Inflation and Reheating in Induced Gravity

TL;DR

This paper investigates inflation within induced gravity models, analyzing cosmological perturbations for different potentials, constraining model parameters with observational data, and exploring the decay of the inflaton during oscillations.

Contribution

It provides a detailed analysis of inflation and perturbations in induced gravity, constrains model parameters using WMAP data, and describes the decay process of the inflaton during oscillations.

Findings

Small field inflation models constrained by WMAP data to γ ≲ 3×10^{-3}

Cosmological perturbations analyzed for LG and CW potentials

Analytic approximation of inflaton decay during oscillations

Abstract

Inflation is studied in the context of induced gravity (IG) $\gamma \sigma^2 R$, where $R$ is the Ricci scalar, $\sigma$ a scalar field and $\gamma$ a dimensionless constant. We study in detail cosmological perturbations in IG and examine both a Landau-Ginzburg (LG) and a Coleman-Weinberg (CW) potential toy models for small field and large field (chaotic) inflation and find that small field inflationary models in IG are constrained to $\gamma \lesssim 3 \times 10^{-3}$ by WMAP 5 yrs data. Finally we describe the regime of coherent oscillations in induced gravity by an analytic approximation, showing how the homogeneous inflaton can decay in its short-scale fluctuations when it oscillates around a non-zero value $\sigma_0$.