Quantum effects in the early Universe. IV. Nonlocal effects in particle production in anisotropic models

The dynamical equation governing the evolution of the effective geometry in the presence of the production of conformally invariant scalar particles is solved for a homogeneous model cosmology with small anisotropy and classical radiation. The pair-production probabilities and spectrum are calculated in the one-loop approximation to lowest nonvanishing order in the deviation from exact isotropy.