Neutrino Event Generators Research Articles

A phenomenological analysis of LHC neutrino scattering at NLO accuracy matched to parton showers

We perform a detailed phenomenological study of high-energy neutrino deep inelastic scattering (DIS) focused on LHC far-forward experiments such as FASERν\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ u $$\\end{document} and SND@LHC. To this aim, we parametrise the neutrino fluxes reaching these LHC far-forward experiments in terms of ‘neutrino PDFs’ encoding their energy and rapidity dependence by means of the LHAPDF framework. We integrate these neutrino PDFs in the recently developed POWHEG-BOX-RES implementation of neutrino-induced DIS to produce predictions accurate at next-to-leading order (NLO) in the QCD coupling matched to parton showers (PS) with Pythia8. We present NLO+PS predictions for final-state distributions within the acceptance for FASERν\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ u $$\\end{document} and SND@LHC as well as for two experiments of the proposed Forward Physics Facility (FPF), FASERν\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ u $$\\end{document}2 and FLArE. We quantify the impact of NLO QCD corrections, of the parton showering and hadronisation settings in Pythia8, of the QED shower, and of the incoming neutrino flavour for the description of these observables, and compare our predictions with the GENIE neutrino event generator. Our work demonstrates the relevance of modern higher-order event generators to achieve the key scientific targets of the LHC neutrino experiments.

Reduced cross sections of electron and neutrino charged current quasielastic scattering on nuclei

The semiexclusive averaged reduced cross sections for (anti)neutrino charged current quasielastic scattering on carbon, oxygen, and argon are analyzed within the relativistic distorted wave impulse approximation. One finds that these cross sections as functions of missing nucleon energy are similar to those of electron scattering and are in agreement with electron scattering data for the three nuclei. The difference between the electron and neutrino cross sections can be attributed to Coulomb distortion on the electron wave function. The averaged reduced cross sections depend slowly upon incoming lepton energy. The approach presented in this paper provides novel constraints on nuclear models of quasielastic neutrino-nucleus scattering and can be easily applied to test spectral functions and final state interactions employed in neutrino event generators. Published by the American Physical Society 2024

New model comparison for semi-inclusive charged-current electron and muon neutrino scattering by Ar40 in the energy range of the MicroBooNE experiment

In this work we present a comparison of semi-inclusive muon and electron neutrino cross sections with Ar40 target measured by the MicroBooNE collaboration with the predictions of an unfactorized model based on the relativistic distorted wave impulse approximation (RDWIA) and the SuSAv2-MEC model implemented in the neutrino event generator GENIE. The predictions based on the RDWIA approach, with a realistic description of the initial state and a phenomenological relativistic complex optical potential for the description of final state interactions, better describe the measured cross sections than GENIE-SuSAv2 and RDWIA with a purely real potential. Published by the American Physical Society 2024

Simulation of RPC responses in mini-Iron Calorimeter for cosmic ray muon studies

A Prototype of the Iron Calorimeter for the India-based Neutrino Observatory is currently running in Madurai, India. This consists of twenty large area single gap Resistive Plate Chambers (RPCs) of size, ∼ 185 cm × 175 cm sandwiched between 11 layers of iron plates of thickness 5.6 cm. The total size of the mini-Iron Calorimeter(mini-ICAL) is 4 m × 4 m × 1.2 m and having a weight of 85 tons is a (1/600) scaled-down version of the ICAL detector of INO [1]. The detector is magnetized using iron plates and two sets of copper coils, each coil has 18 turns. The central region of the mini-ICAL, where the RPCs are placed, has a nearly uniform magnetic field of 1.4 T, similar to the magnetic field in the final ICAL detector. This prototype serves as the basis for the design of the demonstrators, which closely mimics the characteristics of a future ICAL. This detector is built to test the final electronics in the fringe field of the magnet and also to develop the experience to construct the ICAL detector. The mini-ICAL has been operational since 2018 and collects cosmic muon data with different configurations of RPC, and electronics, which are continuously changing for various R&D efforts. Dedicated efforts are made in parallel to measure the momentum and azimuthal angle of μ+ and μ- independently, which could be an important input to the cosmic neutrino event generators. To improve the precision of those measurements a dedicated simulation effort was made, particularly in the digitisation of the RPC signal for a real detector simulation, where efficiency, noise rate, strip multiplicity, etc. were matched with the real data collected during runs at mini-ICAL.

