PERTURBATION SPECTRA FROM INTERMEDIATE INFLATION

We investigate models of 'intermediate' inflation, where the scale factor a(t) grows as a(t) = exp(At(f)), 0 < f < 1, A constant. These solutions arise as exact analytic solutions for a given class of potentials for the inflaton phi. For a simpler class of potentials falling off as a power of phi they arise as slow-roll solutions, and in particular they include, for f = 2/3, the class of potentials which give the Harrison-Zel'dovich spectrum. The perturbation spectral index n can be greater than unity on astrophysical scales. It is also possible to generate substantial gravitational waves while keeping the scalar spectrum close to scale invariance; this latter possibility performs well when confronted with most observational data.