Dynamical tuning of the initial condition for new inflation in supergravity

We point out that for a class of 'new inflation' models in supergravity the required initial value of the inflaton field is dynamically set if there is another inflation ('pre-inflation') before the 'new inflation'. We study the dynamics of both inflatons by taking a hybrid inflation model for the 'pre-inflation' as an example. We find out that our 'new inflation' model provides reheating temperatures T-R similar or equal to 10 MeV-10(4) GeV low enough to avoid the gravitino problem even in gauge-mediated supersymmetry-breaking models. We also construct a model where the scale for the 'new inflation' is generated by nonperturbative dynamics of a supersymmetric gauge theory. (C) 1997 Published by Elsevier Science B.V.