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Publishing statistical models: Getting the most out of particle physics experiments

The statistical models used to derive the results of experimental analyses are of incredible scientific value and are essential information for analysis preservation and reuse. In this paper, we make the scientific case for systematically publishing the full statistical models and discuss the technical developments that make this practical. By means of a variety of physics cases - including parton distribution functions, Higgs boson measurements, effective field theory interpretations, direct searches for new physics, heavy flavor physics, direct dark matter detection, world averages, and beyond the Standard Model global fits - we illustrate how detailed information on the statistical modelling can enhance the short- and long-term impact of experimental results.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Influence of crystal structure on constitutive anisotropy of silica sand at particle-scale

In spite of recent advanced geotechnical research regarding the influence of particle-scale morphology and fabric on the constitutive behavior of silica sands, there is still no published literature that investigated the influence of crystal structure of sand particles on their constitutive behavior. The main constituent of silica sand particles is quartz mineral, which has a trigonal crystal system and hexagonal lattice. This paper investigates the influence of quartz crystal structure on the constitutive response of silica sand particles using 3D X-ray diffraction (3DXRD), synchrotron micro-computed tomography (SMT), and 3D finite element (FE) analysis. Here, unconfined uniaxial compression experiments on single particles of synthetic silica cubes exposed the notion of constitutive anisotropy caused by the crystal structure of quartz. Since the silica cubes have simple regular geometry (1 mm) 3 , they were loaded in different directions with respect to their crystal local planes. The crystal structure was also identified for a natural silica sand specimen composed of 2705 particles and loaded in confined uniaxial compression. Physical limitations of the experimental measurements made a strong case for the use of 3D FE analysis to study how the change in crystal local orientation of individual sand particles can fundamentally produce anisotropy in the constitutive response of natural sand specimens. The 3D FE analysis was validated to accurately model the crystal-based constitutive anisotropy in silica particles using the results of the silica cube experiments. The analysis was then executed on 3D FE meshes that closely matched the physical shape and fabric of the 2705 particles in the natural sand specimen. Both the experiments and 3D FE analysis showed that the crystal structure of quartz essentially causes a directional anisotropy in the constitutive behavior of silica particles.

58 GEOSCIENCES↗

Impacts of Anisotropic Porosity on Heat Transfer and Off-Gassing during Biomass Pyrolysis

The pore structure of biogenic materials imbues the ability to deliver water and nutrients through a plant from root to leaf. This anisotropic pore granularity can also play a significant role in processes such as biomass pyrolysis that are used to convert these materials into useful products like heat, fuel, and chemicals. Evolutions in modeling of biomass pyrolysis as well as imaging of pore structures allow for further insights into the concerted physics of phase change-induced off-gassing, heat transfer, and chemical reactions. In this work, we report a biomass single particle model which incorporates these physics to explore the impact of implementing anisotropic permeability and diffusivity on the conversion time and yields predicted for pyrolysis of oak and pine particles. Simulation results showed that anisotropic permeability impacts predicted conversion time more than 2 times when the Biot number is above 0.1 and pyrolysis numbers (Py 1 , Py 2 ) are less than 20. Pore structure significantly impacts predicted pyrolytic conversion time (>8 times) when the Biot number is above 1 and the pyrolysis number is below 1, i.e., the “conduction controlled” regime. Therefore, these nondimensional numbers reflect that when internal heat conduction limits pyrolysis performance, internal pyrolysis off-gassing further retards effective heat transfer rates as a closely coupled phenomenon. Overall, this study highlights physically meaningful opportunities to improve particle-scale pyrolysis modeling and experimental validation relevant to a variety of feedstock identities and preparations, guiding the future design of pyrolyzers for efficient biomass conversion.

09 BIOMASS FUELS↗

"Experimental Research at the Energy Frontier in High Energy Physics" (Final Technical Report)

Recent developments in particle physics and cosmology raise the exciting prospect that we are on the threshold of a major step forward in our understanding of the universe. This proposal describes a research program at the University of Illinois in experimental high-energy physics on the ATLAS experiment at CERN’s Large Hadron Collider (LHC). Our group actively collaborates with the Theory Group and other experimental efforts within the Office of Science frontiers (energy, intensity, and cosmic) to search broadly in the ATLAS data to maximize our potential for scientifc discovery. The thrust of this proposal is to search for new physics using ATLAS data. Emphasis is placed on novel use of the Higgs boson as a tool to search for new particles and interactions and development of fast particle tracking systems for use in triggering. We propose to continue our strong role in FTK commissioning and operations. To maximize the impact and vitality of the proposed physics program through the HL-LHC running, we will lead firmware efforts in the HWTT Phase-II TDAQ upgrade, leveraging our expertise acquired through development of fast tracking hardware and firmware for the FTK system.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Nuclear Matrix Elements for Neutrinoless Double-Beta Decay from Lattice QCD

