The Electro-Weak Phase Transition at Colliders: Confronting Theoretical Uncertainties and Complementary Channels

TL;DR

This paper assesses how future colliders can investigate the electroweak phase transition, focusing on a minimal scalar extension of the Standard Model, and highlights the potential for early discovery of new physics at high energies.

Contribution

It demonstrates the capability of 100 TeV and 27 TeV colliders to probe the electroweak phase transition within a minimal scalar extension, considering theoretical uncertainties and search channels.

Findings

100 TeV collider can confirm or falsify a strong first-order transition

Lower-energy colliders can probe significant parts of the parameter space

Early discoveries could enable precise measurements of new scalar phenomena

Abstract

We explore and contrast the capabilities of future colliders to probe the nature of the electro-weak phase transition. We focus on the real singlet scalar field extension of the Standard Model, representing the most minimal, yet most elusive, framework that can enable a strong first-order electro-weak phase transition. By taking into account the theoretical uncertainties and employing the powerful complementarity between gauge and Higgs boson pair channels in the searches for new scalar particles, we find that a 100 TeV proton collider has the potential to confirm or falsify a strong first-order transition. Our results hint towards this occurring relatively early in its lifetime. Furthermore, by extrapolating down to 27 TeV, we find that a lower-energy collider may also probe a large fraction of the parameter space, if not all. Such early discoveries would allow for precise measurements of the new phenomena to be obtained at future colliders and would pave the way to definitively verify whether this is indeed the physical remnant of a scalar field that catalyses a strong first-order transition.