Neutrino structure functions from GeV to EeV energies

The interpretation of present and future neutrino experiments requires accurate theoretical predictions for neutrino-nucleus scattering rates. Neutrino structure functions can be reliably evaluated in the deep-inelastic scattering regime within the perturbative QCD (pQCD) framework. At low momentum transfers (Q2 ≲ few GeV2), inelastic structure functions are however affected by large uncertainties which distort event rate predictions for neutrino energies Eν up to the TeV scale. Here we present a determination of neutrino inelastic structure functions valid for the complete range of energies relevant for phenomenology, from the GeV region entering oscillation analyses to the multi-EeV region accessible at neutrino telescopes. Our NNSFν approach combines a machine-learning parametrisation of experimental data with pQCD calculations based on state-of-the-art analyses of proton and nuclear parton distributions (PDFs). We compare our determination to other calculations, in particular to the popular Bodek-Yang model. We provide updated predictions for inclusive cross sections for a range of energies and target nuclei, including those relevant for LHC far-forward neutrino experiments such as FASERν, SND@LHC, and the Forward Physics Facility. The NNSFν determination is made available as fast interpolation LHAPDF grids, and it can be accessed both through an independent driver code and directly interfaced to neutrino event generators such as GENIE.

Simultaneous Measurement of ν_{μ} Quasielasticlike Cross Sections on CH, C, H_{2}O, Fe, and Pb as a Function of Muon Kinematics at MINERvA.

This Letter presents the first simultaneous measurement of the quasielasticlike neutrino-nucleus cross sections on C, water, Fe, Pb, and scintillator (hydrocarbon or CH) as a function of longitudinal and transverse muon momentum. The ratio of cross sections per nucleon between Pb and CH is always above unity and has a characteristic shape as a function of transverse muon momentum that evolves slowly as a function of longitudinal muon momentum. The ratio is constant versus longitudinal momentum within uncertainties above a longitudinal momentum of 4.5 GeV/c. The cross section ratios to CH for C, water, and Fe remain roughly constant with increasing longitudinal momentum, and the ratios between water or C to CH do not have any significant deviation from unity. Both the overall cross section level and the shape for Pb and Fe as a function of transverse muon momentum are not reproduced by current neutrino event generators. These measurements provide a direct test of nuclear effects in quasielasticlike interactions, which are major contributors to long-baseline neutrino oscillation data samples.

Measurement of the double-differential muon-neutrino charged-current inclusive cross section in the NOvA near detector

We report cross-section measurements of the final-state muon kinematics for νμ charged-current interactions in the NOvA near detector using an accumulated 8.09×1020 protons on target in the NuMI beam. We present the results as a double-differential cross section in the observed outgoing muon energy and angle, as well as single-differential cross sections in the derived neutrino energy, Eν, and square of the four-momentum transfer, Q2. We compare the results to inclusive cross-section predictions from various neutrino event generators via χ2 calculations using a covariance matrix that accounts for bin-to-bin correlations of systematic uncertainties. These comparisons show a clear discrepancy between the data and each of the tested predictions at forward muon angle and low Q2, indicating a missing suppression of the cross section in current neutrino-nucleus scattering models.3 MoreReceived 24 September 2021Accepted 14 February 2023DOI:https://doi.org/10.1103/PhysRevD.107.052011Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasNeutrino interactionsNucleus-neutrino interactionsParticles & Fields

Measurement of the ν_{e}-Nucleus Charged-Current Double-Differential Cross Section at ⟨E_{ν}⟩=2.4 GeV Using NOvA.

The inclusive electron neutrino charged-current cross section is measured in the NOvA near detector using 8.02×10^{20} protons-on-target in the NuMI beam. The sample of GeV electron neutrino interactions is the largest analyzed to date and is limited by ≃17% systematic rather than the ≃7.4% statistical uncertainties. The double-differential cross section in final-state electron energy and angle is presented for the first time, together with the single-differential dependence on Q^{2} (squared four-momentum transfer) and energy, in the range 1 GeV≤E_{ν}<6 GeV. Detailed comparisons are made to the predictions of the GENIE, GiBUU, NEUT, and NuWro neutrino event generators. The data do not strongly favor a model over the others consistently across all three cross sections measured, though some models have especially good or poor agreement in the single differential cross section vs Q^{2}.

