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REVIEW 4 major objections 6 minor 130 references

Graph theory inspired anomaly detection at the LHC

T0 review · 4 major / 6 minor · reviewed 2026-08-15 · deepseek-v4-flash

Pith's one-line read A graph autoencoder using 'unique-6' sparse graphs reaches max SIC ≈ 3 on the LHC Olympics benchmark, the best the authors know among unsupervised autoencoders.

desk verdict Solid paper on sparse rigid graphs for jet anomaly detection; central finding is believable, but the state-of-the-art claim and test-set selection need work before I'd trust the headline number. read the letter →

arxiv 2506.19920 v2 pith:WJFRGSAR submitted 2025-06-24 hep-ph hep-exphysics.data-an

classification hep-phhep-exphysics.data-an
keywords anomalydetectiongraphautoencoderrigidityuniquegraphsLamanLHCOlympicsjetsubstructureunsupervisedlearning
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

This paper proposes that the connectivity of a graph representation of a jet can be used as a physics-informed knob for unsupervised new-physics searches, and demonstrates it with a graph autoencoder on the LHC Olympics benchmark. The authors construct sparse graphs with guaranteed geometric rigidity — locally rigid Laman graphs and globally rigid 'unique-k' graphs — and show that a unique-6 graph built from roughly 25 to 30 exclusive kT subjets gives the best anomaly-detection performance, with maximum SIC around 3 and AUC 0.925. They argue that this represents, to their knowledge, the current best result among unsupervised autoencoder-based methods on this data set. The same sparse graphs applied to supervised jet-classification tasks lose only a fraction of a percent of AUC relative to a fully connected model, so the benefit of rigid sparse graphs is specific to the unsupervised setting.

What carries the argument

The key object is the unique-k graph construction. Nodes are particles or subjets ordered by decreasing transverse momentum; the $k+1$ hardest nodes form a fully connected clique, and every later node is joined to its $k$ nearest angular neighbours in the $\eta$--$\phi$ plane. For $k \ge 3$ the result has $|E| = kN - k(k+1)/2$ edges, scales linearly with the number of nodes, and is globally rigid in $\mathbb{R}^2$ because it satisfies Hendrickson's conditions of redundant rigidity and 3-connectivity. The autoencoder consumes node features $p_{T,i}$ and the edge features $\theta_{ij} = (\Delta\eta_{ij}^2 + \Delta\phi_{ij}^2)^{1/2}$, $k_{T,ij} = \min(p_{T,i}, p_{T,j}) \theta_{ij}$, and $z_{ij} = \min(p_{T,i}, p_{T,j})/(p_{T,i}+p_{T,j})$, compresses through a two-dimensional latent node representation, and reconstructs both node and edge features; the per-event sum of the two reconstruction errors is the anomaly score.

What would settle it

On a sample of $10^4$ jets from the LHC Olympics benchmark with $n_{\text{subjets}} = 30$, construct the unique-6 graphs and test each one for redundant rigidity and 3-vertex-connectivity; if a non-negligible fraction fail either condition, the graphs are not globally rigid in the claimed sense.

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Extended reading notes

Core claim

At its core, the paper claims that a globally rigid sparse graph, whose edge lengths fix the positions of all nodes up to overall rotations and translations, is a better input representation for an unsupervised anomaly detector than either a fully connected graph or a merely locally rigid one. With jet constituents ordered by $p_T$, each new node in a unique-$k$ graph is attached to its $k$ nearest neighbours in the $\eta$--$\phi$ plane; for $k \ge 3$ the result is globally rigid in $\mathbb{R}^2$ and still has only $O(N)$ edges. Tested on the LHC Olympics dijet data with $S/B = 3\%$, the graph autoencoder using a unique-6 graph and $n_{\text{subjets}} = 30$ reaches max SIC $\approx 3$ and AUC $= 0.925$, and the paper states that this is, to the best of its authors' knowledge, state-of-the-art among unsupervised autoencoder methods on this benchmark. A control with 'modified Laman' graphs, which add the same number of edges but without the rigidity guarantee, does not reproduce the peak, which the paper takes as evidence that the connectivity structure itself, not merely the number of edges, is responsible.

Load-bearing premise

Everything rests on the claim that connecting each new particle or subjet to its k nearest angular neighbours really does pin down the whole jet geometry uniquely from the edge distances; if realistic jet configurations admitted several different shapes with the same edge lengths, the rigidity argument would not be what produces the performance gain.

Editorial extensions

If this is right

  • At intermediate subjet counts, near $n_{\text{subjets}} \approx 25$--$30$, unsupervised graph autoencoders beat both hadron-level and heavily clustered inputs on the LHC Olympics benchmark; the optimal input is not the most detailed one.
  • The unique-6 connectivity pattern outperforms fully connected graphs of the same subjets, so adding more pairwise distances beyond global rigidity can reduce anomaly-detection sensitivity rather than help it.
  • Global rigidity, not sparsity by itself, is the relevant inductive bias: modified Laman graphs with comparable edge counts do not show the same peak, implying that graph topology should be considered when designing jet representations.
  • The same sparse constructions degrade supervised jet classification by only about 0.3--0.4% AUC relative to a fully connected attention-based classifier while using roughly an order of magnitude fewer pairwise distances.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • If the rigidity mechanism is generic, the unique-k construction should transfer to other anomaly-detection benchmarks and signal topologies; a test across signal variants with different intermediate masses would show whether the $n_{\text{subjets}} \approx 30$ optimum moves with the signal's angular scale.
  • Because the construction breaks permutation invariance by ordering on $p_T$, an extension with random or group-averaged tie-breaking could isolate whether the $p_T$ ordering itself, rather than the rigidity, carries part of the benefit.
  • A sharper falsifiable test would feed the autoencoder randomly rewired graphs with the same degree sequence as unique-6; if the SIC peak survives rewiring, the benefit comes from the degree distribution rather than from global rigidity.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

4 major / 6 minor

Summary. This manuscript develops a graph autoencoder for unsupervised anomaly detection at the LHC, using the LHC Olympics dataset as a benchmark. Jets are represented as graphs built from exclusive kT subjets, with node features given by transverse momenta and edge features by relative angular quantities. Several sparse connectivity structures are compared: locally rigid Laman graphs and globally rigid 'unique-k' graphs, alongside fully connected graphs. The authors report that the best performance occurs at an intermediate number of subjets (nsubjets ~25-30) with the unique-6 graph, giving a maximum SIC of approximately 3 and an AUC of 0.925, and they claim this is the current state-of-the-art among unsupervised autoencoder-based methods on this benchmark. The appendix extends the graph constructions to supervised jet classification tasks (quark vs. gluon, Z vs. QCD, top vs. QCD), finding that sparse graphs can approach the performance of fully connected graphs with far fewer edges. The code is publicly released.

