Why Is Attention Sparse In Particle Transformer?

Fuente: arXiv
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Autori principali: Legge, Timothy, Wang, Aaron, Ortiz, Jacob, Limouzi, Victor, Zhao, Zihan, Gandrakota, Abhijith, Khoda, Elham E., Ngadiuba, Jennifer, Duarte, Javier, Cavanaugh, Richard
Natura: Preprint
Pubblicazione: 2025
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author Legge, Timothy
Wang, Aaron
Ortiz, Jacob
Limouzi, Victor
Zhao, Zihan
Gandrakota, Abhijith
Khoda, Elham E.
Ngadiuba, Jennifer
Duarte, Javier
Cavanaugh, Richard
author_facet Legge, Timothy
Wang, Aaron
Ortiz, Jacob
Limouzi, Victor
Zhao, Zihan
Gandrakota, Abhijith
Khoda, Elham E.
Ngadiuba, Jennifer
Duarte, Javier
Cavanaugh, Richard
contents Transformer-based models have achieved state-of-the-art performance in jet tagging at the CERN Large Hadron Collider (LHC), with the Particle Transformer (ParT) representing a leading example of such models. A striking feature of ParT is its sparse, nearly binary, attention structure, raising questions about the origin of this behavior and whether it encodes physically meaningful correlations. In this work, we investigate the source of ParT's sparse attention by comparing models trained on multiple benchmark datasets and examine the relative contributions of the attention term and the physics-inspired interaction matrix before softmax. We find that binary sparsity arises primarily from the attention mechanism itself, with the interaction matrix playing a secondary role. Moreove, we show that ParT is able to identify key jet substructure elements, such as leptons in semileptonic top decays, even without explicit particle identification inputs. These results provide new insight into the interpretability of transformer-based jet taggers and clarify the conditions under which sparse attention patterns emerge in ParT.
format Preprint
id arxiv_https___arxiv_org_abs_2512_00210
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Why Is Attention Sparse In Particle Transformer?
Legge, Timothy
Wang, Aaron
Ortiz, Jacob
Limouzi, Victor
Zhao, Zihan
Gandrakota, Abhijith
Khoda, Elham E.
Ngadiuba, Jennifer
Duarte, Javier
Cavanaugh, Richard
High Energy Physics - Phenomenology
High Energy Physics - Experiment
Data Analysis, Statistics and Probability
Transformer-based models have achieved state-of-the-art performance in jet tagging at the CERN Large Hadron Collider (LHC), with the Particle Transformer (ParT) representing a leading example of such models. A striking feature of ParT is its sparse, nearly binary, attention structure, raising questions about the origin of this behavior and whether it encodes physically meaningful correlations. In this work, we investigate the source of ParT's sparse attention by comparing models trained on multiple benchmark datasets and examine the relative contributions of the attention term and the physics-inspired interaction matrix before softmax. We find that binary sparsity arises primarily from the attention mechanism itself, with the interaction matrix playing a secondary role. Moreove, we show that ParT is able to identify key jet substructure elements, such as leptons in semileptonic top decays, even without explicit particle identification inputs. These results provide new insight into the interpretability of transformer-based jet taggers and clarify the conditions under which sparse attention patterns emerge in ParT.
title Why Is Attention Sparse In Particle Transformer?
topic High Energy Physics - Phenomenology
High Energy Physics - Experiment
Data Analysis, Statistics and Probability
url https://arxiv.org/abs/2512.00210