Resonant particle production with non-minimally coupled scalar fields in preheating after inflation

TL;DR

This paper studies how non-minimal coupling of scalar fields to curvature affects resonant particle production during preheating after inflation, revealing parameter regimes where the coupling enhances or suppresses resonance.

Contribution

It provides a detailed analysis of the effects of non-minimal coupling on particle production during preheating, highlighting conditions that enhance or suppress resonance.

Findings

Non-minimal coupling can assist resonance for small g values.

For larger g, the coupling suppresses resonance due to back reaction.

Maximal fluctuation of produced particles can reach 2×10^{17} GeV for certain parameters.

Abstract

We investigate a resonant particle production of a scalar field $\chi$ coupled non-minimally to a spacetime curvature $R$ ($\xi R \chi^2$) as well as to an inflaton field $\phi$ ($g^2\phi^2\chi^2$). In the case of $g < 3 \times 10^{-4}$, $\xi$ effect assists $g$-resonance in certain parameter regimes. However, for $g > 3 \times 10^{-4}$, $g$-resonance is not enhanced by $\xi$ effect because of $\xi$ suppression effect as well as a back reaction effect. If $\xi \approx -4$, the maximal fluctuation of produced $\chi$-particle is $\sqrt{< \chi^2 >}_{max} \approx 2 \times 10^{17}$ GeV for $g < 1 \times 10^{-5}$, which is larger than the minimally coupled case with $g \approx 1 \times 10^{-3}$.