Modified hybrid inflation, reheating and stabilization of the electroweak vacuum

We propose a modification to the standard hybrid inflation model \cite{Linde:1993cn}, that connects a successful hybrid inflation scenario to the standard model higgs sector, via the electroweak vacuum stability. The proposed model results in an effective inflation potential of a hilltop-type, with both the trans-Planckian and sub-Planckian inflation regimes are consistent with the recent Planck/BICEP combined results. Reheating via the inflation sector decays to right-handed neutrinos is considered. An upper bound on the reheating temperature $T_{\rm R} \leq 2\times 10^{11}~(1\times 10^{13})$ GeV, for large~(small) field inflation, will suppress contributions from one-loop quantum corrections to the inflation potential. This may push the neutrino Yukawa couplings to be ${\cal O}(1)$ and affect the vacuum stability. We show that the couplings of the SM Higgs to the inflation sector can guarantee the electroweak vacuum stability up to Planck scale. The so-called hybrid Higgs-inflaton model leads to a positive correction for the Higgs quartic coupling at a threshold scale, which is shown to have a very significant effect in stabilizing the electroweak vacuum. We find that even with ${\cal O}(1)$ neutrino Yukawa couplings, threshold corrections leave the SM vacuum stability intact.