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FAIR Universe Weak Lensing ML Uncertainty Challenge: Handling Uncertainties and Distribution Shifts for Precision Cosmology
Authors:
Biwei Dai,
Po-Wen Chang,
Wahid Bhimji,
Paolo Calafiura,
Ragansu Chakkappai,
Yuan-Tang Chou,
Sascha Diefenbacher,
Jordan Dudley,
Ibrahim Elsharkawy,
Steven Farrell,
Isabelle Guyon,
Chris Harris,
Elham E Khoda,
Benjamin Nachman,
David Rousseau,
Uroš Seljak,
Ihsan Ullah,
Yulei Zhang
Abstract:
Weak gravitational lensing, the correlated distortion of background galaxy shapes by foreground structures, is a powerful probe of the matter distribution in our universe and allows accurate constraints on the cosmological model. In recent years, high-order statistics and machine learning (ML) techniques have been applied to weak lensing data to extract the nonlinear information beyond traditional…
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Weak gravitational lensing, the correlated distortion of background galaxy shapes by foreground structures, is a powerful probe of the matter distribution in our universe and allows accurate constraints on the cosmological model. In recent years, high-order statistics and machine learning (ML) techniques have been applied to weak lensing data to extract the nonlinear information beyond traditional two-point analysis. However, these methods typically rely on cosmological simulations, which poses several challenges: simulations are computationally expensive, limiting most realistic setups to a low training data regime; inaccurate modeling of systematics in the simulations create distribution shifts that can bias cosmological parameter constraints; and varying simulation setups across studies make method comparison difficult. To address these difficulties, we present the first weak lensing benchmark dataset with several realistic systematics and launch the FAIR Universe Weak Lensing Machine Learning Uncertainty Challenge. The challenge focuses on measuring the fundamental properties of the universe from weak lensing data with limited training set and potential distribution shifts, while providing a standardized benchmark for rigorous comparison across methods. Organized in two phases, the challenge will bring together the physics and ML communities to advance the methodologies for handling systematic uncertainties, data efficiency, and distribution shifts in weak lensing analysis with ML, ultimately facilitating the deployment of ML approaches into upcoming weak lensing survey analysis.
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Submitted 15 April, 2026;
originally announced April 2026.
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OmniMol: Transferring Particle Physics Knowledge to Molecular Dynamics with Point-Edge Transformers
Authors:
Ibrahim Elsharkawy,
Vinicius Mikuni,
Wahid Bhimji,
Benjamin Nachman
Abstract:
We present OmniMol, a state-of-the-art all-to-all transformer-based small molecule machine-learned interatomic potential (MLIP). OmniMol is built by adapting Omnilearned, a foundation model for particle jets found in high-energy physics (HEP) experiments such as at the Large Hadron Collider (LHC). Omnilearned is built with a Point-Edge-Transformer (PET) and pre-trained using a diverse set of one b…
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We present OmniMol, a state-of-the-art all-to-all transformer-based small molecule machine-learned interatomic potential (MLIP). OmniMol is built by adapting Omnilearned, a foundation model for particle jets found in high-energy physics (HEP) experiments such as at the Large Hadron Collider (LHC). Omnilearned is built with a Point-Edge-Transformer (PET) and pre-trained using a diverse set of one billion particle jets. It includes an interaction-matrix attention bias that injects pairwise sub-nuclear (HEP) or atomic (molecular-dynamics) physics directly into the transformer's attention logits, steering the network toward physically meaningful neighborhoods without sacrificing expressivity. We demonstrate OmniMol using the oMol dataset and find excellent performance even with relatively few examples for fine-tuning. Further, due to architectural transfer from Omnilearned, we demonstrate uniquely fast inference. This study lays the foundation for building interdisciplinary connections given datasets represented as collections of point clouds.
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Submitted 4 May, 2026; v1 submitted 15 January, 2026;
originally announced January 2026.
