arXiv subjects

Callum Wilkinson

Publications and source records attributed to Callum Wilkinson.

At least 19 recordsLinked to original sources

arXiv2026

CP-violation or Nuclear Excitation: Reviewing the Role of Neutrino Interaction Model Uncertainties on Accelerator-Based Neutrino Oscillation Measurements

Accelerator-based neutrino oscillation experiments have the potential to revolutionise our understanding of fundamental physics, offering an opportunity to characterise charge-parity violation in the lepton sector; to determine the neutrino mass ordering; and to explore the possibility of physics beyond three-flavour neutrino mixing. However, as more data is collected, the current and next-generation of experiments will require increasingly precise control over the systematic uncertainties within their analyses. It is well known that some of the most challenging uncertainties to overcome stem from our uncertain modelling of neutrino--nucleus interactions, which also affect the event rates used to infer the oscillation probability. The sources of these uncertainties are often related to subtle details of the pertinent nuclear physics which are extremely difficult to control with sufficient precision. Confronting such uncertainties requires both state-of-the-art theoretical modelling and precise measurements of neutrino interaction event rates at experiment's near detectors, before oscillations occur. In this work, we review the role of neutrino interaction systematic uncertainties in current and future measurements of neutrino oscillation as well as the experimental and theoretical prospects for reducing them to an acceptable level for the next generation of experiments.

hep-ex↗

arXiv2026

Cross-Domain Transfer with Particle Physics Foundation Models: From Jets to Neutrino Interactions

Future AI-based studies in particle physics will likely start from a foundation model to accelerate training and enhance sensitivity. As a step toward a general-purpose foundation model for particle physics, we investigate whether the OmniLearned and ParticleViT foundation models pretrained on diverse high-$Q^2$ simulated and real $pp$ and $ep$ collisions retain useful knowledge to a few-GeV fixed-target neutrino experiment. We process MINERvA neutrino--nucleus scattering events and evaluate pretrained models on two types of tasks: regression of available energy and binary classification of charged-current pion final states ($\mathrm{CC1\pi^{\pm}}$, $\mathrm{CCN\pi^{\pm}}$, and $\mathrm{CC1\pi^{0}}$). Pretrained OmniLearned and ParticleViT models outperform similarly sized models trained from scratch at the same compute budget, with the largest gains for OmniLearned on regression and for ParticleViT on classification. When the same transformer architecture is instead initialized from unrelated text pretraining (BERT), this advantage appears only marginally for classification in terms of compute efficiency and not in any way for regression. These results suggest that particle-level foundation models acquire inductive biases that generalize across large differences in energy scale, detector technology, and underlying physics processes, pointing toward detector-agnostic inference in particle physics.

hep-ex↗

arXiv2025

Machine Learning-Assisted Unfolding for Neutrino Cross-section Measurements with the OmniFold Technique

The choice of unfolding method for a cross-section measurement is tightly coupled to the model dependence of the efficiency correction and the overall impact of cross-section modeling uncertainties in the analysis. A key issue is the dimensionality used in unfolding, as the kinematics of all outgoing particles in an event typically affect the reconstruction performance in a neutrino detector. OmniFold is an unfolding method that iteratively reweights a simulated dataset, using machine learning to utilize arbitrarily high-dimensional information, that has previously been applied to proton-proton and proton-electron datasets. This paper demonstrates OmniFold's application to a neutrino cross-section measurement for the first time using a public T2K near detector simulated dataset, comparing its performance with traditional approaches using a mock data study.

physics.data-an↗

arXiv2023

A tolerable candle: the low-$\nu$ method with LHC neutrinos

The Forward Physics Facility (FPF) plans to use neutrinos produced at the Large Hadron Collider (LHC) to make a variety of measurements at previously unexplored TeV energies. Its primary goals include precision measurements of the neutrino cross section and using the measured neutrino flux both to uncover information about far-forward hadron production and to search for various beyond standard model scenarios. However, these goals have the potential to conflict: extracting information about the flux or cross section relies upon an assumption about the other. In this manuscript, we demonstrate that the FPF can use the low-$\nu$ method -- a technique for constraining the flux shape by isolating neutrino interactions with low energy transfer to the nucleus -- to break this degeneracy. We show that the low-$\nu$ method is effective for extracting the $\nu_{\mu}$ flux shape, in a model-independent way. We discuss its application for extracting the $\bar{\nu}_{\mu}$ flux shape, but find that this is significantly more model dependent. Finally, we explore the precision to which the $\nu_{\mu}$ flux shape could be constrained at the FPF, for a variety of proposed detector options. We find that the precision would be sufficient to discriminate between various realistic flux models.