Significance. If the main claims are substantiated, the paper makes a valuable conceptual contribution by linking graph rigidity theory to jet substructure and by demonstrating that sparse, globally rigid graphs can act as effective inductive biases for unsupervised anomaly detection. The empirical finding that performance peaks at an intermediate number of subjets and at an intermediate graph connectivity is interesting and well suited to the LHC Olympics benchmark. The release of the code and the careful description of the architecture are strengths that support reproducibility. The classification appendix is a useful additional result, showing that the graph constructions also illuminate supervised jet tagging. However, the significance is currently tempered by the absence of a direct quantitative comparison to prior autoencoder-based methods and by unresolved questions about the hyperparameter selection protocol for the headline numbers.

major comments (4)
  1. [Sec. 3.3 and Conclusions] The statement that 'to the best of our knowledge, the performance of the unique-6 graph represents the current state-of-the-art among unsupervised autoencoder-based methods for this anomaly detection benchmark data set' is not supported by any quantitative comparison in the manuscript. The text cites Refs. [19,20,24,25,26,27,28,30,31,55] but never tabulates their published maximum SIC or AUC on the same LHC Olympics benchmark. The only comparisons shown are internal variants (absolute node information, fully connected graphs, modified Laman graphs). A reader cannot verify whether the reported max SIC ~3 actually exceeds all prior autoencoder methods. Please add a comparison table with published results from those references, ideally obtained with the same preprocessing and evaluation procedure, or soften the claim to a statement about the methods considered in this paper.
  2. [Sec. 3.1-3.3, Figs. 10 and 12] The manuscript does not state that the hyperparameters (nsubjets=30, unique-6, d_latent=2) were selected on a validation set rather than on the same 5e4 test events used to report the final metrics. Section 3.1 describes a validation set of 1e4 events and a test set of 5e4 events, while Section 3.2 says only that 'a hyperparameter scan showed that d_latent = 2 provides the best performance.' If the scan in Figs. 10 and 12 was evaluated on the test set, then the headline max SIC ~3 is the maximum over a scan of many configurations and is upward-biased by selection. Please clarify the exact protocol, and if the scan was performed on the test set, repeat the evaluation on a truly held-out set for the selected configuration, or apply a multiple-comparison correction and report the expected maximum under the null.
  3. [Sec. 3.2, Eq. (3.2)-(3.3), Fig. 10] The latent representation is per-node with dimension d_latent, so the total latent size scales linearly with the number of subjets N. Varying nsubjets simultaneously changes the physical granularity of the input, the total number of input features (quadratically for fully connected graphs), and the total bottleneck width. The conclusion that anomaly-detection performance peaks at intermediate nsubjets ~25-30 may therefore reflect a capacity or input-dimensionality effect rather than the information content of subjet clustering. Please add a control experiment that keeps the total latent dimension approximately fixed, for example by scaling d_latent with 1/N or by using a graph-level bottleneck, or discuss this confound explicitly.
  4. [Sec. 2.3] The paper asserts that the proposed unique-k construction 'yields a graph that satisfies the Hendrickson conditions for global rigidity,' but no proof is given, and the cited Ref. [70] characterizes globally rigid graphs in general and does not establish that this particular nearest-neighbor addition sequence produces globally rigid graphs. Since the physical interpretation of the performance gain relies on global rigidity, please provide a proof or a precise citation showing that the construction is generically globally rigid for any sequence of nearest-neighbor choices, and ideally verify the 3-connectivity and redundant-rigidity conditions on the actual jet and subjet graphs used in the numerical study, which may contain near-degenerate angular separations.
minor comments (6)
  1. [Fig. 10 caption] The caption states a 'max SIC of 0.294' while the main text and the vertical axis of the figure indicate a value around 3; this inconsistency appears to be a typo and should be corrected.
  2. [Fig. 12 caption] The caption says 'Here the unique-30 graph is fully connected,' but for nsubjets=30 the fully connected graph corresponds to unique-29 under the definition in Sec. 2.3, since a unique-k graph starts from a clique on k+1 nodes. Please correct this inconsistency.
  3. [Sec. 3.1] The manuscript uses S/B = 3% but does not specify how the training, validation, and test samples are constructed from the LHC Olympics data to achieve this signal fraction; please state the exact subsampling procedure.
  4. [Sec. 3.3] The claim that 'comparable performance is observed across a range of values with S/B <= 3%' is not accompanied by a figure or table; please provide the supporting data or remove the claim.
  5. [Appendix A.1] The sentence 'See Refs. for more details [64, 99-127]' appears to have a missing citation marker; please fix the wording.
  6. [References] There are duplicate references in the bibliography: Ref. [83] duplicates [80], Ref. [38] duplicates [81], Ref. [84] duplicates [39], and Ref. [53] duplicates [31]. Please consolidate them.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: graph-construction claims rest on external rigidity theorems and the benchmark is external; the unsupported SOTA comparison is an evidence issue, not a circular one.

full rationale

The paper's derivation chain is empirical and self-contained rather than definitional. The unique-k and Laman constructions are explicit algorithmic definitions (Sec. 2.3) whose rigidity properties are imported from external results by Hendrickson, Connelly, and Gortler et al. (Refs. [70-72]), not from the authors' own prior work. The autoencoder architecture, loss, and anomaly score are defined in Sec. 3.2 without fitting any parameter to the final claim; the maximum SIC and AUC are measured on the external LHC Olympics benchmark. The only noticeable self-citation is Ref. [60] (the authors' earlier subjet-classification paper), used as a consistency remark for the n_subjets ~ 30 peak, and it is not load-bearing for the central unique-6 result. The concerns raised by the skeptic -- that the state-of-the-art claim is not backed by a direct tabulated comparison with prior autoencoder methods, and that hyperparameters (n_subjets, k, d_latent) were selected on the same test benchmark used to report the final metrics -- are real validity or reporting limitations, but they are not cases where a prediction reduces to its input by construction. In particular, no equation in the paper defines the max SIC in terms of n_subjets or k, and no fitted parameter is renamed as a prediction. Under the hard rules requiring an explicit reduction, no circular step is exhibited.

