Calculations of Inflaton Decays and Reheating: with Applications to No-Scale Inflation Models

Abstract

We discuss inflaton decays and reheating in no-scale Starobinsky-like models of inflation, calculating the effective equation-of-state parameter, $w$, during the epoch of inflaton decay, the reheating temperature, $T_{\mathrm{reh}}$, and the number of inflationary e-folds, $N_{\ast }$, comparing analytical approximations with numerical calculations. We then illustrate these results with applications to models based on no-scale supergravity and motivated by generic string compactifications, including scenarios where the inflaton is identified as an untwisted-sector matter field with direct Yukawa couplings to MSSM fields, and where the inflaton decays via gravitational-strength interactions. Finally, we use our results to discuss the constraints on these models imposed by present measurements of the scalar spectral index $n_s$ and the tensor-to-scalar perturbation ratio $r$, converting them into constraints on $N_{\ast }$, the inflaton decay rate and other parameters of specific no-scale inflationary models.

Comments: 33 pages, 14 figures