hep-ph↗

arXiv2022

A substandard candle: the low-$\nu$ method at few-GeV neutrino energies

As accelerator-neutrino oscillation experiments improve oscillation parameter constraints, control over systematic uncertainties on the incoming neutrino flux and interaction models is increasingly important. The intense beams offered by modern experiments permit a variety of options to constrain the flux using in situ "standard candle" measurements. These standard candles must use very well understood processes to avoid introducing bias. One option discussed in this context is the "low-$\nu$" method, designed to isolate neutrino interactions where there is low energy-transfer to the nucleus, such that the cross section is expected to be approximately constant as a function of neutrino energy. The shape of the low-energy transfer event sample can then be used to extract the flux shape. Applications of the method at high neutrino energies (many tens of GeV) are well understood. However, the applicability of the method at the few-GeV energies of current and future accelerator neutrino experiments remains unclear due to the presence of nuclear and form-factor effects. In this analysis we examine the prospects for improving constraints on accelerator neutrino fluxes with the low-$\nu$ method in an experiment-independent way, using (anti)neutrino interactions on argon and hydrocarbon targets from the GENIE, NEUT, NuWro and GiBUU event generators. The results show that flux constraints from the low-$\nu$ method would be severely dependent on the specific interaction model assumptions used in an analysis for neutrino energies less than 5 GeV. The spread of model predictions show that a low-$\nu$ analysis is unlikely to offer much improvement on typical neutrino flux uncertainties, even with a perfect detector. Notably -- running counter to the assumption inherent to the low-$\nu$ method -- the model-dependence increases with decreasing energy transfer for experiments in the few-GeV region.

hep-ph↗

arXiv2022

Neutrino Scattering Measurements on Hydrogen and Deuterium: A Snowmass White Paper

Neutrino interaction uncertainties are a limiting factor in current and next-generation experiments probing the fundamental physics of neutrinos, a unique window on physics beyond the Standard Model. Neutrino-nucleon scattering amplitudes are an important part of the neutrino interaction program. However, since all modern neutrino detectors are composed primarily of heavy nuclei, knowledge of elementary neutrino-nucleon amplitudes relies heavily on experiments performed in the 1970s and 1980s, whose statistical and systematic precision are insufficient for current needs. In this white paper, we outline the motivation for attempting measurements on hydrogen and deuterium that would improve this knowledge, and we discuss options for making these measurements either with the DUNE near detector or with a dedicated facility.

hep-ex↗

arXiv2022

Bubble Chamber Detectors with Light Nuclear Targets: A Snowmass 2021 White Paper

Neutrino cross sections are a critical ingredient in experiments that depend on neutrino scattering to reconstruct event kinematics and infer neutrino characteristics, like NOvA and T2K. An opportunity exists to reduce the 5-10% broad uncertainty on neutrino cross sections by producing more measurements of neutrino scattering from light nuclear targets at the relevant energies. Bubble chambers with light nuclear targets would be ideal for these measurements but the most recent device designed for use with an accelerator neutrino source is at least fifty years old. A new bubble chamber with light nuclear targets could be designed by observing how the technology has progressed for use in dark matter experiments and producing smaller modular devices that use more efficient cooling systems. A smaller modular device could also be designed for deployment to all functioning neutrino beams, but an investigation of the proper operating characteristics is necessary to adapt newer detectors to the structure of contemporary neutrino beams.

physics.ins-det↗

arXiv2022

Status of Lattice QCD Determination of Nucleon Form Factors and their Relevance for the Few-GeV Neutrino Program

Calculations of neutrino-nucleus cross sections begin with the neutrino-nucleon interaction, making the latter critically important to flagship neutrino oscillation experiments, despite limited measurements with poor statistics. Alternatively, lattice QCD (LQCD) can be used to determine these interactions from the Standard Model with quantifiable theoretical uncertainties. Recent LQCD results of $g_{\mathrm{A}}$ are in excellent agreement with data, and results for the (quasi-)elastic nucleon form factors with full uncertainty budgets are expected within a few years. We review the status of the field and LQCD results for the nucleon axial form factor, $F_{\mathrm{A}}(Q^2)$, a major source of uncertainty in modeling sub-GeV neutrino-nucleon interactions. Results from different LQCD calculations are consistent, but collectively disagree with existing models, with potential implications for current and future neutrino oscillation experiments. We describe a road map to solidify confidence in the LQCD results and discuss future calculations of more complicated processes, important to few-GeV neutrino oscillation experiments.

