THERMAL INFLATION AND THE MODULI PROBLEM

In supersymmetric theories a field can develop a vacuum expectation va lue M much greater than 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 h old such a field at zero, corresponding to a false vacuum with energy density V-0 similar to m(2) M(2). When the temperature falls below V-0 (1/4), the thermal energy density becomes negligible and an era of the rmal 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 infl ation which does not affect the density perturbation generated during ordinary inflation. Thermal inflation can solve the Polonyi/moduli pro blem if M is within one or two orders of magnitude of 10(12) GeV.