A Strongly First-Order Electroweak Phase Transition from Loryons

TL;DR

This paper investigates how BSM particles called Loryons, which derive most of their mass from Higgs coupling, can induce a strongly first-order electroweak phase transition, with implications for new physics and cosmology.

Contribution

It demonstrates that Loryons can significantly enhance the likelihood of a strongly first-order electroweak phase transition within current experimental constraints.

Findings

Loryons enlarge the parameter space for a strong first-order phase transition.

Loryons have a greater impact on the phase transition than non-Loryon BSM particles.

A sizable portion of allowed Loryon parameter space predicts a strong phase transition.

Abstract

We study the effect of BSM particles receiving most of their mass from their coupling to the Higgs boson ("Loryons") on the electroweak phase transition. The existence of BSM Loryons would imply that electroweak symmetry must be non-linearly realized in the effective theory of the Standard Model. Since, by definition, Loryons have a significant coupling to the Higgs, they are expected to have a significant effect on the Higgs effective potential and thereby the electroweak phase transition. We show that the BSM Loryon parameter space viable under current experimental and theoretical constraints overlaps heavily with the parameter space in which a strongly first-order phase transition is predicted. The portion of the experimentally allowed parameter space which gives a strongly first-order phase transition is significantly larger for Loryons as compared to non-Loryons.