Measurement of neutral current single π0 production on argon with the MicroBooNE detector

We report the first measurement of π0 production in neutral current (NC) interactions on argon with average neutrino energy of ≲1 GeV. We use data from the MicroBooNE detector’s 85 metric tons active volume liquid argon time projection chamber situated in Fermilab’s Booster Neutrino Beam and exposed to 5.89×1020 protons on target for this measurement. Measurements of NC π0 events are reported for two exclusive event topologies without charged pions. Those include a topology with two photons from the decay of the π0 and one proton and a topology with two photons and zero protons. Flux-averaged cross sections for each exclusive topology and for their semi-inclusive combination are extracted (efficiency correcting for two-plus proton final states), and the results are compared to predictions from the genie, neut, and nuwro neutrino event generators. We measure cross sections of 1.243±0.185(syst)±0.076(stat), 0.444±0.098±0.047, and 0.624±0.131±0.075 [10−38 cm2/Ar] for the semi-inclusive NCπ0, exclusive NCπ0+1p, and exclusive NCπ0+0p processes, respectively.7 MoreReceived 19 May 2022Accepted 12 December 2022DOI:https://doi.org/10.1103/PhysRevD.107.012004Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasNeutrino interactionsNucleus-neutrino interactionsParticles & Fields

Influence of Cross-Sectional Uncertainty on Sensitivity Studies of DUNE and T2HK Experiments

The ultimate objectives of ongoing and upcoming neutrino experiments are the precise measurement of neutrino mixing parameters and the confirmation of mass hierarchy. The systematic inaccuracy in the cross-section models introduces inaccuracy in the neutrino mixing parameters estimation. It is important to secure a large decrease of uncertainties, particularly those relating to cross-section, neutrino-nucleus interactions, and neutrino-energy reconstruction, in order to achieve these ambitious goals. In this research article, we use three alternative neutrino event generators, GENIE, NuWro, and GiBUU, to analyze sensitivity studies of T2HK, DUNE, and combined sensitivity of DUNE, and T2HK for mass hierarchy, CP violation, and octant degeneracy caused by cross-section uncertainties. The cross-section models of these generators are separate and independent.

Pion Production in νμ Charged Current Interactions on 40Ar in Deep Underground Neutrino Experiment

Understanding the pion generation and the consequences of final-state interactions (FSI) are critical for the data processing in all neutrino experiments. The energy utilized in modern neutrino researches of the resonance (RES) generation processes contributes significantly to the pion production. If a pion is absorbed in the nuclear matter after its production, the event may become unrecognizable from a quasielastic (QE) scattering process and act as a background. For oscillation experiments, estimating this background is critical, and it necessitates solid theoretical models for both pion generation at the primary vertex and after FSI. The number of pions created after FSI differs greatly from the number produced at the primary vertex due to FSI. Because neutrino detectors can only detect final-state particles, FSI obscures the proper information about particles created at the primary vertex. A detailed study of FSI is required to overcome this problem, which theoretical models incorporated in Monte Carlo (MC) neutrino event generators can provide. They should give theoretical results concerning the neutrino interactions for various researches, acting as a connection among both theoretical models and experimental data. In this paper, we provide simulated events for the pion creation in νμ charge current (CC) interactions on a 40Ar target in the Deep Underground Neutrino Experiment (DUNE) setup for two distinct MC generators: GENIE and NuWro. In comparison to GENIE (v-3.00.06), NuWro (v-19.02.2) is more opaque (less responsive) to the charge exchange and absorption processes; pions are more likely to be absorbed than produced during the intranuclear transport.

Uncertainties in QE and RES Events at LBNF Due to Hadronic Production in FSI

To achieve appropriate interaction rates in recent neutrino oscillation studies, high atomic number nuclear targets were utilized. Because of the nuclear effects in the experimental observable, the utilization of these complicated targets produced systematic uncertainties that needed to be assessed accurately to constrain the discovery. We made an effort to calculate the nuclear effects in the Ar and H targets, which are intended to be employed at the DUNE far and near detectors, respectively, through our simulation effort. The DUNE flux is peaking around 2.5 GeV, and CCRES is the dominant process at this energy. So, this work will be focused only on the CCQE and CCRES interactions and the simulations will be done using two different neutrino event generators. We reported the ratio of the oscillation probability (P(Ar)/P(H) as a function of reconstructed neutrino energy for CCRES channels to quantify the systematic errors in the observables.

