Primordial spectral indices from generalized Einstein theories.

Primordial spectral indices are calculated to second order in slow-roll parameters for three closely-related models of inflation, all of which contain a scalar field non-minimally coupled to the Ricci curvature scalar. In most cases, ns may be written as a function of the nonminimal curvature coupling strength ξ alone, with ns(ξ) ≤ 1, although the constraints on ξ differ greatly between ‘new inflation’ and ‘chaotic inflation’ initial conditions. Under ‘new inflation’ initial conditions, there are discrepancies between the values of ns as calculated in the Einstein frame and the Jordan frame. The sources for these discrepancies are addressed, and shown to have negligible effects on the numerical predictions for ns. No such discrepancies affect the calculations under ‘chaotic inflation’ initial conditions. PACS numbers: 98.80C, 04.50