nucleosynthesis

“…It is the region to the right of the respective line that is disfavored by 6 Li/H| CBBN exceeding the limit inferred from observations. Only the constraint from the primordial D abundance on hadronic energy release [4,6] in l 1 decays [20,21,22] can be more severe than the CBBN constraints [7,15,23,43,44,46]. 10 In Figs.…”

“…Assuming R-parity conservation, the gravitino LSP is stable and a promising candidate for dark matter; cf. [10,12,13,14,15,16,17,18,19,20,21,22,23] and references therein. Because of the extremely weak interactions of the gravitino, the NLSP typically has a long lifetime before it decays into the gravitino.…”

Gravitino dark matter and neutrino masses with bilinearR-parity violation

“…There have been several studies of gravitino dark matter in R-parity conserving supersymmetry [23][24][25][26]. In this case the lightest supersymmetric particle is stable and is potentially a viable dark matter candidate [23][24][25][26].…”

“…In this case the lightest supersymmetric particle is stable and is potentially a viable dark matter candidate [23][24][25][26]. Here we consider this issue within the simplest R-parity violating scenario.…”