Is the Standard Model Effective Field Theory Enough for Higgs Pair Production?

TL;DR

This paper compares SMEFT and HEFT frameworks for Higgs pair production, identifying regimes where each is appropriate and highlighting the potential of di-Higgs measurements to probe non-linear electroweak dynamics.

Contribution

It evaluates the validity of SMEFT and HEFT in describing Higgs pair production across different UV scenarios, providing guidance on their applicability.

Findings

HEFT can outperform SMEFT in certain parameter regimes.

Regimes where SMEFT and HEFT give similar predictions are identified.

Di-Higgs measurements can serve as probes of non-linear electroweak effects.

Abstract

We study Higgs-boson pair production in the Standard Model Effective Field Theory (SMEFT) up to dimension six and in the Higgs Effective Field Theory (HEFT) at leading order in the effective theory expansion, and assess which description is appropriate in concrete UV scenarios. Motivated by "Loryon"-inspired models, we compare the Higgs pair production cross sections predicted by the full models to their SMEFT and HEFT counterparts. We identify regimes in which the two EFTs provide comparable descriptions, and clarify the limits required for their couplings to match. We also find that, for parts of parameter space in some of these models, HEFT can reproduce Higgs pair production more accurately than SMEFT, highlighting di-Higgs measurements as a potential probe of non-linear electroweak dynamics.