Researchers have investigated the sensitivity to the Higgs self-coupling through W boson fusion di-Higgs production at the Compact Linear Collider (CLIC), operating at a center-of-mass energy of 3 TeV. This study focuses on the interplay between the Higgs self-coupling modifier (κ_λ) and the Higgs-gauge coupling modifiers (κ_V and κ_2V) within the κ framework. The results demonstrate that future high-energy lepton colliders, combined with advanced machine learning techniques, offer exceptional sensitivity to the Higgs self-coupling, significantly exceeding the projections of the High-Luminosity Large Hadron Collider (HL-LHC).

To enhance the separation between signal and background, the team developed a classifier based on graph neural networks (GNNs). This approach allowed them to achieve a signal significance of approximately 20σ with an integrated luminosity of 5 ab⁻¹. This level of precision is crucial for disentangling the nature of electroweak symmetry breaking, distinguishing between linearly and non-linearly realized scenarios, and provides a powerful tool for the search for new physics in the electroweak sector.

The Higgs boson self-coupling is a fundamental parameter that governs the shape of the Higgs potential and, therefore, the mechanism of electroweak symmetry breaking. Its precise measurement is essential for confirming the Standard Model and for searching for deviations that could indicate the presence of particles or interactions beyond it. The capability of CLIC, coupled with GNNs, to probe this coupling with such precision opens new avenues for exploring fundamental phenomena in particle physics.