Supercool exit: Gravitational waves from QCD-triggered conformal symmetry breaking

Classically conformal Standard Model extensions predict an intriguing thermal history of the early Universe. In contrast to common paradigm, onset electroweak phase transition can be significantly delayed while Universe undergoes a period inflation. Then, first-order chiral could not only trigger symmetry breaking but also initiate exit from supercooling. To study dynamics this scenario, we focus on low-energy quark-based QCD effective models that exhibit transition. While large amount latent heat is naturally involved if inflation ends, find supercooling prior scale considerably enhances timescale This enhancement implies great observational prospects at future gravitational wave observatories. Our results are readily applicable wide class scale-invariant SM extensions, as well strongly coupled dark sectors.