Assumptions & free parameters 3 free parameters · 4 assumptions · 0 invented entities

The ledger contains no new physical entities. The free parameters are benchmark-selected architectural choices, particularly n_subjets and k, which drive the reported optimum. The axioms are standard ML-for-HEP assumptions plus a construction-specific rigidity guarantee that is not independently verified.

free parameters (3)
  • Number of reclustered subjets, n_subjets = 30 (optimal range 25-30)
    Performance peaks at an intermediate number of subjets; this value is selected on the same LHC Olympics benchmark and signal used for evaluation.
  • Graph connectivity order k in unique-k construction = 6 (optimal among tested k values)
    Unique-6 beats unique-3, unique-10, unique-15, Laman, and fully connected graphs on the benchmark; this k is chosen by benchmark performance.
  • Latent dimension d_latent = 2
    A hyperparameter scan selected a two-dimensional latent node representation, creating a tight bottleneck; this is an architecture choice tuned on the target task.
assumptions (4)
  • domain assumption The LHC Olympics R&D dataset, generated with Pythia8 and Delphes without pileup or MPI, is a representative benchmark for LHC anomaly detection.
    All conclusions about model-agnostic LHC searches rest on this fast-simulation dataset; no real collision data, pileup, or multi-parton interactions are used.
  • domain assumption The reconstruction loss of the graph autoencoder is a valid anomaly score for BSM jet signals.
    This is the standard autoencoder anomaly detection assumption; the signal must produce atypical patterns in the chosen pT and relative-angle features. Only one signal topology is tested.
  • ad hoc to paper The k-nearest-neighbor graph construction in Sec. 2.3 produces globally rigid unique graphs satisfying Hendrickson conditions for jet-like point configurations.
    Global rigidity is a known mathematical property, but the specific construction's rigidity guarantee for actual particle and subjet positions is asserted, not verified case by case.
  • domain assumption Relative distances in the rapidity-azimuth plane together with pT capture the jet information needed for anomaly detection.
    The model uses pT as node features and theta_ij, kT_ij, z_ij as edge features, and does not use absolute positions; the paper reports that absolute-position variants perform worse.

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Cite this review

Pith. "Pith review of Graph theory inspired anomaly detection at the LHC." pith.science (2026). https://pith.science/paper/WJFRGSAR

@misc{pith2026250619920,
  author       = {Pith},
  title        = {Pith review of: Graph theory inspired anomaly detection at the LHC},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/WJFRGSAR}},
  note         = {Machine review of arXiv:2506.19920}
}
read the original abstract

Designing model-independent anomaly detection algorithms for analyzing LHC data remains a central challenge in the search for new physics, due to the high dimensionality of collider events. In this work, we develop a graph autoencoder as an unsupervised, model-agnostic tool for anomaly detection, using the LHC Olympics dataset as a benchmark. By representing jet constituents as a graph, we introduce a method to systematically control the information available to the model through sparse graph constructions that serve as physically motivated inductive biases. Specifically, (1) we construct graph autoencoders based on locally rigid Laman graphs and globally rigid unique graphs, and (2) we explore the clustering of jet constituents into subjets to interpolate between high- and low-level input representations. We obtain the best performance, measured in terms of the Significance Improvement Characteristic curve for an intermediate level of subjet clustering and certain sparse unique graph constructions. We further investigate the role of graph connectivity in jet classification tasks. Our results demonstrate the potential of leveraging graph-theoretic insights to refine and increase the interpretability of machine learning tools for collider experiments.

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Reference graph

Works this paper leans on

130 extracted references · 6 canonical work pages

  1. [70]

    Hendrickson,Conditions for unique graph realizations, SIAM Journal on Computing21 (1992), no

    B. Hendrickson,Conditions for unique graph realizations, SIAM Journal on Computing21 (1992), no. 1 65–84, [https://doi.org/10.1137/0221008]

  2. [1]

    Chatrchyan et al.,Observation of a New Boson at a Mass of 125 GeV with the CMS Experiment at the LHC, Phys

    CMS Collaboration, S. Chatrchyan et al.,Observation of a New Boson at a Mass of 125 GeV with the CMS Experiment at the LHC, Phys. Lett. B716 (2012) 30–61, [arXiv:1207.7235]

  3. [2]

    Aad et al.,Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC, Phys

    ATLASCollaboration, G. Aad et al.,Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC, Phys. Lett. B716 (2012) 1–29, [arXiv:1207.7214]

  4. [3]

    CMS Collaboration, T. C. Collaboration et al.,Search for supersymmetry in proton-proton collisions at 13 TeV in final states with jets and missing transverse momentum, JHEP 10 (2019) 244, [arXiv:1908.04722]

  5. [4]

    CMS Collaboration, A. M. Sirunyan et al.,Search for Supersymmetry with a Compressed Mass Spectrum in Events with a Softτ Lepton, a Highly Energetic Jet, and Large Missing Transverse Momentum in Proton-Proton Collisions at√s = TeV, Phys. Rev. Lett.124 (2020), no. 4 041803, [arXiv:1910.01185]

  6. [5]

    ATLASCollaboration, G. Aad et al.,Search for pair production of gluinos decaying via stop and sbottom in events withb-jets and large missing transverse momentum inpp collisions at√s = 13 TeV with the ATLAS detector, Phys. Rev. D94 (2016), no. 3 032003, [arXiv:1605.09318]

