Thermal and Non-Thermal Production of Gravitinos in the Early Universe

We present a full one-loop calculation of the gravitino thermal production rate, beyond the so-called hard thermal loop approximation, using the corresponding thermal spectral functions in numerical form on both sides of the light cone. This framework requires a full numerical evaluation. We interpret our results within the framework of a general supergravity-based model, remaining agnostic about the specifics of supersymmetry breaking. In this context, assuming that gravitin...

Gravitino production and decay in the inflationary universe are reexamined. Assuming that the gravitino mainly decays into a photon and a photino, we calculate the upperbound on the reheating temperature. Compared to previous works, we have essentially improved the following two points: (i) the helicity $\pm\frac{3}{2}$ gravitino production cross sections are calculated by using the full relevant terms in the supergravity lagrangian, and (ii) the high energy photon spectrum i...

We study the production of gravitinos during the preheating era after inflation by means of the non-perturbative Bogolyubov technique. Considering only the helicity $\pm 3/2$ states, the problem is reduced to the simpler Dirac fermions case. We calculate the production in a particular supergravity model in an expanding universe and obtain the spectrum and number density. Finally we compare the results with the nucleosynthesis bounds and extract some consequences.

We discuss gravitino production from reheating in models where the splitting between particle and sparticle masses can be larger than TeV, as naturally arising in the context of split supersymmetry. We show that such a production typically dominates over thermal contributions arising from the interactions of gauginos, squarks and sleptons. We constrain the supersymmetry breaking scale of the relevant sector for a given reheat temperature. However the situation changes when th...

We revisit the nonthermal gravitino production at the (p)reheating stage after inflation. Particular attention is paid to large field inflation models with a $\mathbb{Z}_2$ symmetry, for which the previous perturbative analysis is inapplicable; and inflation models with a stabilizer superfield, which have not been studied non-perturbatively. It is found that in single-superfield inflation models (without the stabilizer field), nonthermal production of the transverse gravitino...

We estimate the production of gravitinos during and after the end of a period of warm inflation, a model in which radiation is produced continuously as the field rolls down the potential producing dissipation. We find that gravitino production is efficient for models in the strong dissipation regime, with the result that standard nucleosynthesis is disrupted unless the magnitude of the inflaton potential is very small. Combining this with the constraint from the thermal produ...

Gravitino problem is discussed in detail. We derive an upperbound on the reheating temperature from the constraints of the big-bang nucleosynthesis and the present mass density of the universe. Compared to previous works, we have improve the following three points; (i) the gravitino production cross sections are calculated by taking all the relevant terms in the supergravity lagrangian into account, (ii) high energy photon spectrum is obtained by solving the Boltzmann equatio...

We obtain new stronger bounds by orders of magnitude, on the ultimate temperature of the universe by exploiting the copious production of gravitinos at finite temperature.

By using a No-Scale Supergravity model, which was proved to explain WMAP observations appropriately, a mechanism of supersymmetry breaking and a preheating just after the end of inflation are investigated. Non-thermal production rate of gravitino is estimated as well as supersymmetry breaking mechanism numerically. The supersymmetry breaking is triggered by the inflaton superfield alone and the interchange of supersymmetry breaking fields does not occur in our model. By the i...

Gravitino production and decay in the inflationary universe are reexanimed. Assuming that gravitino mainly decays into photon and photino, we have calculated the upperbound of the reheating temperature. Compared to previous works, we have essentially improved the following two points; (i) the helicity $\pm\frac{3}{2}$ gravitino production cross sections are calculated by using the full relevant terms in the supergravity lagrangian, and (ii) high energy photon spectrum is obta...