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Deep learning the sources of MJO predictability: a spectral view of learned features
Authors:
Lin Yao,
Da Yang,
James P. C. Duncan,
Ashesh Chattopadhyay,
Pedram Hassanzadeh,
Wahid Bhimji,
Bin Yu
Abstract:
The Madden-Julian oscillation (MJO) is a planetary-scale, intraseasonal tropical rainfall phenomenon crucial for global weather and climate; however, its dynamics and predictability remain poorly understood. Here, we leverage deep learning (DL) to investigate the sources of MJO predictability, motivated by a central difference in MJO theories: which spatial scales are essential for driving the MJO…
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The Madden-Julian oscillation (MJO) is a planetary-scale, intraseasonal tropical rainfall phenomenon crucial for global weather and climate; however, its dynamics and predictability remain poorly understood. Here, we leverage deep learning (DL) to investigate the sources of MJO predictability, motivated by a central difference in MJO theories: which spatial scales are essential for driving the MJO? We first develop a deep convolutional neural network (DCNN) to forecast the MJO indices (RMM and ROMI). Our model predicts RMM and ROMI up to 21 and 33 days, respectively, achieving skills comparable to leading subseasonal-to-seasonal models such as NCEP. To identify the spatial scales most relevant for MJO forecasting, we conduct spectral analysis of the latent feature space and find that large-scale patterns dominate the learned signals. Additional experiments show that models using only large-scale signals as the input have the same skills as those using all the scales, supporting the large-scale view of the MJO. Meanwhile, we find that small-scale signals remain informative: surprisingly, models using only small-scale input can still produce skillful forecasts up to 1-2 weeks ahead. We show that this is achieved by reconstructing the large-scale envelope of the small-scale activities, which aligns with the multi-scale view of the MJO. Altogether, our findings support that large-scale patterns--whether directly included or reconstructed--may be the primary source of MJO predictability.
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Submitted 3 October, 2025;
originally announced October 2025.
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FAIR Universe HiggsML Uncertainty Dataset and Competition
Authors:
Lisa Benato,
Wahid Bhimji,
Paolo Calafiura,
Ragansu Chakkappai,
Po-Wen Chang,
Yuan-Tang Chou,
Sascha Diefenbacher,
Jordan Dudley,
Ibrahim Elsharkawy,
Steven Farrell,
Aishik Ghosh,
Cristina Giordano,
Isabelle Guyon,
Chris Harris,
Yota Hashizume,
Shih-Chieh Hsu,
Elham E. Khoda,
Claudius Krause,
Ang Li,
Benjamin Nachman,
Peter Nugent,
David Rousseau,
Robert Schoefbeck,
Maryam Shooshtari,
Dennis Schwarz
, et al. (4 additional authors not shown)
Abstract:
The FAIR Universe HiggsML Uncertainty Challenge focused on measuring the physical properties of elementary particles with imperfect simulators. Participants were required to compute and report confidence intervals for a parameter of interest regarding the Higgs boson while accounting for various systematic (epistemic) uncertainties. The dataset is a tabular dataset of 28 features and 280 million i…
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The FAIR Universe HiggsML Uncertainty Challenge focused on measuring the physical properties of elementary particles with imperfect simulators. Participants were required to compute and report confidence intervals for a parameter of interest regarding the Higgs boson while accounting for various systematic (epistemic) uncertainties. The dataset is a tabular dataset of 28 features and 280 million instances. Each instance represents a simulated proton-proton collision as observed at CERN's Large Hadron Collider in Geneva, Switzerland. The features of these simulations were chosen to capture key characteristics of different types of particles. These include primary attributes, such as the energy and three-dimensional momentum of the particles, as well as derived attributes, which are calculated from the primary ones using domain-specific knowledge. Additionally, a label feature designates each instance's type of proton-proton collision, distinguishing the Higgs boson events of interest from three background sources. As outlined in this paper, the permanent release of the dataset allows long-term benchmarking of new techniques. The leading submissions, including Contrastive Normalising Flows and Density Ratios estimation through classification, are described. Our challenge has brought together the physics and machine learning communities to advance our understanding and methodologies in handling systematic uncertainties within AI techniques.
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Submitted 24 September, 2025; v1 submitted 3 October, 2024;
originally announced October 2024.
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Snowmass 2021 Computational Frontier CompF4 Topical Group Report: Storage and Processing Resource Access
Authors:
W. Bhimji,
D. Carder,
E. Dart,
J. Duarte,
I. Fisk,
R. Gardner,
C. Guok,
B. Jayatilaka,
T. Lehman,
M. Lin,
C. Maltzahn,
S. McKee,
M. S. Neubauer,
O. Rind,
O. Shadura,
N. V. Tran,
P. van Gemmeren,
G. Watts,
B. A. Weaver,
F. Würthwein
Abstract:
Computing plays a significant role in all areas of high energy physics. The Snowmass 2021 CompF4 topical group's scope is facilities R&D, where we consider "facilities" as the computing hardware and software infrastructure inside the data centers plus the networking between data centers, irrespective of who owns them, and what policies are applied for using them. In other words, it includes commer…
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Computing plays a significant role in all areas of high energy physics. The Snowmass 2021 CompF4 topical group's scope is facilities R&D, where we consider "facilities" as the computing hardware and software infrastructure inside the data centers plus the networking between data centers, irrespective of who owns them, and what policies are applied for using them. In other words, it includes commercial clouds, federally funded High Performance Computing (HPC) systems for all of science, and systems funded explicitly for a given experimental or theoretical program. This topical group report summarizes the findings and recommendations for the storage, processing, networking and associated software service infrastructures for future high energy physics research, based on the discussions organized through the Snowmass 2021 community study.
