Axionlike particle-assisted supercooling chiral phase transition in QCD: Identifying Coleman-Weinberg type-chiral phase transition in QCD-like scenarios

TL;DR

This paper introduces a new QCD cosmological scenario involving a Coleman-Weinberg type chiral phase transition, predicting a heavy axion-like particle and potential gravitational wave and black hole signatures.

Contribution

It proposes a novel mechanism for chiral phase transition in QCD with an associated heavy ALP, opening new avenues for cosmological and particle physics searches.

Findings

Predicts a 5 MeV axion-like particle consistent with current bounds.

Suggests rich cosmological epochs including mini-inflation and black hole formation.

Revisits existing supercooling scenarios in QCD with scale anomaly considerations.

Abstract

We propose a new scenario to realize the Coleman-Weinberg (CW) type chiral phase transition in the QCD thermal history. This scenario predicts a heavy axionlike particle (ALP) with mass $\sim$ 5 MeV, consistently with the current experimental and cosmological bounds. The chiral phase transition is evaluated by monitoring ordinary QCD setup in a view of a two-flavor Nambu-Jona-Lasinio model including a simplified meson fluctuation contribution. The present work thus can open a new window to search for the ALP associated with the QCD phase transition epoch of the thermal history. The new QCD cosmological scenario potentially predicts rich epochs around the QCD scale: a mini-inflation; a nonperturbative preheating and/or reheating, which can provide characteristic gravitational wave and primordial black hole productions. This proposal is based on a generic classification of the order of the chiral phase transition at the level of the mean field approximation in view of the scale violation classes: the soft-scale breaking term and the CW-type scale anomaly term, in or off the medium with or without chemical potentials. On this theoretical ground, we also revisit existing scenarios which undergo the supercooling chiral phase transition, such as nearly scale-invariant QCD and QCD with a large baryon chemical potential.