F-term, D-term and hybrid brane inflation

We study inflation and reheating in models for the brane universe, considering hybrid brane inflation without tachyon condensation. We expect that some fields that are localized on different branes interact with O(1) coupling when branes are on top of each other, while the interaction vanishes when branes are separated at a distance. If the interaction is needed to avoid spontaneous breaking of supersymmetry on the brane, our idea for hybrid brane inflation works. In our model, when branes are far apart, supersymmetry is spontaneously broken by the fields on a brane, which induces inflation. The inflaton field is the moduli for the brane distance. At the end of inflation, when branes come close, supersymmetry is restored by the interaction between fields on the branes, then the oscillation starts to reheat the Universe. In this paper we construct explicit models for F-term and D-term inflation. There are at least two major advantages. The most attractive point is that reheating is natural in our model, because the trigger field is not the tachyon but a conventional field on the brane. The serious constraint from the loop correction, which always appears in conventional models for hybrid inflation, is avoided.