hep-lat↗

arXiv2019

Neutrino-electron elastic scattering for flux determination at the DUNE oscillation experiment

We study the feasibility of using neutrino-electron elastic scattering to measure the neutrino flux in the DUNE neutrino oscillation experiment. The neutrino-electron scattering cross section is precisely known, and the kinematics of the reaction allow determination of the incoming neutrino energy by precise measurement of the energy and angle of the recoiling electron. For several possible near detectors, we perform an analysis of their ability to measure neutrino flux in the presence of backgrounds and uncertainties. With realistic assumptions about detector masses, we find that a liquid argon detector, even with limitations due to angular resolution, is able to perform better than less dense detectors with more precise event-by-event neutrino energy measurements. We find that the absolute flux normalization uncertainty can be reduced from ~8% to ~2%, and the uncertainty on the flux shape can be reduced by ~20-30%.

hep-ex↗

arXiv2019

Detecting and Studying High-Energy Collider Neutrinos with FASER at the LHC

Neutrinos are copiously produced at particle colliders, but no collider neutrino has ever been detected. Colliders, and particularly hadron colliders, produce both neutrinos and anti-neutrinos of all flavors at very high energies, and they are therefore highly complementary to those from other sources. FASER, the recently approved Forward Search Experiment at the Large Hadron Collider, is ideally located to provide the first detection and study of collider neutrinos. We investigate the prospects for neutrino studies of a proposed component of FASER, FASER$\nu$, a 25cm x 25cm x 1.35m emulsion detector to be placed directly in front of the FASER spectrometer in tunnel TI12. FASER$\nu$ consists of 1000 layers of emulsion films interleaved with 1-mm-thick tungsten plates, with a total tungsten target mass of 1.2 tons. We estimate the neutrino fluxes and interaction rates at FASER$\nu$, describe the FASER$\nu$ detector, and analyze the characteristics of the signals and primary backgrounds. For an integrated luminosity of 150 fb$^{-1}$ to be collected during Run 3 of the 14 TeV Large Hadron Collider from 2021-23, and assuming standard model cross sections, approximately 1300 electron neutrinos, 20,000 muon neutrinos, and 20 tau neutrinos will interact in FASER$\nu$, with mean energies of 600 GeV to 1 TeV, depending on the flavor. With such rates and energies, FASER will measure neutrino cross sections at energies where they are currently unconstrained, will bound models of forward particle production, and could open a new window on physics beyond the standard model.

hep-ex↗

arXiv2019

Measurements of neutrino-nucleus scattering

Current and planned neutrino oscillation experiments operate in the 0.1-10 GeV energy regime. At these energies, the neutrino cross section is not well understood: a variety of interaction processes are possible and nuclear effects play a significant role. Here, the conceptual problems that affect measuring and understanding neutrino cross sections are introduced, and the status of neutrino cross section measurements for CC0$\pi$ and CC1$\pi$ channels are discussed.

hep-ex↗

arXiv2018

PhyStat-$\nu$ 2016 at the IPMU: Summary of Discussions

The presentations, discussions and findings from the inaugural `PhyStat-$\nu$' workshop held at the Kavli Institute for the Physics and Mathematics of the Universe (IPMU) near Tokyo in 2016 are described. PhyStat-$\nu$ was the first workshop to focus solely on statistical issues across the broad range of modern neutrino physics, bringing together physicists who are active in the analysis of neutrino data with experts in statistics to explore statistical issues in the field. It is a goal of PhyStat-$\nu$ to help serve the neutrino physics community by providing a forum within which such statistical issues can be discussed and disseminated broadly. This paper is adapted from a summary document that was initially circulated amongst the participants soon after the workshop. Another PhyStat-$\nu$ workshop is being held at CERN in January 2019, building on the discussions in 2016. Advances in experimental neutrino physics in recent years have led to much larger datasets and more diversity in the properties of neutrinos that are being investigated. The discussions here raised several areas where improved statistical errors and more complicated interpretations of the data require statistical methods to be revisited, as well as topics where broader discussions between experimentalists, phenomenologists and theorists will required, which are summarised here. It is important to record the state of the field as it stands today, as much is expected to change over the coming years, including the emergence of more inter-collaborational studies and increasing sophistication in global parameter fitting and model selection methods. The document is also intended to serve as a reference for pedagogical material for those who are new to the use of modern statistical techniques to describe experimental data, as well as those who are well-versed in these techniques and wish to apply them to new data.

hep-ex↗

arXiv2018

Progress in measurements of 0.1--10 GeV neutrino-nucleus scattering and anticipated results from future experiments

