Enlarging the parameter space of standard hybrid inflation

Abstract

We show that the parameter space for F-term inflation which predict the formation of cosmic strings is larger than previously estimated. Firstly, because realistic embeddings in GUT theories alter the standard scenerio, making the inflationary potential less steep. Secondly, the strings which form at the end of inflation are not necessarily topologically stable down to low scales. In shifted and smooth inflation strings do not form at all. We also discuss D-term inflation; here the possibilities are much more limited to enlargen paramer space.