  7. [6]

    Khachatryan et al.,Search for supersymmetry in the multijet and missing transverse momentum final state in pp collisions at 13 TeV, Phys

    CMS Collaboration, V. Khachatryan et al.,Search for supersymmetry in the multijet and missing transverse momentum final state in pp collisions at 13 TeV, Phys. Lett. B758 (2016) 152–180, [arXiv:1602.06581]

  8. [7]

    Aaboud et al.,Search for dark matter at√s = 13 TeV in final states containing an energetic photon and large missing transverse momentum with the ATLAS detector, Eur

    ATLASCollaboration, M. Aaboud et al.,Search for dark matter at√s = 13 TeV in final states containing an energetic photon and large missing transverse momentum with the ATLAS detector, Eur. Phys. J. C77 (2017), no. 6 393, [arXiv:1704.03848]

Show all 130 references
  1. [8]

    Aaboud et al.,Search for new phenomena in final states with an energetic jet and large missing transverse momentum inpp collisions at√s = 13 TeV using the ATLAS detector, Phys

    ATLASCollaboration, M. Aaboud et al.,Search for new phenomena in final states with an energetic jet and large missing transverse momentum inpp collisions at√s = 13 TeV using the ATLAS detector, Phys. Rev. D94 (2016), no. 3 032005, [arXiv:1604.07773]

  2. [9]

    Kasieczka et al.,The LHC Olympics 2020 a community challenge for anomaly detection in high energy physics, Rept

    G. Kasieczka et al.,The LHC Olympics 2020 a community challenge for anomaly detection in high energy physics, Rept. Prog. Phys.84 (2021), no. 12 124201, [arXiv:2101.08320]

  3. [10]

    Kasieczka, B

    G. Kasieczka, B. Nachman, and D. Shih,Official datasets for lhc olympics 2020 anomaly detection challenge, Nov., 2019. – 25 –

  4. [11]

    Gambhir, R

    R. Gambhir, R. Mastandrea, B. Nachman, and J. Thaler,Isolating Unisolated Upsilons with Anomaly Detection in CMS Open Data, arXiv:2502.14036

  5. [12]

    Aarrestad et al.,The Dark Machines Anomaly Score Challenge: Benchmark Data and Model Independent Event Classification for the Large Hadron Collider, SciPost Phys.12 (2022), no

    T. Aarrestad et al.,The Dark Machines Anomaly Score Challenge: Benchmark Data and Model Independent Event Classification for the Large Hadron Collider, SciPost Phys.12 (2022), no. 1 043, [arXiv:2105.14027]

  6. [13]

    ATLASCollaboration, G. Aad et al.,Weakly supervised anomaly detection for resonant new physics in the dijet final state using proton-proton collisions at√s = 13 TeV with the ATLAS detector, arXiv:2502.09770

  7. [14]

    Knapp, O

    O. Knapp, O. Cerri, G. Dissertori, T. Q. Nguyen, M. Pierini, and J.-R. Vlimant, Adversarially Learned Anomaly Detection on CMS Open Data: re-discovering the top quark, Eur. Phys. J. Plus136 (2021), no. 2 236, [arXiv:2005.01598]

  8. [15]

    Aad et al.,Search for New Phenomena in Two-Body Invariant Mass Distributions Using Unsupervised Machine Learning for Anomaly Detection at s=13 TeV with the ATLAS Detector, Phys

    ATLASCollaboration, G. Aad et al.,Search for New Phenomena in Two-Body Invariant Mass Distributions Using Unsupervised Machine Learning for Anomaly Detection at s=13 TeV with the ATLAS Detector, Phys. Rev. Lett.132 (2024), no. 8 081801, [arXiv:2307.01612]

  9. [16]

    Bhardwaj, C

    A. Bhardwaj, C. Englert, W. Naskar, V. S. Ngairangbam, and M. Spannowsky,Equivariant, safe and sensitive — graph networks for new physics, JHEP 07 (2024) 245, [arXiv:2402.12449]

  10. [17]

    Belis, P

    V. Belis, P. Odagiu, and T. K. Aarrestad,Machine learning for anomaly detection in particle physics, Rev. Phys.12 (2024) 100091, [arXiv:2312.14190]

  11. [18]

    D. P. Kingma and M. Welling,Auto-Encoding Variational Bayes, arXiv:1312.6114

  12. [19]

    Cerri, T

    O. Cerri, T. Q. Nguyen, M. Pierini, M. Spiropulu, and J.-R. Vlimant,Variational Autoencoders for New Physics Mining at the Large Hadron Collider, JHEP 05 (2019) 036, [arXiv:1811.10276]

  13. [20]

    Cheng, J.-F

    T. Cheng, J.-F. Arguin, J. Leissner-Martin, J. Pilette, and T. Golling,Variational autoencoders for anomalous jet tagging, Phys. Rev. D107 (2023), no. 1 016002, [arXiv:2007.01850]

  14. [21]

    B. M. Dillon, T. Plehn, C. Sauer, and P. Sorrenson,Better Latent Spaces for Better Autoencoders, SciPost Phys.11 (2021) 061, [arXiv:2104.08291]

  15. [22]

    Heimel, G

    T. Heimel, G. Kasieczka, T. Plehn, and J. M. Thompson,QCD or What?, SciPost Phys.6 (2019), no. 3 030, [arXiv:1808.08979]

  16. [23]

    Farina, Y

    M. Farina, Y. Nakai, and D. Shih,Searching for New Physics with Deep Autoencoders, Phys. Rev. D101 (2020), no. 7 075021, [arXiv:1808.08992]

  17. [24]

    S. Tsan, R. Kansal, A. Aportela, D. Diaz, J. Duarte, S. Krishna, F. Mokhtar, J.-R. Vlimant, and M. Pierini,Particle graph autoencoders and differentiable, learned energy mover’s distance, 2021

  18. [25]

    Bortolato, A

    B. Bortolato, A. Smolkovič, B. M. Dillon, and J. F. Kamenik,Bump hunting in latent space, Phys. Rev. D105 (2022), no. 11 115009, [arXiv:2103.06595]