Benchmarking intranuclear cascade models for neutrino scattering with relativistic optical potentials

The description of final-state interactions (FSI) in the large phase space probed in neutrino experiments poses a great challenge. In neutrino experiments, which operate under semi-inclusive conditions, cascade models are commonly used for this task, while under exclusive conditions FSI can be treated with relativistic optical potentials (ROP). We formulate conditions under which the ROP approach and cascade model can be directly compared. We feed the NEUT cascade with events from a relativistic distorted-wave impulse approximation calculation that uses the real part of an optical potential. Cuts on the missing energy of the resulting events are applied to define a set of events that can be directly compared to RDWIA calculations with the full optical potential. The NEUT cascade and ROP agree for proton kinetic energies $T_p > 150$ MeV for carbon, oxygen and calcium nuclei when a realistic nuclear density is used to introduce events in the cascade. For $T_p < 100$ MeV the ROP and NEUT cross sections differ in shape and differences in magnitude are larger than 50 \%. Single transverse variables allow to distinguish different approaches to FSI, but due to a large non-QE contribution the comparison to T2K data does not give an unambiguous view of FSI. We discuss electron scattering and argue that with a cut in missing energy FSI can be studied with minimal confounding factors in e.g. $e4\nu$. The agreement of the ROP and NEUT for T2K conditions lends confidence to these models as a tool in oscillation analyses for sufficiently large nucleon kinetic energies. These results urge for caution when a cascade model is applied for small nucleon energies. The assessment of model assumptions relevant to this region are strongly encouraged. This paper provides novel constraints on cascade models from proton-nucleus scattering that can be easily applied to other neutrino event generators.

Uncertainties Due to Hadronic Production in Final-State Interactions at Long-Baseline Neutrino Facility

Recent neutrino oscillation experiments used high atomic number nuclear targets to attain sufficient interaction rates. The use of these complex targets introduced systematic uncertainties due to the nuclear effects in the experimental observables and need to be measured properly to pin down the discovery. Through this simulation work, we are trying to quantify the nuclear effects in the argon (Ar) target in comparison to hydrogen (H) target which are proposed to be used at Deep Underground Neutrino Experiment far detector and near detector, respectively. Generated Events for Neutrino Interaction Experiments and NuWro, two neutrino event generators, are used to construct final state kinematics. To quantify the systematic uncertainties in the observables, we present the ratio of the oscillation probabilities (P(Ar)/P(H)) as a function of the reconstructed neutrino energy.

Analysis of the kinematic boundaries of the quasielastic neutrino-nucleus cross section in the superscaling model with a relativistic effective mass

In this work we obtain the analytical expressions for the boundaries of the charged current quasielastic (CCQE) double differential cross section in terms of dimensionless energy and momentum transfers, for the Relativistic Fermi Gas (RFG) and the Superscaling approach with relativistic effective mass (SuSAM*) models, within the scaling formalism. In addition, we show that this double differential cross section in the scaling formalism has very good properties to be implemented in the Monte Carlo (MC) neutrino event generators, particularly because its peak is almost flat with the (anti)neutrino energy. This makes it especially well suited for the event generation by the acceptance-rejection method usually used in the neutrino generators. Finally, we analyze the total CCQE cross section $\ensuremath{\sigma}({E}_{\ensuremath{\nu}})$ for both models and attribute the enhancement observed in the SuSAM* total cross section to the high-momentum components which are present, in a phenomenological way, in its scaling function, while these are absent in the RFG model.

Running axial mass of the nucleon as a phenomenological tool for calculating quasielastic neutrino\u2013nucleus cross sections

We suggest an empirical rule-of-thumb for calculating the cross sections of charged-current quasielastic (CCQE) and CCQE-like interactions of neutrinos and antineutrinos with nuclei. The approach is based on the standard relativistic Fermi-gas model and on the notion of neutrino energy dependent axial-vector mass of the nucleon, governed by a couple of adjustable parameters, one of which is the conventional charged-current axial-vector mass. The inelastic background contributions and final-state interactions are therewith simulated using GENIE 3 neutrino event generator. An extensive comparison of our calculations with earlier and current accelerator CCQE and CCQE-like data for different nuclear targets shows good or at least qualitative overall agreement over a wide energy range. We also discuss some problematical issues common to several competing contemporary models of the CCQE (anti)neutrino–nucleus scattering and to the current neutrino interaction generators.

