Classically Scale Invariant Inflation, Supermassive WIMPs, and Adimensional Gravity

TL;DR

This paper presents a unified, scale-invariant model addressing the hierarchy problem, neutrino masses, dark matter, and inflation using an adimensional gravity framework, resulting in a consistent cosmological and particle physics scenario.

Contribution

It introduces a minimal scale-invariant model with adimensional gravity that simultaneously explains multiple fundamental issues in physics, including dark matter and inflation.

Findings

The model successfully generates the weak and Planck scales dynamically.

The pseudoscalar singlet acts as a stable WIMPzilla dark matter candidate.

The inflaton as a pseudo-Nambu-Goldstone boson leads to successful slow-roll inflation.

Abstract

We introduce a minimal and yet comprehensive framework with $CP$- and classical scale-symmetries, in order to simultaneously address the hierarchy problem, neutrino masses, dark matter, and inflation. One complex gauge singlet scalar and three flavors of the right-handed Majorana neutrinos are added to the standard model content, facilitating the see-saw mechanism, among others. An adimensional theory of gravity (Agravity) is employed, allowing for the trans-Planckian field excursions. The weak and Planck scales are induced by the Higgs portal and the scalar non-minimal couplings, respectively, once a Coleman-Weinberg dynamically-generated vacuum expectation value for the singlet scalar is obtained. All scales are free from any mutual quadratic destabilization. The $CP$-symmetry prevents a decay of the pseudoscalar singlet, rendering it a suitable WIMPzilla dark matter candidate with the correct observational relic abundance. Identifying the pseudo-Nambu-Goldstone boson of the (approximate) scale symmetry with the inflaton field, the model accommodates successful slow-roll inflation, compatible with the observational data. We reach the conclusion that a pseudo-Nambu-Goldstone inflaton, within a classically scale-symmetric framework, yields lighter WIMPzillas.