Thermal leptogenesis and the gravitino problem in the Asaka-Yanagida axion/axino dark matter scenario

Understand

A successful implementation of thermal leptogenesis requires the re-heat temperature after inflation T_R to exceed ~2\times 10^9 GeV.

• Such a high T_R value typically leads to an overproduction of gravitinos in the early universe, which will cause conflicts, mainly with BBN constraints.
• Asaka and Yanagida (AY) have proposed that these two issues can be reconciled in the context of the Peccei-Quinn augmented MSSM (PQMSSM) if one adopts a mass hierarchy m(sparticle)>m(gravitino)>m(axino), with m(axino) keV.
• We calculate the relic abundance of mixed axion/axino dark matter in the AY scenario, and investigate under what conditions a value of T_R sufficient for thermal leptogenesis can be generated.