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Submitted 29 September, 2022; v1 submitted 19 September, 2022;
originally announced September 2022.
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Long-term stability and generalization of observationally-constrained stochastic data-driven models for geophysical turbulence
Authors:
Ashesh Chattopadhyay,
Jaideep Pathak,
Ebrahim Nabizadeh,
Wahid Bhimji,
Pedram Hassanzadeh
Abstract:
Recent years have seen a surge in interest in building deep learning-based fully data-driven models for weather prediction. Such deep learning models if trained on observations can mitigate certain biases in current state-of-the-art weather models, some of which stem from inaccurate representation of subgrid-scale processes. However, these data-driven models, being over-parameterized, require a lo…
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Recent years have seen a surge in interest in building deep learning-based fully data-driven models for weather prediction. Such deep learning models if trained on observations can mitigate certain biases in current state-of-the-art weather models, some of which stem from inaccurate representation of subgrid-scale processes. However, these data-driven models, being over-parameterized, require a lot of training data which may not be available from reanalysis (observational data) products. Moreover, an accurate, noise-free, initial condition to start forecasting with a data-driven weather model is not available in realistic scenarios. Finally, deterministic data-driven forecasting models suffer from issues with long-term stability and unphysical climate drift, which makes these data-driven models unsuitable for computing climate statistics. Given these challenges, previous studies have tried to pre-train deep learning-based weather forecasting models on a large amount of imperfect long-term climate model simulations and then re-train them on available observational data. In this paper, we propose a convolutional variational autoencoder-based stochastic data-driven model that is pre-trained on an imperfect climate model simulation from a 2-layer quasi-geostrophic flow and re-trained, using transfer learning, on a small number of noisy observations from a perfect simulation. This re-trained model then performs stochastic forecasting with a noisy initial condition sampled from the perfect simulation. We show that our ensemble-based stochastic data-driven model outperforms a baseline deterministic encoder-decoder-based convolutional model in terms of short-term skills while remaining stable for long-term climate simulations yielding accurate climatology.
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Submitted 9 May, 2022;
originally announced May 2022.
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Software and Computing for Small HEP Experiments
Authors:
Dave Casper,
Maria Elena Monzani,
Benjamin Nachman,
Costas Andreopoulos,
Stephen Bailey,
Deborah Bard,
Wahid Bhimji,
Giuseppe Cerati,
Grigorios Chachamis,
Jacob Daughhetee,
Miriam Diamond,
V. Daniel Elvira,
Alden Fan,
Krzysztof Genser,
Paolo Girotti,
Scott Kravitz,
Robert Kutschke,
Vincent R. Pascuzzi,
Gabriel N. Perdue,
Erica Snider,
Elizabeth Sexton-Kennedy,
Graeme Andrew Stewart,
Matthew Szydagis,
Eric Torrence,
Christopher Tunnell
Abstract:
This white paper briefly summarized key conclusions of the recent US Community Study on the Future of Particle Physics (Snowmass 2021) workshop on Software and Computing for Small High Energy Physics Experiments.
This white paper briefly summarized key conclusions of the recent US Community Study on the Future of Particle Physics (Snowmass 2021) workshop on Software and Computing for Small High Energy Physics Experiments.
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Submitted 27 December, 2022; v1 submitted 15 March, 2022;
originally announced March 2022.
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Optimization of Software on High Performance Computing Platforms for the LUX-ZEPLIN Dark Matter Experiment
Authors:
Venkitesh Ayyar,
Wahid Bhimji,
Maria Elena Monzani,
Andrew Naylor,
Simon Patton,
Craig E. Tull
Abstract:
High Energy Physics experiments like the LUX-ZEPLIN dark matter experiment face unique challenges when running their computation on High Performance Computing resources. In this paper, we describe some strategies to optimize memory usage of simulation codes with the help of profiling tools. We employed this approach and achieved memory reduction of 10-30\%. While this has been performed in the con…
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High Energy Physics experiments like the LUX-ZEPLIN dark matter experiment face unique challenges when running their computation on High Performance Computing resources. In this paper, we describe some strategies to optimize memory usage of simulation codes with the help of profiling tools. We employed this approach and achieved memory reduction of 10-30\%. While this has been performed in the context of the LZ experiment, it has wider applicability to other HEP experimental codes that face these challenges on modern computer architectures.
