Thermal Inflation and the Moduli Problem

TL;DR

This work analyzes how flaton fields with large vevs and flat potentials can trigger a low-energy epoch of thermal inflation that dilutes the Polonyi/moduli problem without perturbing the density perturbations from ordinary inflation. By examining the flaton’s effective potential, decay rates, and finite-temperature dynamics, the authors show that a single thermal inflation episode with $M \sim 10^{12}$ GeV yields about 10 $e$-folds and sufficient entropy production to suppress preexisting moduli, while maintaining a viable reheat temperature. They further explore a double thermal inflation scenario, demonstrating that two successive inflations relax constraints further and can accommodate a broader range of $M$, including very large vevs. The results highlight the mechanism’s potential to reconcile supersymmetric cosmology with standard nucleosynthesis and dark matter constraints, though they leave room for future work on axions and baryogenesis within this framework.

Abstract

In supersymmetric theories a field can develop a vacuum expectation value $M \gg 10^3\,{\rm GeV}$, even though its mass $m$ is of order $10^2$ to $10^3\,{\rm GeV}$. The finite temperature in the early Universe can hold such a field at zero, corresponding to a false vacuum with energy density $ V_0 \sim m^2 M^2 $. When the temperature falls below $V_0^{1/4}$, the thermal energy density becomes negligible and an era of thermal inflation begins. It ends when the field rolls away from zero at a temperature of order $m$, corresponding to of order 10 $e$-folds of inflation which does not affect the density perturbation generated during ordinary inflation. Thermal inflation can solve the Polonyi/moduli problem if $M$ is within one or two orders of magnitude of $10^{12}\,{\rm GeV}$.