Inflation in models with large extra dimension 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 the Cosmic Background Explorer can be obtained without any fine-tuning. The bulk inflaton then decays preferentially into brane Higgs fields and reheating follows.