Observational constraints on an inflation model with a running mass

We explore a model of inflation where the inflaton mass-squared is generated at a high scale by gravity-mediated soft supersymmetry breaking, and runs at lower scales to the small value required for slow-roll inflation. The running is supposed to come from the coupling of the inflaton to a non-Abelian gauge field. In contrast with earlier work, we do not constrain the magnitude of the supersymmetry breaking scale, and we find that the model might work even if squark and slepton masses come from gauge-mediated supersymmetry breaking. With the inflaton and gaugino masses in the expected range, and alpha = g(2)/4 pi in the range 10(-2)-10(-3) (all at the high scale), the model can give the observed cosmic microwave anisotropy and a spectral index in the observed range. The latter has a significant variation with scale, which can confirm or rule out the model in the foreseeable future. [S0556-2821(99)00714-6].