  19. [26]

    Vaslin, V

    L. Vaslin, V. Barra, and J. Donini,GAN-AE: an anomaly detection algorithm for New Physics search in LHC data, Eur. Phys. J. C83 (2023), no. 11 1008, [arXiv:2305.15179]

  20. [27]

    Jawahar, T

    P. Jawahar, T. Aarrestad, N. Chernyavskaya, M. Pierini, K. A. Wozniak, J. Ngadiuba, – 26 – J. Duarte, and S. Tsan,Improving Variational Autoencoders for New Physics Detection at the LHC With Normalizing Flows, Front. Big Data5 (2022) 803685, [arXiv:2110.08508]

  21. [28]

    Finke, M

    T. Finke, M. Krämer, A. Morandini, A. Mück, and I. Oleksiyuk,Autoencoders for unsupervised anomaly detection in high energy physics, JHEP 06 (2021) 161, [arXiv:2104.09051]

  22. [29]

    Laguarta et al.,Detection of anomalies amongst LIGO’s glitch populations with autoencoders, Class

    P. Laguarta et al.,Detection of anomalies amongst LIGO’s glitch populations with autoencoders, Class. Quant. Grav.41 (2024), no. 5 055004, [arXiv:2310.03453]

  23. [30]

    Blance, M

    A. Blance, M. Spannowsky, and P. Waite,Adversarially-trained autoencoders for robust unsupervised new physics searches, JHEP 10 (2019) 047, [arXiv:1905.10384]

  24. [31]

    B. M. Dillon, L. Favaro, T. Plehn, P. Sorrenson, and M. Krämer,A normalized autoencoder for LHC triggers, SciPost Phys. Core6 (2023) 074, [arXiv:2206.14225]

  25. [32]

    Schuhmacher, L

    J. Schuhmacher, L. Boggia, V. Belis, E. Puljak, M. Grossi, M. Pierini, S. Vallecorsa, F. Tacchino, P. Barkoutsos, and I. Tavernelli,Unravelling physics beyond the standard model with classical and quantum anomaly detection, Mach. Learn. Sci. Tech.4 (2023), no. 4 045031, [arXiv...

  26. [33]

    E. M. Metodiev, B. Nachman, and J. Thaler,Classification without labels: Learning from mixed samples in high energy physics, JHEP 10 (2017) 174, [arXiv:1708.02949]

  27. [34]

    L. M. Dery, B. Nachman, F. Rubbo, and A. Schwartzman,Weakly Supervised Classification in High Energy Physics, JHEP 05 (2017) 145, [arXiv:1702.00414]

  28. [35]

    Finke, M

    T. Finke, M. Krämer, M. Lipp, and A. Mück,Boosting mono-jet searches with model-agnostic machine learning, JHEP 08 (2022) 015, [arXiv:2204.11889]

  29. [36]

    J. H. Collins, K. Howe, and B. Nachman,Extending the search for new resonances with machine learning, Phys. Rev. D99 (2019), no. 1 014038, [arXiv:1902.02634]

  30. [37]

    Amram and C

    O. Amram and C. M. Suarez,Tag N’ Train: a technique to train improved classifiers on unlabeled data, JHEP 01 (2021) 153, [arXiv:2002.12376]

  31. [38]

    Andreassen, B

    A. Andreassen, B. Nachman, and D. Shih,Simulation Assisted Likelihood-free Anomaly Detection, Phys. Rev. D101 (2020), no. 9 095004, [arXiv:2001.05001]

  32. [40]

    Buhmann, C

    E. Buhmann, C. Ewen, G. Kasieczka, V. Mikuni, B. Nachman, and D. Shih,Full phase space resonant anomaly detection, Phys. Rev. D109 (2024), no. 5 055015, [arXiv:2310.06897]

  33. [41]

    Hallin, G

    A. Hallin, G. Kasieczka, T. Quadfasel, D. Shih, and M. Sommerhalder,Resonant anomaly detection without background sculpting, Phys. Rev. D107 (2023), no. 11 114012, [arXiv:2210.14924]

  34. [42]

    C. L. Cheng, G. Singh, and B. Nachman,Incorporating physical priors into weakly-supervised anomaly detection, 2025

  35. [43]

    Golling, G

    T. Golling, G. Kasieczka, C. Krause, R. Mastandrea, B. Nachman, J. A. Raine, D. Sengupta, D. Shih, and M. Sommerhalder,The interplay of machine learning-based resonant anomaly detection methods, Eur. Phys. J. C84 (2024), no. 3 241, [arXiv:2307.11157]

  36. [44]

    Golling, S

    T. Golling, S. Klein, R. Mastandrea, and B. Nachman,Flow-enhanced transportation for anomaly detection, Phys. Rev. D107 (2023), no. 9 096025, [arXiv:2212.11285]. – 27 –

  37. [45]

    R. T. d’Agnolo, G. Grosso, M. Pierini, A. Wulzer, and M. Zanetti,Learning new physics from an imperfect machine, Eur. Phys. J. C82 (2022), no. 3 275, [arXiv:2111.13633]

  38. [46]

    J. H. Collins, P. Martín-Ramiro, B. Nachman, and D. Shih,Comparing weak- and unsupervised methods for resonant anomaly detection, Eur. Phys. J. C81 (2021), no. 7 617, [arXiv:2104.02092]

  39. [47]

    Fraser, S

    K. Fraser, S. Homiller, R. K. Mishra, B. Ostdiek, and M. D. Schwartz,Challenges for unsupervised anomaly detection in particle physics, Journal of High Energy Physics2022 (Mar., 2022)

  40. [48]

    van Beekveld, S

    M. van Beekveld, S. Caron, L. Hendriks, P. Jackson, A. Leinweber, S. Otten, R. Patrick, R. R. de Austri, M. Santoni, and M. White,Combining outlier analysis algorithms to identify new physics at the lhc, 2020

  41. [49]

    Caron, L

    S. Caron, L. Hendriks, and R. Verheyen,Rare and different: Anomaly scores from a combination of likelihood and out-of-distribution models to detect new physics at the lhc, SciPost Physics12 (Feb., 2022)

