Phase Transitions in Twin Higgs Models

TL;DR

This paper investigates phase transitions in twin Higgs models at finite temperature, revealing challenges for electroweak baryogenesis and predicting gravitational wave signals that are difficult to detect, thus constraining model parameters.

Contribution

It provides a detailed analysis of cosmological phase transitions in twin Higgs models, including the conditions for first order transitions and gravitational wave production, with new insights into supersymmetric cases.

Findings

Electroweak phase transition is non-perturbative and unlikely for baryogenesis.

First order phase transition occurs only in supersymmetric scenarios.

Gravitational wave background from the transition is undetectable by DECIGO or BBO.

Abstract

We study twin Higgs models at non-zero temperature and discuss cosmological phase transitions as well as their implications on electroweak baryogenesis and gravitational waves. It is shown that the expectation value of the Higgs field at the critical temperature of the electroweak phase transition is much smaller than the critical temperature, which indicates two important facts: (i) the electroweak phase transition cannot be analyzed perturbatively (ii) the electroweak baryogenesis is hardly realized in the typical realizations of twin Higgs models. We also analyze the phase transition associated with the global symmetry breaking, through which the Standard Model Higgs is identified with one of the pseudo-Nambu-Goldstone bosons in terms of its linear realization, with and without supersymmetry. For this phase transition, we show that, only in the supersymmetric case, there are still some parameter spaces, in which the perturbative approach is validated and the phase transition is the first order. We find that the stochastic gravitational wave background is generated through this first order phase transition, but it is impossible to be detected by DECIGO or BBO in the linear realization and the decoupling limit. The detection of stochastic gravitational wave background with the feature of first order phase transition, therefore, will give strong constraints on twin Higgs models.