Exotic Higgs Decays and the Electroweak Phase Transition

TL;DR

This paper explores how light scalar particles can induce a strong first-order electroweak phase transition and argues that upcoming collider experiments will be able to conclusively test these scenarios through exotic Higgs decay searches.

Contribution

It demonstrates that light scalars with specific mass ranges and small Higgs mixing can be probed by future collider experiments, linking electroweak phase transition dynamics to observable Higgs decays.

Findings

Light scalars can drive a strong first-order EWPT.

High-luminosity LHC and future colliders can test these scenarios.

Exotic Higgs decay searches are well-motivated for probing new physics.

Abstract

Light new physics weakly coupled to the Higgs can induce a strong first-order electroweak phase transition (EWPT). Here, we argue that scenarios in which the EWPT is driven first-order by a light scalar with mass between $\sim 10$ GeV - $m_h/2$ and small mixing with the Higgs will be conclusively probed by the high-luminosity LHC and future Higgs factories. Our arguments are based on analytic and numerical studies of the finite-temperature effective potential and provide a well-motivated target for exotic Higgs decay searches at the LHC and future lepton colliders.