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Submitted 14 February, 2020;
originally announced February 2020.
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Efficient Probabilistic Inference in the Quest for Physics Beyond the Standard Model
Authors:
Atılım Güneş Baydin,
Lukas Heinrich,
Wahid Bhimji,
Lei Shao,
Saeid Naderiparizi,
Andreas Munk,
Jialin Liu,
Bradley Gram-Hansen,
Gilles Louppe,
Lawrence Meadows,
Philip Torr,
Victor Lee,
Prabhat,
Kyle Cranmer,
Frank Wood
Abstract:
We present a novel probabilistic programming framework that couples directly to existing large-scale simulators through a cross-platform probabilistic execution protocol, which allows general-purpose inference engines to record and control random number draws within simulators in a language-agnostic way. The execution of existing simulators as probabilistic programs enables highly interpretable po…
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We present a novel probabilistic programming framework that couples directly to existing large-scale simulators through a cross-platform probabilistic execution protocol, which allows general-purpose inference engines to record and control random number draws within simulators in a language-agnostic way. The execution of existing simulators as probabilistic programs enables highly interpretable posterior inference in the structured model defined by the simulator code base. We demonstrate the technique in particle physics, on a scientifically accurate simulation of the tau lepton decay, which is a key ingredient in establishing the properties of the Higgs boson. Inference efficiency is achieved via inference compilation where a deep recurrent neural network is trained to parameterize proposal distributions and control the stochastic simulator in a sequential importance sampling scheme, at a fraction of the computational cost of a Markov chain Monte Carlo baseline.
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Submitted 17 February, 2020; v1 submitted 20 July, 2018;
originally announced July 2018.
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Machine Learning in High Energy Physics Community White Paper
Authors:
Kim Albertsson,
Piero Altoe,
Dustin Anderson,
John Anderson,
Michael Andrews,
Juan Pedro Araque Espinosa,
Adam Aurisano,
Laurent Basara,
Adrian Bevan,
Wahid Bhimji,
Daniele Bonacorsi,
Bjorn Burkle,
Paolo Calafiura,
Mario Campanelli,
Louis Capps,
Federico Carminati,
Stefano Carrazza,
Yi-fan Chen,
Taylor Childers,
Yann Coadou,
Elias Coniavitis,
Kyle Cranmer,
Claire David,
Douglas Davis,
Andrea De Simone
, et al. (103 additional authors not shown)
Abstract:
Machine learning has been applied to several problems in particle physics research, beginning with applications to high-level physics analysis in the 1990s and 2000s, followed by an explosion of applications in particle and event identification and reconstruction in the 2010s. In this document we discuss promising future research and development areas for machine learning in particle physics. We d…
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Machine learning has been applied to several problems in particle physics research, beginning with applications to high-level physics analysis in the 1990s and 2000s, followed by an explosion of applications in particle and event identification and reconstruction in the 2010s. In this document we discuss promising future research and development areas for machine learning in particle physics. We detail a roadmap for their implementation, software and hardware resource requirements, collaborative initiatives with the data science community, academia and industry, and training the particle physics community in data science. The main objective of the document is to connect and motivate these areas of research and development with the physics drivers of the High-Luminosity Large Hadron Collider and future neutrino experiments and identify the resource needs for their implementation. Additionally we identify areas where collaboration with external communities will be of great benefit.
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Submitted 16 May, 2019; v1 submitted 8 July, 2018;
originally announced July 2018.
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Improvements to Inference Compilation for Probabilistic Programming in Large-Scale Scientific Simulators
Authors:
Mario Lezcano Casado,
Atilim Gunes Baydin,
David Martinez Rubio,
Tuan Anh Le,
Frank Wood,
Lukas Heinrich,
Gilles Louppe,
Kyle Cranmer,
Karen Ng,
Wahid Bhimji,
Prabhat
Abstract:
We consider the problem of Bayesian inference in the family of probabilistic models implicitly defined by stochastic generative models of data. In scientific fields ranging from population biology to cosmology, low-level mechanistic components are composed to create complex generative models. These models lead to intractable likelihoods and are typically non-differentiable, which poses challenges…
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We consider the problem of Bayesian inference in the family of probabilistic models implicitly defined by stochastic generative models of data. In scientific fields ranging from population biology to cosmology, low-level mechanistic components are composed to create complex generative models. These models lead to intractable likelihoods and are typically non-differentiable, which poses challenges for traditional approaches to inference. We extend previous work in "inference compilation", which combines universal probabilistic programming and deep learning methods, to large-scale scientific simulators, and introduce a C++ based probabilistic programming library called CPProb. We successfully use CPProb to interface with SHERPA, a large code-base used in particle physics. Here we describe the technical innovations realized and planned for this library.
