Minimal but non-minimal inflation and electroweak symmetry breaking

TL;DR

This paper proposes a minimal scale-invariant extension of the Standard Model with an extra scalar singlet that drives inflation and electroweak symmetry breaking, predicting specific inflationary parameters and compatible collider phenomenology.

Contribution

It introduces a minimal model with a scalar singlet for inflation and electroweak symmetry breaking, differing from existing models by its spectral index prediction and non-minimal coupling.

Findings

Predicts a low tensor-to-scalar ratio r ≈ 10^{-3}

Finds a scalar spectral index n_s ≈ 0.97, deviating from Starobinsky

Compatible with current experimental bounds

Abstract

We consider the most minimal scale invariant extension of the standard model that allows for successful radiative electroweak symmetry breaking and inflation. The framework involves an extra scalar singlet, that plays the r\^ole of the inflaton, and is compatibile with current experimental bounds owing to the non-minimal coupling of the latter to gravity. This inflationary scenario predicts a very low tensor-to-scalar ratio $r \approx 10^{-3}$, typical of Higgs-inflation models, but in contrast yields a scalar spectral index $n_s \simeq 0.97$ which departs from the Starobinsky limit. We briefly discuss the collider phenomenology of the framework.