  42. [50]

    J. H. Collins,An exploration of learnt representations of w jets, 2022

  43. [51]

    Mikuni, B

    V. Mikuni, B. Nachman, and D. Shih,Online-compatible unsupervised nonresonant anomaly detection, Phys. Rev. D105 (2022), no. 5 055006, [arXiv:2111.06417]

  44. [52]

    Bradshaw, S

    L. Bradshaw, S. Chang, and B. Ostdiek,Creating simple, interpretable anomaly detectors for new physics in jet substructure, Physical Review D106 (Aug., 2022)

  45. [53]

    B. M. Dillon, L. Favaro, T. Plehn, P. Sorrenson, and M. Krämer,A normalized autoencoder for lhc triggers, 2023

  46. [54]

    Roche, Q

    S. Roche, Q. Bayer, B. Carlson, W. Ouligian, P. Serhiayenka, J. Stelzer, and T. M. Hong, Nanosecond anomaly detection with decision trees and real-time application to exotic Higgs decays, Nature Commun.15 (2024), no. 1 3527, [arXiv:2304.03836]

  47. [55]

    R. Liu, A. Gandrakota, J. Ngadiuba, M. Spiropulu, and J.-R. Vlimant,Fast Particle-based Anomaly Detection Algorithm with Variational Autoencoder, in37th Conference on Neural Information Processing Systems, 11, 2023. arXiv:2311.17162

  48. [56]

    K. Bai, R. Mastandrea, and B. Nachman,Non-resonant anomaly detection with background extrapolation, JHEP 04 (2024) 059, [arXiv:2311.12924]

  49. [57]

    Thaler and K

    J. Thaler and K. Van Tilburg,Identifying Boosted Objects with N-subjettiness, JHEP 03 (2011) 015, [arXiv:1011.2268]

  50. [58]

    I. W. Stewart, F. J. Tackmann, and W. J. Waalewijn,N-Jettiness: An Inclusive Event Shape to Veto Jets, Phys. Rev. Lett.105 (2010) 092002, [arXiv:1004.2489]

  51. [59]

    Catani, Y

    S. Catani, Y. L. Dokshitzer, M. H. Seymour, and B. R. Webber,Longitudinally invariantKt clustering algorithms for hadron hadron collisions, Nucl. Phys. B406 (1993) 187–224

  52. [60]

    Athanasakos, A

    D. Athanasakos, A. J. Larkoski, J. Mulligan, M. Płoskoń, and F. Ringer,Is infrared-collinear safe information all you need for jet classification?, JHEP 07 (2024) 257, [arXiv:2305.08979]

  53. [61]

    Datta and A

    K. Datta and A. Larkoski,How Much Information is in a Jet?, JHEP 06 (2017) 073, [arXiv:1704.08249]

  54. [62]

    Datta and A

    K. Datta and A. J. Larkoski,Novel Jet Observables from Machine Learning, JHEP 03 (2018) 086, [arXiv:1710.01305]. – 28 –

  55. [63]

    Datta, A

    K. Datta, A. Larkoski, and B. Nachman,Automating the Construction of Jet Observables with Machine Learning, Phys. Rev. D100 (2019), no. 9 095016, [arXiv:1902.07180]

  56. [65]

    T. Cai, J. Cheng, N. Craig, G. Koszegi, and A. J. Larkoski,The Phase Space Distance Between Collider Events, arXiv:2405.16698

  57. [66]

    A. J. Larkoski and T. Melia,Covariantizing Phase Space, arXiv:2008.06508

  58. [67]

    Y. S. Lai, J. Mulligan, M. Płoskoń, and F. Ringer,The information content of jet quenching and machine learning assisted observable design, JHEP 10 (2022) 011, [arXiv:2111.14589]

  59. [68]

    Stein, U

    G. Stein, U. Seljak, and B. Dai,Unsupervised in-distribution anomaly detection of new physics through conditional density estimation, in34th Conference on Neural Information Processing Systems, 12, 2020. arXiv:2012.11638

  60. [69]

    Laman,On graphs and rigidity of plane skeletal structures, Journal of Engineering Mathematics 4 (1970), no

    G. Laman,On graphs and rigidity of plane skeletal structures, Journal of Engineering Mathematics 4 (1970), no. 4 331–340

  61. [71]

    Connelly,Generic global rigidity, Discrete & Computational Geometry33 (2005), no

    R. Connelly,Generic global rigidity, Discrete & Computational Geometry33 (2005), no. 4 549–563

  62. [72]

    S. J. Gortler, A. D. Healy, and D. P. Thurston,Characterizing generic global rigidity, American Journal of Mathematics132 (2010), no. 4 897–939

  63. [73]

    Embeddability of weighted graphs in k-space is strongly np-hard, in17th Allerton Conf. Commun. Control Comput., 1979, pp. 480–489, 1979

  64. [74]

    Biswas, H

    P. Biswas, H. Aghajan, and Y. Ye,Semidefinite programming algorithms for sensor network localization using angle information, pp. 220 – 224, 01, 2005

  65. [75]

    Henneberg,Die graphische Statik der starren Systeme

    L. Henneberg,Die graphische Statik der starren Systeme. B.G. Teubners Sammlung von Lehrbüchern auf dem Gebiete der mathematischen Wissenschaften. B. G. Teubner, 1911

  66. [76]

    R. Haas, D. Orden, G. Rote, F. Santos, B. Servatius, H. Servatius, D. Souvaine, I. Streinu, and W. Whiteley,Planar minimally rigid graphs and pseudo-triangulations, Computational Geometry31 (2005), no. 1 31–61. Special Issue on the 19th Annual Symposium on Computational Geomet...

