Higgs pair production in gluon fusion to higher orders in Higgs Effective Field Theory

TL;DR

This paper investigates Higgs pair production via gluon fusion within the Higgs Effective Field Theory, emphasizing the importance of higher-dimensional operators and their impact on experimental search strategies.

Contribution

It demonstrates the necessity of including higher-dimensional operators at NLO in HEFT and re-evaluates benchmark scenarios for di-Higgs searches.

Findings

Higher-dimensional operators significantly affect Higgs pair production predictions.

Consistent power counting requires beyond-leading operators at NLO.

Reassessment of experimental benchmarks in light of additional contributions.

Abstract

Higgs pair production offers the opportunity to probe correlations among the couplings of one or two Higgs bosons to fermions and gauge bosons. In this context, it serves as a powerful test of the underlying Effective Field Theory (EFT) framework. In particular, while such couplings remain correlated in the Standard Model Effective Field Theory (SMEFT) at dimension six, they can become fully de-correlated in Higgs Effective Field Theory (HEFT) already at leading order in the EFT expansion. In this work, we study Higgs pair production via gluon fusion within the HEFT framework. We demonstrate that adopting a consistent power counting in combination with next-to-leading order (NLO) diagrams necessitates the inclusion of higher-dimensional operators beyond the leading ones. We analyze their phenomenological impact and re-assess critically the kinematic benchmark scenarios commonly used in experimental non-resonant di-Higgs searches in light of these additional contributions.