Harnessing Higgs Kinematics for HEFT Constraints

TL;DR

This paper develops a momentum-dependent reweighting method to extend di-Higgs analyses to the Higgs Effective Field Theory, enabling more comprehensive probes of non-linear Higgs dynamics at the LHC.

Contribution

It introduces a novel reweighting strategy to incorporate HEFT operators into existing analyses, broadening the scope of Higgs sector studies beyond SMEFT constraints.

Findings

Enhanced sensitivity to HEFT operators at Run 3 and HL-LHC.

Different final states provide complementary constraints on HEFT deviations.

Rare processes like four-top production offer orthogonal probes.

Abstract

We present a momentum-dependent reweighting strategy to extend current LHC di-Higgs analyses within the $\kappa$-framework and SMEFT into the bosonic sector of the Higgs Effective Field Theory (HEFT). Unlike SMEFT, where symmetry constraints tightly correlate multi-Higgs processes, HEFT allows for a broader range of momentum-dependent deviations that can substantially impact di-Higgs kinematics and offer a powerful probe of non-linear Higgs dynamics. We generalise the interpretation of existing experimental analyses by integrating HEFT operators up to chiral dimension four into differential Monte Carlo reweighting. We quantify the sensitivity to representative HEFT operators using multi-dimensional likelihoods for Run 3 and project the reach at the High-Luminosity LHC (HL-LHC). Particular emphasis is placed on how different exclusive final states, such as $b\bar{b}b\bar{b}$ and $b\bar{b}\gamma\gamma$, respond to momentum enhancements and how their complementary event selections drive exclusion limits. We further explore how rare final states, especially four-top production, can provide orthogonal constraints on HEFT-induced modifications, thereby enhancing global sensitivity to new physics effects in the Higgs sector.