This paper is a natural continuation of our paper Quantum Scalar Field in FRW Universe with Constant Electromagnetic Background, Int. J. Mod. Phys.A12, 4837 (1997). We generalize our previous work to the case of a massive spinor field, which is placed in a FRW universe of a special type with a constant electromagnetic field. So as to achieve this, special sets of exact solutions of the Dirac equation in the background under consideration are constructed and classified. Using these solutions representations for out–in, in–in, and out–out spinor Green functions are explicitly constructed as proper-time integrals over the corresponding contours in the complex proper-time plane. The vacuum-to-vacuum transition amplitude and the number of created particles are found and vacuum instability is discussed. The mean values of the current and of the energy–momentum tensor are evaluated, and different approximations for them are presented. The back reaction related to particle creation and to unstable vacuum polarization is estimated in different regimes.
Nonequilibrium inflaton dynamics and reheating: Back reaction of parametric particle creation and curved spacetime effects