Nuclear de-excitation associated with neutrino-carbon interactions

Neutrino interactions in low energy regions below 30 MeV, where the experimental searches for supernova relic neutrino are conducted, have a large uncertainty due to complicated nuclear effects such as the Pauli blocking effect and de-excitation of a residual nucleus. Understanding the effect of nuclear de-excitation is especially critical since neutrons measured by liquid scintillator detectors can be emitted via de-excitation. We build a systematic method to predict nuclear de-excitation associated with neutrino-carbon interaction using TALYS and Geant4. This prediction is combined with the results of neutrino event generators, and we find a large increase in neutron multiplicity.

Inclusive electron scattering and the genie neutrino event generator

The extraction of neutrino mixing parameters from accelerator-based neutrino oscillation experiments relies on proper modeling of neutrino-nucleus scattering processes using neutrino-interaction event generators. Experimental tests of these generators are difficult due to the broad range of neutrino energies produced in accelerator-based beams and the low statistics of current experiments. Here we overcome these difficulties by exploiting the similarity of neutrino and electron interactions with nuclei to test neutrino event generators using high-precision inclusive electron scattering data. To this end, we revised the electron-scattering mode of the GENIE event generator ($e$-GENIE) to include electron-nucleus bremsstrahlung radiation effects and to use, when relevant, the exact same physics models and model parameters, as the standard neutrino-scattering version. We also implemented new models for quasielastic (QE) scattering and meson exchange currents (MEC) based on the theory-inspired SuSAv2 approach. Comparing the new $e$-GENIE predictions with inclusive electron scattering data, we find an overall adequate description of the data in the QE- and MEC-dominated lower energy transfer regime, especially when using the SuSAv2 models. Higher energy transfer-interactions, which are dominated by resonance production, are still not well modeled by $e$-GENIE.

LeptonInjector and LeptonWeighter: A neutrino event generator and weighter for neutrino observatories

We present a high-energy neutrino event generator, called LeptonInjector, alongside an event weighter, called LeptonWeighter. Both are designed for large-volume Cherenkov neutrino telescopes such as IceCube. The neutrino event generator allows for quick and flexible simulation of neutrino events within and around the detector volume, and implements the leading Standard Model neutrino interaction processes relevant for neutrino observatories: neutrino-nucleon deep-inelastic scattering and neutrino-electron annihilation. In this paper, we discuss the event generation algorithm, the weighting algorithm, and the main functions of the publicly available code, with examples. Program summaryProgram Titles:LeptonInjector and LeptonWeighterCPC Library link to program files:https://doi.org/10.17632/662gkpjfd9.1Developer's repository links:https://github.com/icecube/LeptonInjector and https://github.com/icecube/LeptonWeighterLicensing provisions: GNU Lesser General Public License, version 3.Programming Language: C++11External Routines:•Boost•HDF5•nuflux (https://github.com/icecube/nuflux)•nuSQuIDS (https://github.com/arguelles/nuSQuIDS)•Photospline (https://github.com/icecube/photospline)•SuiteSparse (https://github.com/DrTimothyAldenDavis/SuiteSparse)Nature of problem:LeptonInjector: Generate neutrino interaction events of all possible topologies and energies throughout and around a detector volume.LeptonWeighter: Reweight Monte Carlo events, generated by a set of LeptonInjector Generators, to any desired physical neutrino flux or cross section.Solution method:LeptonInjector: Projected ranges of generated leptons and the extent of the detector, in terms of column depth, are used to inject events in and around the detector volume. Event kinematics follow distributions provided in cross section files.LeptonWeighter: Event generation probabilities are calculated for each Generator, which are then combined into a generation weight and used to calculate an overall event weight.

Monte Carlo event generation of neutrino–electron scattering

We describe an extension of the NuWro Monte Carlo neutrino event generator with the neutrino–electron scattering processes. This new dynamical channel includes the charged current and neutral current interactions, together with their interference, for ν ℓ e and (ℓ = e, μ, τ) scatterings, resulting in ten possible final states. We illustrate the performance of the new functionality on few physical examples, including an estimation of the background in the T2K ν μ → ν e oscillation experiment. We show that the background events arising from the neutrino–electron interactions occupy mostly a distinct region of the phase space and can be easily separated.