Lattice study of classical inflaton decay

Abstract

We study numerically the decay of the inflaton by solving the full non-linear equations of motion on the lattice. We confirm that parametric resonance is effective in transferring energy from the inflaton to a scalar field as long as the self-interactions of the second field are very small. However, in the very broad resonance case (q>>1) the decay rate is limited by scatterings, which significantly slows down the decay. We also find that the inflaton cannot decay via parametric resonance into a scalar field with moderate self-interactions. This means that the preheating stage may be completely absent in many natural inflationary models.

Comments: 12 pages LaTeX with standard RevTex macros, uses epsf.sty. 7 postscript figures (included). No changes. Replaced to correct a problem with the figures