Superconformal D-term inflation

Abstract

We study models of hybrid inflation in the framework of supergravitywith superconformal matter. F-term hybrid inflation is not viable since the inflatonacquires a large tachyonic mass. On the contrary, D-term hybrid inflation can successfully account forthe amplitude of the primordial power spectrum.It is a two-field inflation model which, depending on parameters,yields values of the scalar spectral index down tons ≃ 0.96. Generically, there is a tension between a small spectralindex and the cosmic string bound albeit,within 2σ uncertainty, the current observational bounds can be simultaneously fulfilled.