Postinflationary scalar tensor cosmology and inflationary parameters

Scalar fields provide attractive modifications of pre-BBN cosmology, which have interesting implications for dark matter abundances. We analyze the effect of these modifications on the number of e-foldings between the horizon exit of cosmic microwave background modes and the end of inflation (N-k), and examine the consequences for inflationary predictions of various models. We find significant effects in the predictions in the (n(s), r); rthorn plane. For a large part of the parameter space, the shift in N-k is positive; this ameliorates the tension of m(2)phi(2) and natural inflation with data.