Thermal inflation and the moduli problem.

In supersymmetric theories a eld can develop a vacuum expectation value M 10GeV, even though its mass m is of order 10 to 10GeV. The nite temperature in the early Universe can hold such a eld at zero, corresponding to a false vacuum with energy density V0 m 2 M . When the temperature falls below V 1=4 0 , the thermal energy density becomes negligible and an era of thermal in ation begins. It ends when the eld rolls away from zero at a temperature of order m, corresponding to of order 10 e-folds of in ation which does not a ect the density perturbation generated during ordinary in ation. Thermal in ation can solve the Polonyi/moduli problem if M is within one or two orders of magnitude of 10GeV. 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 in ation which can solve the Polonyi/moduli problem even more e ciently. LANCASTER-TH/9505 hep-ph/9510204