  67. [77]

    Y. L. Dokshitzer, G. D. Leder, S. Moretti, and B. R. Webber,Better jet clustering algorithms, JHEP 08 (1997) 001, [hep-ph/9707323]

  68. [78]

    Wobisch and T

    M. Wobisch and T. Wengler,Hadronization corrections to jet cross-sections in deep inelastic scattering, inWorkshop on Monte Carlo Generators for HERA Physics (Plenary Starting Meeting), pp. 270–279, 4, 1998.hep-ph/9907280

  69. [79]

    Jackson and T

    B. Jackson and T. Jordán,Connected rigidity matroids and unique realizations of graphs, Journal of Combinatorial Theory, Series B94 (2005), no. 1 1–29

  70. [80]

    Nachman and D

    B. Nachman and D. Shih,Anomaly detection with density estimation, Physical Review D101 (Apr., 2020)

  71. [81]

    Andreassen, B

    A. Andreassen, B. Nachman, and D. Shih,Simulation assisted likelihood-free anomaly detection, Physical Review D101 (May, 2020). – 29 –

  72. [82]

    E. M. Metodiev, J. Thaler, and R. Wynne,Anomaly detection in collider physics via factorized observables, 2024

  73. [83]

    Nachman and D

    B. Nachman and D. Shih,Anomaly Detection with Density Estimation, Phys. Rev. D101 (2020) 075042, [arXiv:2001.04990]

  74. [84]

    Hallin, J

    A. Hallin, J. Isaacson, G. Kasieczka, C. Krause, B. Nachman, T. Quadfasel, M. Schlaffer, D. Shih, and M. Sommerhalder,Classifying anomalies through outer density estimation, Phys. Rev. D106 (2022), no. 5 055006, [arXiv:2109.00546]

  75. [85]

    Sjöstrand, S

    T. Sjöstrand, S. Mrenna, and P. Skands,A brief introduction to pythia 8.1, Computer Physics Communications 178 (Jun, 2008) 852–867

  76. [86]

    Selvaggi,DELPHES 3: A modular framework for fast-simulation of generic collider experiments, Journal of Physics: Conference Series523 (jun, 2014) 012033

    M. Selvaggi,DELPHES 3: A modular framework for fast-simulation of generic collider experiments, Journal of Physics: Conference Series523 (jun, 2014) 012033

  77. [87]

    Cacciari, G

    M. Cacciari, G. P. Salam, and G. Soyez,The anti-kt jet clustering algorithm, JHEP 04 (2008) 063, [arXiv:0802.1189]

  78. [88]

    Cacciari, G

    M. Cacciari, G. P. Salam, and G. Soyez,Fastjet user manual, The European Physical Journal C 72 (Mar, 2012)

  79. [89]

    H. Qu, C. Li, and S. Qian,Particle Transformer for Jet Tagging, arXiv:2202.03772

  80. [90]

    Y. Wang, Y. Sun, Z. Liu, S. E. Sarma, M. M. Bronstein, and J. M. Solomon,Dynamic graph cnn for learning on point clouds, ACM Transactions on Graphics (tog)38 (2019), no. 5 1–12

  81. [91]

    K. He, X. Zhang, S. Ren, and J. Sun,Deep residual learning for image recognition, in Proceedings of the IEEE conference on computer vision and pattern recognition, pp. 770–778, 2016

  82. [92]

    Gallicchio, J

    J. Gallicchio, J. Huth, M. Kagan, M. D. Schwartz, K. Black, and B. Tweedie,Multivariate discrimination and the Higgs + W/Z search, JHEP 04 (2011) 069, [arXiv:1010.3698]

  83. [93]

    Ioffe and C

    S. Ioffe and C. Szegedy,Batch normalization: Accelerating deep network training by reducing internal covariate shift, 2015

  84. [94]

    Paszke, S

    A. Paszke, S. Gross, F. Massa, A. Lerer, J. Bradbury, G. Chanan, T. Killeen, Z. Lin, N. Gimelshein, L. Antiga, et al.,Pytorch: An imperative style, high-performance deep learning library, Advances in neural information processing systems32 (2019)

  85. [95]

    D. P. Kingma and J. Ba,Adam: A method for stochastic optimization, arXiv preprint arXiv:1412.6980 (2014)

  86. [96]

    Atkinson, A

    O. Atkinson, A. Bhardwaj, C. Englert, V. S. Ngairangbam, and M. Spannowsky,Anomaly detection with convolutional graph neural networks, Journal of High Energy Physics2021 (Aug., 2021)

  87. [97]

    Batson, C

    J. Batson, C. G. Haaf, Y. Kahn, and D. A. Roberts,Topological Obstructions to Autoencoding, JHEP 04 (2021) 280, [arXiv:2102.08380]

  88. [98]

    V. S. Ngairangbam, B. Rozwoda, K. Sakurai, and M. Spannowsky,Enhancing anomaly detection with topology-aware autoencoders, arXiv:2502.10163

  89. [99]

    Lonnblad, C

    L. Lonnblad, C. Peterson, and T. Rognvaldsson,Finding Gluon Jets With a Neural Trigger, Phys. Rev. Lett.65 (1990) 1321–1324

  90. [100]

    de Oliveira, M

    L. de Oliveira, M. Kagan, L. Mackey, B. Nachman, and A. Schwartzman,Jet-images — deep learning edition, JHEP 07 (2016) 069, [arXiv:1511.05190]. – 30 –

  91. [101]

    P. T. Komiske, E. M. Metodiev, and M. D. Schwartz,Deep learning in color: towards automated quark/gluon jet discrimination, JHEP 01 (2017) 110, [arXiv:1612.01551]

  92. [102]

    Kasieczka, T

    G. Kasieczka, T. Plehn, M. Russell, and T. Schell,Deep-learning Top Taggers or The End of QCD?, JHEP 05 (2017) 006, [arXiv:1701.08784]

  93. [103]

    Louppe, K

    G. Louppe, K. Cho, C. Becot, and K. Cranmer,QCD-Aware Recursive Neural Networks for Jet Physics, JHEP 01 (2019) 057, [arXiv:1702.00748]

  94. [104]

    P. T. Komiske, E. M. Metodiev, and J. Thaler,Energy Flow Networks: Deep Sets for Particle Jets, JHEP 01 (2019) 121, [arXiv:1810.05165]

  95. [105]

    Qu and L

    H. Qu and L. Gouskos,ParticleNet: Jet Tagging via Particle Clouds, Phys. Rev. D101 (2020), no. 5 056019, [arXiv:1902.08570]

