Thermal inflation and the moduli problem

Abstract

In supersymmetric theories a field can develop a vacuum expectation value M\ensuremath{\gg}${10}^{3}$ GeV, even though its mass m is of order ${10}^{2}$ to ${10}^{3}$ GeV. The finite temperature in the early Universe can hold such a field at zero, corresponding to a false vacuum with an energy density ${\mathit{V}}_{0}$\ensuremath{\sim}${\mathit{m}}^{2}$${\mathit{M}}^{2}$. When the temperature falls below ${\mathit{V}}_{0}^{1/4}$, 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 or moduli problem if M is within one or two orders of magnitude of ${10}^{12}$ GeV. Parametric resonance may lead to rapid partial reheating giving a high enough temperature for a variety of methods of baryogenesis. One can also have double thermal inflation which can solve the Polonyi or moduli problem even more efficiently. \textcopyright{} 1996 The American Physical Society.