Gravitational Waves, Bubble Profile, and Baryon Asymmetry in the Complex 2HDM

TL;DR

This paper investigates how the complex Two Higgs Doublet Model can produce the Universe's baryon asymmetry through phase transitions, gravitational wave signals, and bubble profile analysis, highlighting the importance of accurate tunneling descriptions.

Contribution

It compares bubble profile approximation methods in baryon asymmetry calculations within the C2HDM, identifying significant discrepancies and a benchmark point consistent with observations.

Findings

Certain C2HDM parameter regions yield successful baryon asymmetry.

Differences between bubble profile approaches significantly affect asymmetry estimates.

A benchmark point consistent with observed baryon asymmetry was identified.

Abstract

This study explores the generation of the observed baryon asymmetry of the Universe within the complex Two Higgs Doublet Model (C2HDM) while considering theoretical and current experimental constraints. In our investigation, we analyze critical elements of the Higgs potential to understand the phase transition pattern. Specifically, we examine the formation of the barrier and the uplifting of the true vacuum state, which play crucial roles in facilitating a strong first-order phase transition. Furthermore, we explore the potential gravitational wave signals associated with this phase transition pattern and investigate the parameter space points that can be probed with LISA. Finally, we compare the impact of different approaches to describing the bubble profile on the calculation of the baryon asymmetry. We contrast the typically used kink profile approximation against the explicit solution of the tunneling profile. We find that a non-negligible range of the C2HDM parameter space results in significant discrepancies in the baryon asymmetry estimation between these two approaches. Through an examination of the parameter space, we identify a benchmark point that satisfies the observed baryon asymmetry.