We construct a hybrid inflationary model associated with the superheavy scale $M_X\sim {10}^{16}$ 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.

• Received 13 January 1997

DOI:https://doi.org/10.1103/PhysRevD.55.R7335