Multi-scale cross-attention transformer encoder for event classification

Abstract

We deploy an advanced Machine Learning (ML) environment, leveraging a multi-scale cross-attention encoder for event classification, towards the identification of the gg→H→hh→bb¯bb¯ process at the High Luminosity Large Hadron Collider (HL-LHC), where h is the discovered Standard Model (SM)-like Higgs boson and H a heavier version of it (with mH>2mh). { In the ensuing boosted Higgs regime, the final state consists of two fat jets. Our multi-modal network can extract information from the jet substructure and the kinematics of the final state particles through self-attention transformer layers. The diverse learned information is subsequently integrated to improve classification performance using an additional transformer encoder with cross-attention heads.} We ultimately prove that our approach surpasses in performance current alternative methods used to establish sensitivity to this process, whether solely based on kinematic analysis or else on a combination of this with mainstream ML approaches. {Then, we employ various interpretive methods to evaluate the network results, including attention map analysis and visual representation of Gradient-weighted Class Activation Mapping (Grad-CAM). Finally, we note that the proposed network is generic and can be applied to analyse any process carrying information at different scales.} Our code is publicly available for generic use.

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Identifiers

ORCID for S. Moretti: orcid.org/0000-0002-8601-7246

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