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Submitted 21 December, 2017;
originally announced December 2017.
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A Roadmap for HEP Software and Computing R&D for the 2020s
Authors:
Johannes Albrecht,
Antonio Augusto Alves Jr,
Guilherme Amadio,
Giuseppe Andronico,
Nguyen Anh-Ky,
Laurent Aphecetche,
John Apostolakis,
Makoto Asai,
Luca Atzori,
Marian Babik,
Giuseppe Bagliesi,
Marilena Bandieramonte,
Sunanda Banerjee,
Martin Barisits,
Lothar A. T. Bauerdick,
Stefano Belforte,
Douglas Benjamin,
Catrin Bernius,
Wahid Bhimji,
Riccardo Maria Bianchi,
Ian Bird,
Catherine Biscarat,
Jakob Blomer,
Kenneth Bloom,
Tommaso Boccali
, et al. (285 additional authors not shown)
Abstract:
Particle physics has an ambitious and broad experimental programme for the coming decades. This programme requires large investments in detector hardware, either to build new facilities and experiments, or to upgrade existing ones. Similarly, it requires commensurate investment in the R&D of software to acquire, manage, process, and analyse the shear amounts of data to be recorded. In planning for…
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Particle physics has an ambitious and broad experimental programme for the coming decades. This programme requires large investments in detector hardware, either to build new facilities and experiments, or to upgrade existing ones. Similarly, it requires commensurate investment in the R&D of software to acquire, manage, process, and analyse the shear amounts of data to be recorded. In planning for the HL-LHC in particular, it is critical that all of the collaborating stakeholders agree on the software goals and priorities, and that the efforts complement each other. In this spirit, this white paper describes the R&D activities required to prepare for this software upgrade.
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Submitted 19 December, 2018; v1 submitted 18 December, 2017;
originally announced December 2017.
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Deep Neural Networks for Physics Analysis on low-level whole-detector data at the LHC
Authors:
Wahid Bhimji,
Steven Andrew Farrell,
Thorsten Kurth,
Michela Paganini,
Prabhat,
Evan Racah
Abstract:
There has been considerable recent activity applying deep convolutional neural nets (CNNs) to data from particle physics experiments. Current approaches on ATLAS/CMS have largely focussed on a subset of the calorimeter, and for identifying objects or particular particle types. We explore approaches that use the entire calorimeter, combined with track information, for directly conducting physics an…
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There has been considerable recent activity applying deep convolutional neural nets (CNNs) to data from particle physics experiments. Current approaches on ATLAS/CMS have largely focussed on a subset of the calorimeter, and for identifying objects or particular particle types. We explore approaches that use the entire calorimeter, combined with track information, for directly conducting physics analyses: i.e. classifying events as known-physics background or new-physics signals.
We use an existing RPV-Supersymmetry analysis as a case study and explore CNNs on multi-channel, high-resolution sparse images: applied on GPU and multi-node CPU architectures (including Knights Landing (KNL) Xeon Phi nodes) on the Cori supercomputer at NERSC.
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Submitted 29 November, 2017; v1 submitted 9 November, 2017;
originally announced November 2017.
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Revealing Fundamental Physics from the Daya Bay Neutrino Experiment using Deep Neural Networks
Authors:
Evan Racah,
Seyoon Ko,
Peter Sadowski,
Wahid Bhimji,
Craig Tull,
Sang-Yun Oh,
Pierre Baldi,
Prabhat
Abstract:
Experiments in particle physics produce enormous quantities of data that must be analyzed and interpreted by teams of physicists. This analysis is often exploratory, where scientists are unable to enumerate the possible types of signal prior to performing the experiment. Thus, tools for summarizing, clustering, visualizing and classifying high-dimensional data are essential. In this work, we show…
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Experiments in particle physics produce enormous quantities of data that must be analyzed and interpreted by teams of physicists. This analysis is often exploratory, where scientists are unable to enumerate the possible types of signal prior to performing the experiment. Thus, tools for summarizing, clustering, visualizing and classifying high-dimensional data are essential. In this work, we show that meaningful physical content can be revealed by transforming the raw data into a learned high-level representation using deep neural networks, with measurements taken at the Daya Bay Neutrino Experiment as a case study. We further show how convolutional deep neural networks can provide an effective classification filter with greater than 97% accuracy across different classes of physics events, significantly better than other machine learning approaches.
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Submitted 6 December, 2016; v1 submitted 27 January, 2016;
originally announced January 2016.