Thermal inflation and the moduli problem

In supersymmetric theories a field can develop a vacuum expectation value 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 hold 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 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) GeV.