Gravitino thermal production revisited and a new cosmological scenario of gauge mediation

Abstract

We present a new scenario of gravitino dark matter which is compatible with the thermal leptogenesis. We confirm by an explicit calculation in supergravity that the relic abundance of thermally produced gravitino becomes insensitive to the reheating temperature once the temperature of the Universe exceeds the mass scale of the messenger fields. In such a situation, the correct baryon to dark matter ratio can be obtained by thermal leptogenesis when the reheating temperature after inflation is high enough. We demonstrate in a concrete model of gauge mediation that the correct abundance of gravitino and baryon asymmetry can be reproduced by considering the late-time entropy production from the decay of the SUSY-breaking pseudo-moduli field. The scenario is realized when the gravitino mass is 100 MeV m 3/2

Suppressing gravitino thermal production with a temperature-dependent messenger coupling

“…In addition, scenarios such as the thermal leptogenesis, that requires high reheating temperatures, is hard to be reconciled with viable gravitino cosmology. R-parity violating vacua [23] or late entropy production [24,25] has to be invoked to address the tension. The constraints become much more severe when the messengers fields, the building blocks of the GMSB theories, are involved in the gravitino generation processes [26,27,28,29,25].…”

“…• For T > M mess the messengers become relativistic, are integrated in, and it has been shown that the gravitino production rate from the MSSM is suppressed by the factor M 2 mess /T 2 compared to the conventional rate one obtains for energies lower than the messenger mass scale [26,29,25].…”

“…These observations are not accounted into formula (1). Instead the formula should be corrected to [26,29,25]…”

Sgoldstino-less inflation and low energy SUSY breaking

“…2 There are models where the inflaton resides directly into the hidden sector [34][35][36][37][38][39], though there seem to be difficulties in getting towards low supersymmetry breaking scales.…”

“…The inflationary paradigm for the very early universe is indeed supported by more and more experimental evidence, and the high energy scales that it naturally involves beg for its embedding in supergravity, as a first step towards a more complete quantum treatment in string theory models. 1 Models where the sgoldstino itself is the inflaton exist [24][25][26][27], though it has been more popular to consider an inflaton superfield together with a stabilizer superfield [28], which can cure most of the problems of SUGRA inflation, and/or together with a supersymmetry breaking sector [29][30][31].2 There are models where the inflaton resides directly into the hidden sector [34][35][36][37][38][39], though there seem to be difficulties in getting towards low supersymmetry breaking scales.…”