2025/03/26 by D'Onofrio, Monica, Degens, Jordy, Gwilliam, Carl +3
paper · doi:10.17181/d1a0b-6x721
A feasibility study of the di-Higgs production channel at the FCC-hh has been conducted focusing on the hh → bb τ+ τ- final state. Both the leptonic-hadronic (ℓ-had) and fully hadronic (had-had) decays of the taus were considered, leveraging advanced Graph Neural Network (GNN) techniques for event classification. The analysis employed Graph Attention Networks (GATs), with each event represented as a fully connected graph, where nodes corresponded to reconstructed physics objects, and edges captured their relational properties. Additional complex features—such as invariant masses of b-jet and taus, angular separations, and transverse kinematic variables—were integrated to enhance event classification. This innovative application of GNNs significantly improved the ability to extract signal events, offering a powerful technique for precision Higgs self-coupling measurements at hh colliders. At 84 TeV centre-of-mass energy, the Higgs self-coupling could be constrained at the XXX% level using the had-had channel alone, and precise cross-section measurements will be possible in different invariant mass regions ( mhh < 350 GeV and mhh > 350 GeV). At 100 TeV the uncertainty improves by YYY%.