A re-analysis of gravitino dark matter in the constrained MSSM

We re-consider the gravitino as dark matter in the framework of the Constrained MSSM. We include several recently suggested improvements on: (i) the thermal production of gravitinos, (ii) the calculation of the hadronic spectrum from NLSP decay and (iii) the BBN calculation including stau bound-state effects. In most cases we find an upper bound on the reheating temperature TR ≲ a few × 107GeV from over-production of 6Li from bound state effects. We also find an upper limit on the stau lifetime of 3 × 104sec, which is nearly an order of magnitude larger than the simple limit 5 × 103sec often used to avoid the effect of bound-state catalysis. The bound on TR is relaxed to ≲ a few × 108GeV when we use a more conservative bound on 6Li/7Li, in which case a new region at small stau mass at ∼ 100GeV and much longer lifetimes opens up. Such a low stau mass region can be easily tested at the LHC. © 2009 Chin. Phys. Soc. and IOP Publishing Ltd.