  96. [106]

    Kasieczka, S

    G. Kasieczka, S. Marzani, G. Soyez, and G. Stagnitto,Towards Machine Learning Analytics for Jet Substructure, JHEP 09 (2020) 195, [arXiv:2007.04319]

  97. [107]

    F. A. Dreyer and H. Qu,Jet tagging in the Lund plane with graph networks, JHEP 03 (2021) 052, [arXiv:2012.08526]

  98. [108]

    Butter et al.,The Machine Learning landscape of top taggers, SciPost Phys.7 (2019) 014, [arXiv:1902.09914]

    A. Butter et al.,The Machine Learning landscape of top taggers, SciPost Phys.7 (2019) 014, [arXiv:1902.09914]

  99. [109]

    Butter, G

    A. Butter, G. Kasieczka, T. Plehn, and M. Russell,Deep-learned Top Tagging with a Lorentz Layer, SciPost Phys.5 (2018), no. 3 028, [arXiv:1707.08966]

  100. [110]

    Y.-C. J. Chen, C.-W. Chiang, G. Cottin, and D. Shih,BoostedW and Z tagging with jet charge and deep learning, Phys. Rev. D101 (2020), no. 5 053001, [arXiv:1908.08256]

  101. [111]

    J. Y. Araz and M. Spannowsky,Combine and Conquer: Event Reconstruction with Bayesian Ensemble Neural Networks, JHEP 04 (2021) 296, [arXiv:2102.01078]

  102. [112]

    S. Gong, Q. Meng, J. Zhang, H. Qu, C. Li, S. Qian, W. Du, Z.-M. Ma, and T.-Y. Liu,An efficient Lorentz equivariant graph neural network for jet tagging, JHEP 07 (2022) 030, [arXiv:2201.08187]

  103. [113]

    M. D. Schwartz,Modern Machine Learning and Particle Physics, arXiv:2103.12226

  104. [114]

    A. Khot, M. S. Neubauer, and A. Roy,A Detailed Study of Interpretability of Deep Neural Network based Top Taggers, arXiv:2210.04371

  105. [115]

    J. Lin, M. Freytsis, I. Moult, and B. Nachman,BoostingH→b¯b with Machine Learning, JHEP 10 (2018) 101, [arXiv:1807.10768]

  106. [116]

    C. K. Khosa and S. Marzani,Higgs boson tagging with the Lund jet plane, Phys. Rev. D104 (2021), no. 5 055043, [arXiv:2105.03989]

  107. [117]

    Nakai, D

    Y. Nakai, D. Shih, and S. Thomas,Strange Jet Tagging, arXiv:2003.09517

  108. [118]

    Bogatskiy, T

    A. Bogatskiy, T. Hoffman, D. W. Miller, J. T. Offermann, and X. Liu,Explainable equivariant neural networks for particle physics: PELICAN, JHEP 03 (2024) 113, [arXiv:2307.16506]

  109. [119]

    CMS Collaboration, A. M. Sirunyan et al.,Identification of heavy, energetic, hadronically decaying particles using machine-learning techniques, JINST 15 (2020), no. 06 P06005, [arXiv:2004.08262]

  110. [120]

    P. T. Komiske, E. M. Metodiev, and J. Thaler,Energy flow polynomials: A complete linear basis for jet substructure, JHEP 04 (2018) 013, [arXiv:1712.07124]. – 31 –

  111. [121]

    Romero, D

    A. Romero, D. Whiteson, M. Fenton, J. Collado, and P. Baldi,Safety of Quark/Gluon Jet Classification, arXiv:2103.09103

  112. [122]

    Konar, V

    P. Konar, V. S. Ngairangbam, and M. Spannowsky,Energy-weighted Message Passing: an infra-red and collinear safe graph neural network algorithm, arXiv:2109.14636

  113. [123]

    A. J. Larkoski and E. M. Metodiev,A Theory of Quark vs. Gluon Discrimination, JHEP 10 (2019) 014, [arXiv:1906.01639]

  114. [124]

    S. Choi, S. J. Lee, and M. Perelstein,Infrared Safety of a Neural-Net Top Tagging Algorithm, JHEP 02 (2019) 132, [arXiv:1806.01263]

  115. [125]

    Bogatskiy, B

    A. Bogatskiy, B. Anderson, J. T. Offermann, M. Roussi, D. W. Miller, and R. Kondor, Lorentz Group Equivariant Neural Network for Particle Physics, arXiv:2006.04780

  116. [126]

    Esmail, A

    W. Esmail, A. Hammad, and M. Nojiri,IAFormer: Interaction-Aware Transformer network for collider data analysis, arXiv:2505.03258

  117. [127]

    Krause, D

    C. Krause, D. Wang, and R. Winterhalder,BitHEP – The Limits of Low-Precision ML in HEP, arXiv:2504.03387

  118. [128]

    Komiske, E

    P. Komiske, E. Metodiev, and J. Thaler,Pythia8 quark and gluon jets for energy flow, Zenodo (2019)

  119. [129]

    Sjöstrand, S

    T. Sjöstrand, S. Ask, J. R. Christiansen, R. Corke, N. Desai, P. Ilten, S. Mrenna, S. Prestel, C. O. Rasmussen, and P. Z. Skands,An introduction to PYTHIA 8.2, Comput. Phys. Commun. 191 (2015) 159–177, [arXiv:1410.3012]

  120. [130]

    H. Qu, C. Li, and S. Qian,Jetclass: A large-scale dataset for deep learning in jet physics,

  121. [131]

    De Favereau, C

    J. De Favereau, C. Delaere, P. Demin, A. Giammanco, V. Lemaitre, A. Mertens, and M. Selvaggi,Delphes 3: a modular framework for fast simulation of a generic collider experiment, Journal of High Energy Physics2014 (2014), no. 2 1–26

  122. [132]

    C. Ying, T. Cai, S. Luo, S. Zheng, G. Ke, D. He, Y. Shen, and T.-Y. Liu,Do transformers really perform badly for graph representation?, Advances in neural information processing systems 34 (2021) 28877–28888. – 32 –

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