EXTENDED INFLATION WITH A CURVATURE-COUPLED INFLATON

We examine extended inflation models enhanced by the addition of a cou pling between the inflaton field an& the space-time curvature. We exam ine two types of model, where the underlying inflaton potential takes on second-order and first-order forms, respectively. One aim is to pro vide models which satisfy the solar system constraints on the Brans-Di cke parameter omega. This constraint has proven very problematic in pr evious extended inflation models, and we find circumstances where it c an be successfully evaded, though the constraint must be carefully ass essed in our model and can be much stronger than the usual omega > 500 . In the simplest versions of the model, one may avoid the need to int roduce a mass for the Brans-Dicke field in order to ensure that it tak es on the correct value at the present epoch, as seems to be required in hyperextended inflation. We also briefly discuss aspects of the for mation of topological defects in the inflaton field itself.