A Study of the Effects of Preheating

We review results of a numerical study of resonant inflaton decay in a wide range of realistic models and parameters. Wide enough parametric resonance can withstand the expansion of the Universe, though account for the expansion is very important for determining precisely how wide it should be. For example, the effective production of particles with mass ten times that of the inflaton requires very large values of the resonance parameter q, q > 10. For these large q, the maximal size of produced fluctuations is significantly suppressed by back reaction, 〈X〉 ∼ 10M Pl . We discuss some physical implications of our results.