Minimal model of gravitino dark matter

Abstract

Motivated by the absence of signals of new physics in searches for both new particles at the LHC and a weakly interacting massive particle dark matter candidate, we consider a scenario where supersymmetry is broken at a scale above the reheating temperature. The low-energy particle content then only consists of Standard Model states and a gravitino. We investigate the possibility that the latter provides the main component of dark matter through the annihilation of thermalized Standard Model particles. We focus on the case where its production through scattering in the thermal plasma is well approximated by the nonlinear supersymmetric effective Lagrangian of the associated Goldstino and identify the parameter space allowed by the cosmological constraints, allowing the possibility of a large reheating temperature compatible with leptogenesis scenarios and alleviating the so-called "gravitino problem".

The inflaton portal to dark matter

“…As is depicted in figure 3 the value predicted by our scenario is of order T R ∼ 10 10 GeV m φ , thus in agreement with the assumptions used while discussing non thermal production. As indicated in introduction, if sufficiently high regarding thermal leptogenesis [51], note that in the context of supersymmetric set up, such value of the reheating temperature may be in tension with other existing bounds [44,[52][53][54][55][56][57][58][59][60][61][62][63][64][65][66].…”

Gravitino decay in high scale supersymmetry with R -parity violation

“…7 To be more precise, above the maximum temperature of the thermal bath T max which is different from T RH if one considers noninstantaneous reheating [31]. rate is doubly Planck suppressed, the abundance of dark matter produced from the bath is very limited [proportional to T 7 RH [8] as in Eq. (2)], requiring a massive gravitino to compensate its low density.…”

“…Indeed, the only way to produce the gravitino in the early Universe if the supersymmetrybreaking scale lies above the reheating temperature, 7 T RH , is through the exchange of highly virtual sparticles with Planck-suppressed couplings, such as t-channel processes of the type GG →G → ψ μ ψ μ , with G,G representing the gluon and gluino, respectively [8]. Because the production FIG.…”

“…In high-scale supersymmetry models with the gravitino as the only superpartner lighter than the inflaton, gravitinos can be pair produced during reheating [7,8]. The gravitino production rate density was derived in Ref.…”

“…The exception may be the gravitino with an approximately EeV mass [7]. In this case, we still have a viable supersymmetric dark matter candidate, namely the gravitino which is produced from the thermal bath during reheating [7][8][9]. Interestingly, in the context of an SO(10) GUT, such highscale supersymmetric models are still able to account for gauge coupling unification, radiative electroweak symmetry breaking and the stability of the Higgs vacuum [10].…”