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Hadron-in-fat-jet AI tagging to detect rare decays such as $W^{\pm} \to π^{\pm} γ$

Linrui Chen ^*, Tianyi Yang^†, Zixun Kou, Zijian Wang, Youpeng Wu, Leyun Gao , and Qiang Li ^‡

School of Physics, Peking University, Beijing, People’s Republic of China

^*Contact author: chenlinrui@whu.edu.cn
^†Contact author: tyyang99@pku.edu.cn
^‡Contact author: qliphy0@pku.edu.cn

Phys. Rev. D 114, 056019 – Published 21 September, 2026

DOI: https://doi.org/10.1103/z3j5-12p5

Abstract

We investigate a novel class of boosted-object signatures at the LHC, where a high- $p_{T}$ fat jet contains an identifiable hadron or quarkonium state originating from rare or semiexclusive decays. Unlike conventional boosted jet studies, which focus on multiprong partonic substructure, our approach probes hybrid configurations such as $W^{\pm} \to π^{\pm} γ$ , where a localized hadronic or quarkonium signal is embedded within a collimated jet. By fine-tuning the signature-oriented, pretrained Sophon artificial intelligence model optimized for large-radius jets, and combining it with an event-level boosted decision tree and a soft-drop-mass shape fit, we obtain an expected 95% confidence level upper limit of $B (W^{\pm} \to π^{\pm} γ) < 2.78 \times 10^{- 5}$ for $450 {fb}^{- 1}$ in our nominal setup. This study serves as a first proof-of-principle demonstration of the hadron-in-fat-jet paradigm; substantial gains in sensitivity are expected from improved trigger strategies, additional production channels, and dedicated taggers, while the methodology itself is broadly applicable to a wide range of rare Standard Model processes and searches for light or exotic resonances at present and future collider experiments.

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Phys. Rev. D 114, 056019– Published 21 September, 2026

Vol. 114, Iss. 5 — 1 September 2026

Received 11 June 2026
Accepted 3 September 2026

DOI: https://doi.org/10.1103/z3j5-12p5

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

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Hadron-in-fat-jet AI tagging to detect rare decays such as $W^{\pm} \to π^{\pm} γ$

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Hadron-in-fat-jet AI tagging to detect rare decays such as W±→π±γ

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References (28)

Hadron-in-fat-jet AI tagging to detect rare decays such as $W^{\pm} \to π^{\pm} γ$