Neutrino interactions with nuclei have been the subject of intense interest over the last 15 years. Current and future measurements of neutrino oscillation and exotic physics use order 0.1--10 GeV neutrinos on a range of nuclear targets ($^{12}$C, $^{16}$O, $^{40}$Ar). As the precision of these experiments has increased, information from their detectors and dedicated experiments indicate deficiencies in the modeling of neutrino interactions on nuclear targets. Here, we present the current state of knowledge about neutrino-nucleus interactions, the challenge of extracting the cross section of these processes, and current experimental puzzles in the field. We also look forward to new and novel measurements and efforts in the future which seek to resolve these questions.

hep-ex↗

arXiv2016

Direct extraction of nuclear effects in quasielastic scattering on carbon

Nuclear effects on neutrino reactions are expected to be a significant complication in current and future neutrino oscillation experiments seeking precision measurements of neutrino flavor transitions. Calculations of these nuclear effects are hampered by a lack of experimental data comparing neutrino reactions on free nucleons to neutrino reactions on nuclei. We present results from a novel technique that compares neutrino and antineutrino charged current quasielastic scattering on hydrocarbons to extract a cross section ratio of antineutrino charged current elastic reactions on free protons to charged current quasielastic reactions on the protons bound in a carbon nucleus. This measurement of nuclear effects is compared to models.

hep-ex↗

arXiv2016

Constraining the GENIE model of neutrino-induced single pion production using reanalyzed bubble chamber data

The longstanding discrepancy between bubble chamber measurements of $\nu_\mu$-induced single pion production channels has led to large uncertainties in pion production cross section parameters for many years. We extend the reanalysis of pion production data in deuterium bubble chambers where this discrepancy is solved (Wilkinson et al., PRD 90 (2014) 112017) to include the $\nu_{\mu}n\rightarrow \mu^{-}p\pi^{0}$ and $\nu_{\mu}n\rightarrow \mu^{-}n\pi^{+}$ channels, and use the resulting data to fit the parameters of the GENIE (Rein-Sehgal) pion production model. We find a set of parameters that can describe the bubble chamber data better than the GENIE default parameters, and provide updated central values and reduced uncertainties for use in neutrino oscillation and cross section analyses which use the GENIE model. We find that GENIE's non-resonant background prediction has to be significantly reduced to fit the data, which may help to explain the recent discrepancies between simulation and data observed by the MINERvA coherent pion and NOvA oscillation analyses.

hep-ex↗

arXiv2015

NEUT development for T2K and relevance of updated 2p2h models

The MiniBooNE large axial-mass anomaly has motivated the development of new theoretical Charged Current Quasi-Elastic (CCQE) cross-section models in recent years. These proceedings review the development of the neutrino simulation generator NEUT to incorporate these more sophisticated CCQE models, including multi-nucleon interaction (2p2h) effects. The fit results on the MINER$\nu$A and MiniBoone data are used to tune neutrino interaction models in NEUT and develop a default cross-section model for T2K.

hep-ex↗

arXiv2015

Effect of cross-section models on the validity of sterile neutrino mixing limits

Charged-Current Quasi-Elastic (CCQE) neutrino scattering is the signal channel for sterile neutrino oscillation experiments. Recent cross-section measurements have made it clear that the current understanding of this channel in the few-GeV region is incomplete, and several sophisticated theoretical models have been proposed to tackle this issue, although it is not clear which model best describes the global dataset. In this paper we argue that the current uncertainty surrounding CCQE cross-sections is a serious problem for experiments seeking to produce sterile neutrino limits. We perform a sterile neutrino analysis with published MINERvA data as an illustrative example. We highlight the need for caution in interpreting sterile neutrino limits given the context of incomplete cross-section model information.

hep-ph↗

arXiv2014

Using MiniBooNE NCEL and CCQE cross section results to constrain 3+1 sterile neutrino models

The MiniBooNE NCEL and CCQE cross-section measurements (neutrino running) are used to set limits in the $\Delta m^{2}-\sin^{2}\vartheta_{\mu s}$ plane for a 3+1 sterile neutrino model with a mass splitting $0.1 \leq \Delta m^{2} \leq 10.0$ eV$^{2}$. GENIE is used, with a relativistic Fermi gas model, to relate $E_{\nu}$ and the reconstructed quantities measured. The issue of uncertainty in the underlying cross-section model and its effect on the sterile neutrino limits is explored, and robust sterile neutrino limits are produced by fitting the sterile parameters and the axial-mass cross-section parameter simultaneously.

hep-ph↗