Constraints on \alpha-attractor inflation and reheating

TL;DR

This paper derives constraints on reheating parameters and the alpha parameter in alpha-attractor inflation models, based on spectral index observations and different reheating scenarios, including perturbative decay and broad resonance.

Contribution

It provides new bounds on reheating e-folds, temperature, and the alpha parameter for E-model and T-model alpha-attractor inflation, considering various reheating phases and mechanisms.

Findings

Lower bound on inflaton decay coupling constant.

Constraint on alpha parameter, alpha > 0.01, for broad resonance reheating.

Bounds on reheating e-folds and temperature depending on the equation-of-state parameter.

Abstract

We investigate a constraint on reheating followed by alpha-attractor-type inflation (the E-model and T-model) from an observation of the spectral index n_s. When the energy density of the universe is dominated by an energy component with the cosmic equation-of-state parameter w_{re} during reheating, its e-folding number N_{re} and the reheating temperature T_{re} are bounded depending on w_{re}. When the reheating epoch consists of two phases, where the energy density of the universe is dominated by uniform inflaton field oscillations in the first phase and by relativistic non-thermalised particles in the second phase, we find a constraint on the e-folding number of the first oscillation phase, N_{sc}, depending the parameters of the inflaton potential. For the simplest perturbative reheating scenario, we find the lower bound for a coupling constant of inflaton decay in the E-model and T-model depending on the model parameters. We also find a constraint on the $\alpha$ parameter, \alpha\simgt 0.01, for the T-model and E-model when we assume a broad resonance reheating scenario.