Neutrinoless double-beta decay (0vbb) is a hypothetical nuclear decay that is only possible if the neutrino is a Majorana fermion. Experimental searches for this process with ever-increasing sensitivity have placed strong constraints on the 0vbb half-lives of relevant isotopes. Relating these experimental half-lives to the underlying particle physics -- the effective Majorana mass of the neutrino -- requires understanding of the nuclear matrix elements for the transition. These matrix elements can be computed within a nuclear effective field theory framework, but input from lattice QCD is necessary to constrain low-energy constants relevant for the decay. This talk will discuss calculations of these matrix elements using lattice QCD and the implications for determination of nuclear EFT parameters.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Fermilab Report - Fermi National Accelerator Laboratory Monthly Report, June 1979

Fermilab is engaged in several new ventures building for the future of the Laboratory and for excursions into new energy ranges. At the same time, it should be remembered that Fermilab also carries out a vigorous program of particle physics at 400 GeV, or thereabouts, with experimenters from a host of different institutions and a number of different countries. This program, which will be the backbone of Fermilab until the era of TeV physics begins, depends completely on reliable operation of the Fermilab accelerator at the intensities and in the modes needed for experiments. There has not been a review of accelerator operation in these pages since August, 1976, and it seems appropriate to discuss the progress of the accelerator.

Cole, F. T.↗

Overview of the Muon 𝑔 − 2 Experiment at Fermilab

Searching for anomalies is one of the most interesting approaches to physics research. Many particle physicists look for discrepancies between experimental measurements and theoretical predictions because we know that identifying and understanding anomalies can be a major component of building a more fundamental description of nature. The Muon g-2 experiment at Fermilab measures the magnetic anomaly of the muon with extremely high precision. In 2021, the Muon g-2 Collaboration reported its first result at a precision of 460 ppb based on the first data-taking run comprising 6% of the total data set to be collected. This result is in good agreement with the previous measurement from Brookhaven National Laboratory, giving greater certainty to the world average of the experimental value. The next even higher precision Muon g-2 result will play an important role given the recent tensions between data-driven dispersive and lattice QCD calculations to predict the hadronic vacuum polarization contribution. I begin this talk with a review of muon g-2 physics and the experimental technique. Then I present a timeline including the past Run 1 result milestone, current status of Runs 2/3 analysis, and projections to finalize work on the final data from Runs 4/5/6. I conclude with a brief discussion of new ideas and future plans for the Muon g-2 experiment after the completion of Run 6.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Real-Time Artificial Intelligence for Particle Reconstruction and Higgs Physics

With the discovery of the Higgs boson at the CERN LHC, the world's highest-energy particle accelerator complex, scientists have acquired an important tool to study the fundamental building blocks of the universe. Precision measurements of Higgs bosons produced with large momentum allow for unique insights into the structure of the interactions of the Higgs boson with other particles that may shed light on physics beyond the standard model. While experimentally challenging, exploring such interactions with novel artificial intelligence (AI) methods can advance our understanding of the Higgs sector, including the Higgs boson's self-interaction. Moreover, the LHC is undergoing a major upgrade to further increase its particle collision rate and thereby operate for an additional decade. The experimental detectors at the upgraded facility must process at least a factor of ten more data at rates of hundreds of terabytes per second all under challenging conditions. New AI techniques are required to reconstruct and select, or trigger on, the most physics-sensitive events in real-time to handle the resulting avalanche of data. The proposed research will achieve the goals of the LHC program at the CMS experiment by developing a sub-microsecond event reconstruction system using real-time AI algorithms that employ field-programmable gate array technologies. By harnessing sophisticated AI techniques, this research focuses on measuring the production of Higgs bosons at large momentum while enhancing particle reconstruction methods in the trigger and beyond. Overall, the proposed research has broader implications for the use of AI in resource-constrained, low-latency embedded applications across all fields of science.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Charged Lepton Flavour Violations searches with muons: present and future

