Small Field Coleman-Weinberg Inflation driven by Fermion Condensate

TL;DR

This paper explores how fermion condensates and non-minimal gravity coupling can resolve key issues in small field Coleman-Weinberg inflation, such as low inflation scale and spectral index discrepancies.

Contribution

It introduces fermion condensates and non-minimal coupling effects as solutions to longstanding problems in small field CW inflation models.

Findings

Fermion condensates can address the low inflation scale issue.

Non-minimal coupling influences the inflation dynamics.

The combined effects improve agreement with observational data.

Abstract

We revisit the small field Coleman-Weinberg (CW) inflation, which has the following two problems. First, the smallness of the slow roll parameter $\epsilon$ requires the inflation scale to be very low. Second, the spectral index $n_s \approx1+2 \eta$ tends to become smaller compared to the observed value. In this letter, we consider two possible effects on the dynamics of inflation: radiatively generated non-minimal coupling to gravity $\xi \phi^2 {\cal R}$ and condensation of fermions coupled to the inflaton as $\phi \bar\psi \psi$. We show that the fermion condenate can solve the above problems.