Preheating with non-minimally coupled scalar fields in higher-curvature inflation models

Abstract

In higher-curvature inflation models ($R+α_n R^n$), we study a parametric preheating of a scalar field $χ$ coupled non-minimally to a spacetime curvature $R$ ($ξR χ^2$). In the case of $R^2$-inflation model, efficient preheating becomes possible for rather small values of $ξ$, i.e. $|ξ|< several. Although the maximal fluctuation $\sqrt{< χ^2 >}_{max} \approx 2 \times10^{17}$ GeV for $ξ\approx -4$ is almost the same as the chaotic inflation model with a non-minimally coupled $χ$ field, the growth rate of the fluctuation becomes much larger and efficient preheating is realized. We also investigate preheating for $R^4$ model and find that the maximal fluctuation is $\sqrt{< χ^2 >}_{max} \approx 8 \times 10^{16}$ GeV for $ξ\approx -35$.