Charged-lepton flavor violation (cLFV) is one of the most powerful probes for New Physics (NP). Since lepton flavor conservation is an accidental symmetry in the Standard Model (SM), it is naturally violated in many NP models, with contributions at the level of the current experimental sensitivities. Moreover, the negligible SM contributions would make the observation of cLFV unambiguous evidence of NP. It makes these searches extremely sensitive and, at the same time, extremely pure. Thanks to the intense muon beams currently available, their intriguing upgrade programs, and the progress in the detection techniques, cLFV muon processes are the golden channels in this field. Experimental programs to search for $\mu^+ \to e^+ \gamma$, $\mu^+ \to e^+ e^+ e^-$ and the $\mu \to e$ conversion in the nuclear field are currently ongoing. We review the current status and the strategic plans for future searches. This document is an update of the prior cLFV submission to the 2018 European Strategy for Particle Physics (ESPP); the earlier submission should be consulted for more experimental details.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

A Numerical Simulation of a Single Shock-Accelerated Particle

Particle drag models, which capture macro viscous and pressure effects, have been developed over the years for various flow regimes to enable cost effective simulations of particle-laden flows. The relatively recent derivation by Maxey and Riley has provided an exact equation of motion for spherical particles in a flow field based on the continuum assumption. Many models that have been simplified from these equations have provided reasonable approximations; however, the sensitivity of particle-laden flows to particle drag requires a very accurate model to simulate. To develop such a model, a 2D axisymmetric Navier-Stokes direct numerical simulation of a single particle in a transient, shock-driven flow field was conducted in the hydrocode FLAG. FLAG’s capability to run arbitrary Lagrangian-Eulerian hydrodynamics coupled with solid mechanic models makes it an ideal code to capture the physics of the flow field around and in the particle as it is shock-accelerated – a challenging regime to study. The goal of this work is twofold: to provide a validation for FLAG’s Navier-Stokes and heat diffusion solutions, and to provide a rationale for recent experimental particle drag measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Hydrogen Diffusion Through Stainless Steel

SAND2025-14430O Hydrogen Diffusion Through Stainless Steel is a tool that employs a finite difference method algorithm to solve Fick's law and other mass transport models pertinent to the diffusion of hydrogen through stainless steel. Additionally, the software uses particle swarm optimization to determine physical parameters based on experimental data. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Mason, Tyler [Sandia National Lab. (SNL-CA), Liver↗

A practical guide to unbinned unfolding

Unfolding, in the context of high-energy particle physics, refers to the process of removing detector distortions in experimental data. The resulting unfolded measurements are straightforward to use for direct comparisons between experiments and a wide variety of theoretical predictions. For decades, popular unfolding strategies were designed to operate on data formatted as one or more binned histograms. In recent years, new strategies have emerged that use machine learning to unfold datasets in an unbinned manner, allowing for higher-dimensional analyses and more flexibility for current and future users of the unfolded data. This guide comprises recommendations and practical considerations from researchers across a number of major particle physics experiments who have recently put these techniques into practice on real data.

Canelli, Florencia [Univ. of Zurich (Switzerland)]↗

Probing the Neutrino-Mass Scale with the KATRIN Experiment

The absolute mass scale of neutrinos is an intriguing open question in contemporary physics. The as-yet-unknown mass of the lightest and, at the same time, most abundant massive elementary particle species bears fundamental relevance to theoretical particle physics, astrophysics, and cosmology. The most model-independent experimental approach consists of precision measurements of the kinematics of weak decays, notably tritium β decay. With the KATRIN experiment, this direct neutrino-mass measurement has entered the sub-eV domain, recently pushing the upper limit on the electron-based neutrino mass down to 0.8 eV (90% CL) on the basis of first-year data out of ongoing, multiyear operations. Here, we review the experimental apparatus of KATRIN, the progress of data taking, and initial results. While KATRIN is heading toward the target sensitivity of 0.2 eV, other scientific goals are pursued. We discuss the search for light sterile neutrinos and an outlook on future keV-scale sterile-neutrino searches as well as further physics opportunities beyond the Standard Model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

The Next Breakthroughs in Neutrino Physics (LDRD Final Report)

