Inflation Dynamics and Reheating

TL;DR

This paper surveys inflation with both single- and multi-field dynamics, emphasizing adiabatic and entropy perturbations as primary tests of inflationary models. It develops a unified perturbation framework, connects primordial spectra to CMB observables, and discusses how reheating and preheating alter predictions, including non-Gaussianity and isocurvature signatures. The review extends to higher-dimensional scenarios, curvaton and modulated-reheating mechanisms, and highlights how upcoming data from Planck and large-scale structure surveys can discriminate between competing models. Overall, it underscores the rich phenomenology of multi-field inflation and the critical role of post-inflationary dynamics in shaping observable cosmology.

Abstract

We review the theory of inflation with single and multiple fields paying particular attention to the dynamics of adiabatic and entropy/isocurvature perturbations which provide the primary means of testing inflationary models. We review the theory and phenomenology of reheating and preheating after inflation providing a unified discussion of both the gravitational and nongravitational features of multi-field inflation. In addition we cover inflation in theories with extra dimensions and models such as the curvaton scenario and modulated reheating which provide alternative ways of generating large-scale density perturbations. Finally we discuss the interesting observational implications that can result from adiabatic-isocurvature correlations and non-Gaussianity.

Figures (16)

• Figure 1: Schematic illustration of the potential of large-field models.
• Figure 2: The schematic illustration of the potential of small-field models.
• Figure 3: Schematic illustration of the potential of hybrid (or double) inflation models given by Eq. (\ref{['hybridpo']}). Here $\phi_c$ is the critical value of the inflaton below which $\chi = 0$ becomes unstable due to tachyonic instability ($m_{\chi}^2 < 0$).
• Figure 4: Classification of inflationary models in the $n_{\cal R}$-$r$ plane in the low-energy limit. The line $r=(8/3)(1-n_{\cal R})$ marks the border of large-field and small-field models, whereas the border of large-field and hybrid models corresponds to $r=8(1-n_{\cal R})$.
• Figure 5: Theoretical prediction of large-field models together with the $1\sigma$ and $2\sigma$ observational contour bounds from first year WMAP data. Each case corresponds to (a) $n=2$ and (b) $n=4$ with e-foldings $N=45, 50, 55, 60$ (from top to bottom) showing how models with few e-foldings are under severe pressure from observations.