Small field Coleman-Weinberg inflation driven by a fermion condensate

We revisit the small-field Coleman-Weinberg inflation, which has the following two problems: First, the smallness of the slow roll parameter ɛ requires the inflation scale to be very low. Second, the spectral index n_s≈1 +2 η tends to become smaller compared to the observed value. In this paper, we consider two possible effects on the dynamics of inflation: radiatively generated nonminimal coupling to gravity ξ ϕ²R and condensation of fermions coupled to the inflaton as ϕ ψ ¯ψ . We show that the fermion condensate can solve the above problems.