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

TL;DR

This paper analyzes inflaton decay and reheating in no-scale inflation models, providing analytical and numerical results that connect model parameters with observable cosmological constraints such as spectral index and tensor-to-scalar ratio.

Contribution

It offers a comprehensive calculation of reheating parameters in no-scale inflation models and applies these to constrain model parameters using current cosmological data.

Findings

Reheating temperature and e-folds are computed for various no-scale models.

Inflaton decay channels significantly affect reheating dynamics.

Current measurements constrain inflaton decay rates and model parameters.

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, $T_{\rm reh}$, and the number of inflationary e-folds, $N_*$, 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 $N_*$, the inflaton decay rate and other parameters of specific no-scale inflationary models.