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On the thermal regeneration rate for light gravitinos in the early Universe |
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| Authors: | John Ellis D.V. Nanopoulos Keith A. Olive Soo-Jong Rey |
| Affiliation: | aTheory Division, CERN, CH-1211 Geneva, Switzerland bDepartment of Physics, Texas A&M University, College Station, TX 77843, USA cAstroparticle Physics Group, Houston Advanced Research Center (HARC), The Mitchell Campus, The Woodlands, TX 77381, USA dDepartment of Physics, University of Minnesota, Minneapolis, MN 55455, USA ePhysics Department and Center for Theoretical Physics, Seoul National University, Seoul 151-742, South Korea |
| Abstract: | 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 s(T) log(1/s(T))¦msoft/ F ¦2T3(1s(T) log(1/s(T))T2/¦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. |
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