We discuss how the non-minimal coupling $\xi\phi^2R$ between the inflaton and the Ricci scalar affects the predictions of single field inflation models where the inflaton has a non-zero vacuum expectation value (VEV) $v$ after inflation. We show that, for inflaton values both above the VEV and below the VEV during inflation, under certain conditions the inflationary predictions become approximately the same as the predictions of the Starobinsky model. We then analyze inflation with double-well and Coleman-Weinberg potentials in detail, displaying the regions in the $v$-$\xi$ plane for which the spectral index $n_s$ and the tensor-to-scalar ratio $r$ values are compatible with the current observations. $r$ is always larger than 0.002 in these regions. Finally, we consider the effect of $\xi$ on small field inflation (hilltop) potentials.
N. Bostan, O. Guleryuz and V. Senoguz
Tue, 13 Feb 18
Comments: 1+21 pages, 9 figures