Harnessing Higgs boson kinematics for HEFT constraints

We present a momentum-dependent reweighting strategy to extend current LHC di-Higgs analyses within the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>κ</a:mi></a:math> framework and Standard Model effective field theory into the bosonic sector of the Higgs effective field theory (HEFT). Unlike Standard Model effective field theory, where symmetry constraints tightly correlated 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 nonlinear Higgs dynamics. We generalize the interpretation of existing experimental analyses by integrating HEFT operators up to chiral dimension 4 into differential Monte Carlo reweighting. We quantify the sensitivity to representative HEFT operators using multidimensional likelihoods for Run 3 and project the reach at the high-luminosity LHC. Particular emphasis is placed on how different exclusive final states, such as <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>b</c:mi><c:mover accent="true"><c:mi>b</c:mi><c:mo stretchy="false">¯</c:mo></c:mover><c:mi>b</c:mi><c:mover accent="true"><c:mi>b</c:mi><c:mo stretchy="false">¯</c:mo></c:mover></c:math> and <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mi>b</i:mi><i:mover accent="true"><i:mi>b</i:mi><i:mo stretchy="false">¯</i:mo></i:mover><i:mi>γ</i:mi><i:mi>γ</i:mi></i:math>, 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.