Blue perturbation spectra from hybrid inflation with canonical supergravity

Abstract

We construct a hybrid inflationary model associated with the superheavy scale ${M}_{X}\ensuremath{\sim}{10}^{16}$ GeV of supersymmetric grand unified theories in which the inflaton potential is provided entirely by canonical supergravity. We find that the spectrum of adiabatic density perturbations is characterized by a strongly varying spectral index which is considerably larger than unity. Moreover, the total number of $e$-foldings is very limited. Implications of our analysis for other hybrid inflationary scenarios are briefly discussed.