Electroweak phase transition with composite Higgs models: calculability, gravitational waves and collider searches

TL;DR

This paper investigates the conditions for a strong first order electroweak phase transition in composite Higgs models, exploring gravitational wave signals and collider signatures, and emphasizing the need for contributions beyond minimal potential assumptions.

Contribution

It demonstrates that a strong first order electroweak phase transition requires additional contributions beyond minimal scalar potentials in composite Higgs models, and analyzes gravitational waves and collider phenomenology.

Findings

Minimal Higgs potential hypothesis cannot trigger SFOEWPT.

Additional local operators are necessary for SFOEWPT.

Gravitational wave signals are predicted in specific models.

Abstract

We study the strong first order electroweak phase transition (SFOEWPT) with the $SO(6)/SO(5)$ composite Higgs model, whose scalar sector contains one Higgs doublet and one real singlet. Six benchmark models are built with fermion embeddings in $\textbf{1}$, $\textbf{6}$, and $\textbf{15}$ of $SO(6)$. We show that SFOEWPT cannot be triggered under the minimal Higgs potential hypothesis, which assumes the scalar potential is dominated by the form factors from the lightest composite resonances. To get a SFOEWPT, the contributions from local operators induced by physics above the cutoff scale are needed. We take the $\textbf{6}+\textbf{6}$ model as an example to investigate the gravitational waves prediction and the related collider phenomenology.