Higgs-portal assisted Higgs inflation with a sizeable tensor-to-scalar ratio

TL;DR

This paper demonstrates that Higgs portal interactions with an extra dark Higgs can stabilize Higgs inflation, allow a sizeable tensor-to-scalar ratio, and be tested at future colliders, aligning with Planck data.

Contribution

It introduces a novel mechanism where dark Higgs portal interactions enable Higgs inflation to be consistent with observations and predict a detectable tensor-to-scalar ratio.

Findings

Higgs portal interactions can stabilize the Higgs potential during inflation.

A tensor-to-scalar ratio in the range 0.08 to 0.1 is achievable.

Some parameter regions are testable at future collider experiments.

Abstract

We show that the Higgs portal interactions involving extra dark Higgs field can save generically the original Higgs inflation of the standard model (SM) from the problem of a deep non-SM vacuum in the SM Higgs potential. Specifically, we show that such interactions disconnect the top quark pole mass from inflationary observables and allow multi-dimensional parameter space to save the Higgs inflation, thanks to the additional parameters (the dark Higgs boson mass $m_{\phi}$, the mixing angle $\alpha$ between the SM Higgs $H$ and dark Higgs $\Phi$, and the mixed quartic coupling) affecting RG-running of the Higgs quartic coupling. The effect of Higgs portal interactions may lead to a larger tensor-to-scalar ratio, $0.08 \lesssim r \lesssim 0.1$, by adjusting relevant parameters in wide ranges of $\alpha$ and $m_{\phi}$, some region of which can be probed at future colliders. Performing a numerical analysis we find an allowed region of parameters, matching the latest Planck data.