Strong First Order Electroweak Phase Transition in the CP-Conserving 2HDM Revisited

TL;DR

This paper revisits the 2HDM to identify parameter regions that support a strong first order electroweak phase transition, with implications for baryogenesis and collider searches, using loop-corrected potentials and comprehensive constraints.

Contribution

It provides a systematic analysis of the 2HDM parameter space for strong phase transitions, incorporating loop corrections and current experimental constraints.

Findings

Identifies 2HDM regions compatible with a strong electroweak phase transition.

Shows a significant link between phase transition strength and collider phenomenology.

Suggests testable implications for LHC searches.

Abstract

The discovery of the Higgs boson by the LHC experiments ATLAS and CMS has marked a milestone for particle physics. Yet, there are still many open questions that cannot be answered within the Standard Model (SM). For example, the generation of the observed matter-antimatter asymmetry in the universe through baryogenesis can only be explained qualitatively in the SM. A simple extension of the SM compatible with the current theoretical and experimental constraints is given by the 2-Higgs-Doublet Model (2HDM) where a second Higgs doublet is added to the Higgs sector. We investigate the possibility of a strong first order electroweak phase transition in the CP-conserving 2HDM type I and type II where either of the CP-even Higgs bosons is identified with the SM-like Higgs boson. The renormalisation that we apply on the loop-corrected Higgs potential allows us to efficiently scan the 2HDM parameter space and simultaneously take into account all relevant theoretical and up-to-date experimental constraints. The 2HDM parameter regions found to be compatible with the applied constraints and a strong electroweak phase transition are analysed systematically. Our results show that there is a strong interplay between the requirement of a strong phase transition and collider phenomenology with testable implications for searches at the LHC.