The Electro-Weak Phase Transition at Colliders: Discovery Post-Mortem

TL;DR

This paper assesses how a future 100 TeV proton collider could investigate the electroweak phase transition by studying a minimal scalar extension of the Standard Model, with implications for cosmology and gravitational waves.

Contribution

It develops phenomenological methods to measure properties of a new scalar particle and explores collider constraints on the electroweak phase transition within the minimal singlet scalar model.

Findings

A 100 TeV collider can constrain the parameter space of the singlet scalar model.

Certain conditions are necessary for a strong first-order electroweak phase transition.

Additional data from multi-scalar processes and gravitational waves are likely needed.

Abstract

We explore the capabilities of a future proton collider to probe the nature of the electro-weak phase transition, following the hypothetical discovery of a new scalar particle. We focus on the real singlet scalar field extension of the Standard Model, representing the most minimal, and challenging to probe, framework that can enable a strong first-order electro-weak phase transition. By constructing detailed phenomenological methods for measuring the mass and accessible couplings of the new scalar particle, we find that a 100 TeV proton collider has the potential to explore the parameter space of the real singlet model and provide meaningful constraints on the electro-weak phase transition. We empirically find some necessary conditions for the realization of a strong first order electro-weak phase transition and conjecture that additional information, including through multi-scalar processes and gravitational wave detectors, are likely needed to gauge the nature of the cosmological electro-weak transition. This study represents the first crucial step towards solving the inverse problem in the context of the electro-weak phase transition.