The 750 GeV Resonance as Non-Minimally Coupled Inflaton: Unitarity Violation and Why the Resonance is a Real Singlet Scalar

TL;DR

This paper proposes that the 750 GeV resonance can be explained as a non-minimally coupled real singlet scalar, which avoids unitarity violation issues during inflation better than Higgs or complex singlet models.

Contribution

It demonstrates that a real singlet scalar with large non-minimal coupling can serve as a viable inflaton candidate, maintaining unitarity during inflation.

Findings

Real singlet scalar allows larger unitarity violation scale during inflation.

Unitarity violation scale is much larger than the inflaton field during inflation.

Supports the 750 GeV resonance as a real singlet scalar inflaton candidate.

Abstract

The 750 GeV resonance observed by ATLAS and CMS may be explained by a gauge singlet scalar. This would provide an ideal candidate for a gauge singlet scalar alternative to Higgs Inflation, S-inflation. Here we discuss the relevant results of S-inflation in the context of the 750 GeV resonance. In particular, we show that a singlet scalar, if it is real, has a major advantage over the Higgs boson with regard to unitarity violation during inflation. This is because it is possible to restrict the large non-minimal coupling required for inflation, $\xi \sim 10^5$, to the real singlet scalar, with all other scalars having $\xi \sim 1$. In this case the scale of unitarity violation $\Lambda$ is much larger than the inflaton field during inflation. This protects the inflaton effective potential from modification by the new physics or strong coupling which is necessary to restore unitarity, which would otherwise invalidate the perturbative effective potential based on Standard Model physics. This is in contrast to the case of Higgs Inflation or models based on complex singlet scalars, where the unitarity violation scale during inflation is less than or of the order of the inflaton field. Therefore if the 750 GeV resonance is the inflaton, it must be a non-minimally coupled real singlet scalar.