The neutrino is an important fundamental particle, one of the building blocks of the universe. Abetter understanding of the neutrino will answer questions regarding the origin of mass, the matter and anti-matter asymmetry of the universe, and the nature of dark matter. The nation's research community has recognized that the answers to these and other questions are within reach and has assigned neutrino experiments the highest priority for both nuclear and particle physics programs. We are investigating three aspects of neutrino experimentation: detection techniques, target materials, and data analysis. Our efforts targeted multiple applications including experiments to measure neutrinoless double-beta-decay, neutrino-oscillation and neutrino mass. Our research objectives include (1) developing approaches that make detectors scalable to larger sizes and insensitive to background signals; (2) increasing the signal strength and reducing noise from targets; and (3) efficiently distinguishing background noise from signals during analysis. In this LDRD we have advanced all of these areas. We have demonstrated the scale up of a metal organic framework that can adsorb xenon directly from the air that will allow for large neutrino detectors made from xenon. We have studied the use of Cherenkov radiation to reduce the signal backgrounds. We demonstrated the cracking of hydrogen to make atomic tritium for neutrino mass measurements, and lastly we demonstrated the benefits of machine learning techniques to improve signal to noise during analysis

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Ghost particles and Project Poltergeist: Long-ago Lab physicists studied science that haunted them

A neutrino is a tiny, almost massless particle that travels at near light speeds. They were first formed in the early universe and are continually being produced in the nuclear reactions of stars, like the sun, and nuclear reactions on earth. The existence of these “ghost particles” was incredibly difficult to detect, but doing so has helped scientists better understand fundamental principles in physics. Los Alamos Manhattan Project scientist Frederick Reines, along with his colleague Clyde Cowan, is credited with the experimental discovery of the nearly massless elementary particle after his team definitively proved the neutrino’s existence in 1956. Reines received the Nobel Prize in Physics in 1995.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Ghost particles and Project Poltergeist: Long-ago Lab physicists studied science that haunted them

A neutrino is a tiny, almost massless particle that travels at near light speeds. They were first formed in the early universe and are continually being produced in the nuclear reactions of stars, like the sun, and nuclear reactions on earth. The existence of these “ghost particles” was incredibly difficult to detect, but doing so has helped scientists better understand fundamental principles in physics. Los Alamos Manhattan Project scientist Frederick Reines, along with his colleague Clyde Cowan, is credited with the experimental discovery of the nearly massless elementary particle after his team definitively proved the neutrino’s existence in 1956. Reines received the Nobel Prize in Physics in 1995.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Future Circular Collider Feasibility Study Report

Volume 1 of the FCC Feasibility Report presents an overview of the physics case, experimental programme, and detector concepts for the Future Circular Collider (FCC). This volume outlines how FCC would address some of the most profound open questions in particle physics, from precision studies of the Higgs and EW bosons and of the top quark, to the exploration of physics beyond the Standard Model. The report reviews the experimental opportunities offered by the staged implementation of FCC, beginning with an electron-positron collider (FCC-ee), operating at several centre-of-mass energies, followed by a hadron collider (FCC-hh). Benchmark examples are given of the expected physics performance, in terms of precision and sensitivity to new phenomena, of each collider stage. Detector requirements and conceptual designs for FCC-ee experiments are discussed, as are the specific demands that the physics programme imposes on the accelerator in the domains of the calibration of the collision energy, and the interface region between the accelerator and the detector. The report also highlights advances in detector, software and computing technologies, as well as the theoretical tools/reconstruction techniques that will enable the precision measurements and discovery potential of the FCC experimental programme. The content and structure of this report are guided by the scope and priorities defined in the mandate of the FCC Feasibility Study. It is therefore not intended to serve as an exhaustive review of the full physics potential of FCC. Several topics, already covered in earlier reports such as the FCC CDR, are not reiterated here or are addressed only briefly, in alignment with the study’s focus. This volume reflects the outcome of a global collaborative effort involving hundreds of scientists and institutions, aided by a dedicated community-building coordination, and provides a targeted assessment of the scientific opportunities and experimental foundations of the FCC programme.

Benedikt, M. [European Organization for Nuclear Re↗

Toward an event-level analysis of hadron structure using differential programming

Reconstructing the internal properties of hadrons in terms of fundamental quark and gluon de- grees of freedom is a central goal in nuclear and particle physics. This effort lies at the core of major experimental programs, such as the Jefferson Lab 12 GeV program and the upcoming Electron-Ion Collider. A primary challenge is the inherent inverse problem: converting large-scale observational data from collision events into the fundamental QCD-defined densities that characterize the micro- scopic structure of hadronic systems. Recent advances in AI and machine learning have opened new avenues for addressing this challenge using deep learning techniques. A particularly promising direction is the integration of complex theoretical calculations and experimental simulations into a unified framework capable of reconstructing these densities directly from event-level information. In this document, we introduce a key algorithm called LOITS, which enables differentiable program- ming within such a framework, facilitating the use of AI/ML techniques to solve the inverse problem of QCF reconstruction at the event level.

Braga, Kevin [College of William and Mary, William↗