Reheating the FCC: Probing Early Matter Domination with Long-Lived Particles

2026/07/22 by Nicolás Bernal, Giovanna Cottin, Kuldeep Deka +1
#hep-ph #hep-ex

paper · pdf

Abstract

We study a GeV-scale Higgs-portal scalar ϕ that can dominate the early Universe and later decay into Standard Model states, ending an early matter-dominated era. Ordinary cosmic reheating is the minimal example of this scenario. The small Higgs mixing makes ϕ a long-lived particle (LLP), linking the reheating temperature T_rh to displaced-decay signatures at colliders. Including finite-temperature suppression of the decay width, we map FCC-hh LLP sensitivity onto the [m_ϕ, T_rh] plane. We find that FCC-hh displaced searches could probe GeV-scale transition temperatures, up to the electroweak scale within the broken-phase Higgs-portal description.

Citations

• FeynRules 2.0 — A complete toolbox for tree-level phenomenology

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