Double and Triple Higgs Production to probe the Electroweak Phase Transition

TL;DR

This paper explores the potential of triple Higgs production at colliders as a probe for the electroweak phase transition, highlighting the impact of resonance effects and experimental prospects at the HL-LHC.

Contribution

It provides a phenomenological analysis of triple Higgs production in extended Higgs models, emphasizing resonance effects and constraints from current measurements.

Findings

Resonance contributions can significantly enhance triple Higgs production.

Enhancements of about 40 times the SM expectation are possible.

HL-LHC could set meaningful limits on triple Higgs production.

Abstract

The production of three Higgs bosons could be a stretch goal for the LHC and a strategic case for future colliders. In this work, we analyse the phenomenological prospects of (neutral) triple Higgs compared to di-Higgs boson production, for a range of Higgs-sector extensions from a strong first-order electroweak phase transition perspective. In parallel, we include constraints from existing exotics and Higgs boson measurements that further limit the parameter space of such models. Resonance contributions offer large modifications in particular for triple Higgs production, albeit starting from a small SM expectation. With enhancements of order 40 over the SM, however, experimental efforts to obtain limits at the HL-LHC are well-motivated and well-placed. This is further highlighted by the potential of these processes to inform the investigation of the thermal history of our universe.