Enlarging the parameter space of standard hybrid inflation

Abstract

We show that the parameter space forF-term inflation which predicts the formation of cosmic strings is larger than previouslyestimated, firstly, because realistic embeddings in GUT theories alter the standard scenario,making the inflationary potential less steep and, secondly, because the strings whichform at the end of inflation are not necessarily topologically stable down to lowscales. In shifted and smooth inflation, strings do not form at all. We also discussD-term inflation; here the possibilities are much more limited for enlarging the parameterspace.