Electroweak phase transition with the confinement scale of the strong sector or dilaton in the minimal composite Higgs model

TL;DR

The paper analyzes the electroweak phase transition within the Minimal Composite Higgs Model (MCHM), investigating triggers from the confinement scale $f$ and from a dynamical dilaton $χ$. Using a one-loop effective potential with finite-temperature corrections, it shows that a first-order EWPT is challenging to achieve with $f$ alone, but introducing a dilaton can enhance the transition strength $S$ to values above unity for plausible mass ranges. The Higgs-dilaton framework yields a richer potential landscape, with $m_χ$ in the few-hundred GeV range enabling $S$ between 1 and about 3, and $χ$ approaching its minimum as $m_χ$ grows. The results suggest that the dilaton is a viable mechanism to realize electroweak baryogenesis in CHMs and outline directions for further constraints and phenomenology, including sphaleron analyses and experimental implications.

Abstract

The minimal Composite Higgs model (MCHM) provides an effective trigger for the Baryogenesis scenario through the confinement scale of the strong sector ($f$) or dilaton ($χ$). $f$ is a parameter with mass dimension, which stores the resonances of particles at high energies and has a suitable value of about $800$ GeV. But when $300$ GeV $\le f \le 400$ GeV, the effective Higgs potential has a first-order electroweak phase transition. Therefore, although $f$ cannot be a perfect trigger, it does suggest an effective approach that accommodates the resonances of particles. Thus the investigation of the electroweak phase transition according to $f$ has confirmed that the inclusion of the dilaton in the effective potential is reasonable. Accordingly, we derive a dilaton potential with appropriate parameter domains and $f=800$ GeV; the mass of the dilaton ranges from $300$ GeV to $700$ GeV, which will give an electroweak phase transition strength greater than $1$ and less than $3$, enough for a first-order phase transition. This is a direct and clear evidence of the triggers for the first-order EWPT in the MCHM.

Figures (4)

• Figure 1: Plots of the effective potential at 0K in SM and MCHM for two different $\epsilon$ values.
• Figure 2: Plot of phase transition intensity in the CHM versus $f$ (purple) and in the SM (blue) in the range from $300$ GeV to $1$ TeV.
• Figure 3: The dilaton potential at the dilaton masses are $400$ GeV, $500$ GeV and $600$ GeV (from top to bottom), respectively).
• Figure 5: Phase transitions with dilaton masses in the range from $300$ GeV to $800$ GeV.