Chaotic Inflation based on an Abelian D-flat Direction

We study the inflation due to the D-flat direction of an extra $U(1)$. This scenario is a hybrid of a right-handed sneutrino inflaton scenario and a gauge non-singlet inflaton scenario. The inflaton is a gauge non-singlet field which induces a right-handed neutrino mass spontaneously through an extra $U(1)$ D-flat direction. This right-handed neutrino mass can explain the solar neutrino problem. The reheating temperature resulting from the decay of the coherent oscillation of the right-handed sneutrino is sufficiently high so that the baryogenesis based on the lepton number asymmetry can be applicable. We also discuss the realistic model building.