Classical decay of inflaton

Abstract

We present the first fully non-linear calculation of inflaton decay. We map inflaton decay onto an equivalent classical problem and solve the latter numerically. In the $\lambda {\varphi }^4$ model, we find that parametric resonance develops slower and ends at smaller values of fluctuating fields, as compared to estimates existing in literature. We also observe a number of qualitatively new phenomena, including a stage of semiclassical thermalization, during which the decay of inflaton is essentially as effective as during the resonance stage.

Comments: 10 pages, 3 figures, LaTeX. A misprint in the in-line formula after eq.(6) is corrected; the remark on renormalization is improved; factor 1/24 in the definition of $T_{\mathrm{eff}}$ is replaced by the correct 1/12