On the thermal regeneration rate for light gravitinos in the early Universe

• Published in: Astroparticle physics Vol. 4; no. 4; pp. 371 - 385
• Main Authors: Ellis, John, Nanopoulos, D.V., Olive, Keith A., Rey, Soo-Jong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.1996
• ISSN: 0927-6505; 1873-2852
• DOI: 10.1016/0927-6505(96)00006-0

We investigate the light gravitino regeneration rate in the early Universe in models based on N = 1 supergravity. Motivated by a recent claim by Fischler, we evaluate finite-temperature effects on the gravitino regeneration rate due to the hot primordial plasma for a wide range of the supersymmetry-breaking scale F. We find that the leading thermal corrections to the gravitino pole mass and to the Goldstino coupling are negligible for a wide range of temperatures, thereby justifying the extension of the equivalence theorem for the helicity-1/2 gravitino and Goldstino to a hot primordial plasma background. Utilizing the Braaten-Pisarski resummation method, and assuming that the other particles are close to thermal equilibrium, the helicity-1/2 gravitino regeneration rate is found to be insensitive to magnetic Debye screening and of order α s(T) log(1/α s(T))¦m soft/ F ¦ 2T 3(1α s(T) log(1/α s(T))T 2/¦F ¦) up to a calculable, model-dependent O(1) numerical factor. We review the implications of this regeneration rate for supergravity cosmology, focusing in particular on scenarios for baryogenesis.