Inflation in Models with Large Extra Dimensions Driven by a Bulk Scalar Field

We discuss inflation in models with large extra dimensions, driven by a bulk scalar field. The brane inflaton is then a single effective field, obtained from the bulk scalar field by scaling. The self interaction terms of the effective brane inflaton are then naturally suppressed. The picture is consistent with a fundamental string scale in the TeV range without the problem of a superlight inflaton. If hybrid inflation is considered, the right prediction for the density perturbations as observed by COBE can be obtained without any fine tunning. The bulk inflaton then decays preferentially into brane Higgses and reheating follows.