# The Higgs Vacuum Uplifted: Revisiting the Electroweak Phase Transition with a Second Higgs Doublet

## TL;DR

This paper investigates how a second Higgs doublet can induce a first order electroweak phase transition, potentially explaining matter-antimatter asymmetry, and identifies collider signatures of such a scenario.

## Contribution

It demonstrates the correlation between a first order phase transition and Higgs vacuum uplift in a two-Higgs-doublet model, and predicts observable collider signals.

## Key findings

- A strongly first order phase transition correlates with a significant Higgs vacuum uplift.
- Decay $A_0
ightarrow H_0 Z$ is a key collider signature.
- Deviations in Higgs self-coupling $ ext{lambda}_{hhh}$ indicate phase transition strength.

## Abstract

The existence of a second Higgs doublet in Nature could lead to a cosmological first order electroweak phase transition and explain the origin of the matter-antimatter asymmetry in the Universe. We explore the parameter space of such a two-Higgs-doublet-model and show that a first order electroweak phase transition strongly correlates with a significant uplifting of the Higgs vacuum w.r.t. its Standard Model value. We then obtain the spectrum and properties of the new scalars $H_0$, $A_0$ and $H^{\pm}$ that signal such a phase transition, showing that the decay $A_0 \rightarrow H_0 Z$ at the LHC and a sizable deviation in the Higgs self-coupling $\lambda_{hhh}$ from its SM value are sensitive indicators of a strongly first order electroweak phase transition in the 2HDM.