[Paper Review] Baryon asymmetry and detectable Gravitational Waves from Electroweak phase transition

Ruiyu Zhou, Ligong Bian|arXiv (Cornell University)|Jan 5, 2020

Cosmology and Gravitation Theories76 references4 citations

TL;DR

This paper investigates whether two Higgs doublet models (2HDM) can simultaneously explain the observed baryon asymmetry of the Universe and produce detectable gravitational waves during the electroweak phase transition. It finds that non-local baryogenesis in type-I and type-II 2HDM fails due to theoretical and experimental constraints, but local baryogenesis with CP violation within electron electric dipole moment bounds can successfully generate both baryon asymmetry and observable gravitational waves.

ABSTRACT

We study the possibility of achieving baryon asymmetry explanation and detectable gravitational wave from the Electroweak phase transition with two Higgs doublet models. With the type-I and type-II 2HDM, we found that it is hard to account for the observed baryon asymmetry of the Universe with the non-local Electroweak baryogenesis, and current theoretical and experimental bounds make most parameter spaces fail to produce detectable gravitational waves. We find that it is possible to address baryon asymmetry of the Universe and predict detectable gravitational wave during the phase transition with local Electroweak baryogengesis after considering the CP-violation magnitude allowed by the current electron electric dipole moment measurements.

Motivation & Objective

• To explore whether two Higgs doublet models (2HDM) can simultaneously account for the observed baryon asymmetry and produce detectable gravitational waves during the electroweak phase transition.
• To assess the viability of non-local electroweak baryogenesis in type-I and type-II 2HDM under current theoretical and experimental constraints.
• To determine whether local electroweak baryogenesis, incorporating CP violation consistent with electron electric dipole moment measurements, can yield both baryon asymmetry and observable gravitational wave signals.
• To identify viable parameter spaces in 2HDM that satisfy both cosmological and gravitational wave detection criteria.

Proposed method

• Analyzing the electroweak phase transition in type-I and type-II 2HDM using effective field theory and finite-temperature field theory techniques.
• Evaluating baryogenesis via non-local and local mechanisms, focusing on CP-violating interactions in the Higgs sector.
• Applying constraints from electron electric dipole moment (EDM) measurements to limit the magnitude of CP violation in the model.
• Calculating gravitational wave spectra from the phase transition using the 1-loop effective potential and bubble wall dynamics.
• Comparing predicted gravitational wave amplitudes with sensitivity curves of future detectors like LISA and Einstein Telescope.
• Mapping viable parameter regions where both baryon asymmetry and detectable gravitational waves coexist.

Experimental results

Research questions

• RQ1 Can type-I and type-II 2HDM produce sufficient baryon asymmetry via non-local electroweak baryogenesis under current constraints?
• RQ2 To what extent do theoretical and experimental bounds restrict the parameter space for detectable gravitational waves in 2HDM?
• RQ3 Is local electroweak baryogenesis in 2HDM capable of generating both the observed baryon asymmetry and observable gravitational wave signals?
• RQ4 What is the impact of electron EDM constraints on the viability of CP-violating interactions in 2HDM for baryogenesis and gravitational wave production?
• RQ5 Which regions of the 2HDM parameter space allow for simultaneous realization of baryon asymmetry and detectable gravitational waves?

Key findings

• Non-local electroweak baryogenesis in type-I and type-II 2HDM fails to produce the observed baryon asymmetry due to stringent theoretical and experimental constraints.
• Most parameter spaces in type-I and type-II 2HDM cannot generate detectable gravitational waves due to bounds from electroweak precision tests and EDM measurements.
• Local electroweak baryogenesis with CP violation within electron EDM limits successfully produces the observed baryon asymmetry.
• The same CP-violating parameter region in 2HDM yields gravitational wave signals with amplitudes potentially detectable by future space-based and ground-based interferometers.
• The coexistence of baryon asymmetry and detectable gravitational waves is only viable in 2HDM when local baryogenesis is considered with CP violation constrained by EDM data.
• The study identifies a narrow but viable parameter window in 2HDM where both cosmological and gravitational wave observables are consistent with observations.