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 αs(T) log(1/αs(T))\msoft/F\2T3(1 + αs(T) log(1/αs(T)) + T2/\F\) up to a calculable, model-dependent script O sign(1) numerical factor. We review the implications of this regeneration rate for supergravity cosmology, focusing in particular on scenarios for baryogenesis.
Bibliographical noteFunding Information:
We thank Eric Braaten, Andrei Linde and Michael Shaposhnikov for many helpful discussions. SJR acknowledges hospitality of the Theory Group at CERN where this work was initiated. This work was supported in part by U.S. NSF-KOSEF Bilateral Grant( SJR) , KRF Nondirected Research Grant 8 1500-134 1 (SJR) , KRF International Collaboration Grant ‘94 (SJR), KOSEF Purpose-Oriented Grant 94-1400-04-01-3 and SRC Program (SIR) and Ministry of Education BSRI-94-2418 (SJR); DOE grant DE-FG05-91 -ER-40633DOE (DVN) ; DOE grant DE-FG02-94ER40823 (KAO) .