Electroweak Phase Transition in Georgi-Machacek Model

TL;DR

This paper studies the electroweak phase transition in the Georgi-Machacek model, showing it can be strong enough for baryogenesis due to the triplet scalars' large vacuum expectation values.

Contribution

It evaluates the finite-temperature effective potential in the Georgi-Machacek model, demonstrating conditions for a strong electroweak phase transition with triplet VEVs around 10 GeV.

Findings

Electroweak phase transition can be sufficiently strong in the model.

Large triplet VEVs (~10 GeV) enable successful baryogenesis.

The model remains consistent with experimental bounds.

Abstract

The Georgi-Machacek model extends the standard model Higgs sector by adding two isospin triplet scalar fields and imposing global SU(2)$_R$ symmetry on them. A feature of the model is that the triplets can acquire a large vacuum expectation value without conflicting with the current experimental bound on the $\rho$ parameter. We investigate the electroweak phase transition in the Georgi-Machacek model by evaluating the finite-temperature effective potential of the Higgs sector. The electroweak phase transition can be sufficiently strong in a large parameter space when the triplets acquire a vacuum expectation value of $O(10)$ GeV, opening a possibility to realize successful electroweak baryogenesis.