Incident Neutrino Energy Research Articles

Tau polarization in neutrino-nucleus interactions at the LHC energy range

Considering that the study of neutrino-nucleus interactions with incident neutrino energy ranges in the GeV–TeV range is feasible at the Large Hadron Collider, we investigate in this paper the degree of polarization P of the (anti)tau lepton produced in (anti)tau neutrino-tungsten interactions. We estimate the differential cross sections and the longitudinal and transverse components of the tau lepton polarization as a function of the tau lepton energy and distinct values of the scattering angle, assuming different values for the energy of the incoming (anti)tau neutrino. Different models for the treatment of the nuclear effects in the parton distribution functions are assumed as input in the calculations. Our results indicate that P<1 for the neutrino energies reached at the LHC and are almost insensitive to the nuclear effects. Published by the American Physical Society 2024

Inclusive quasielastic neutrino-nucleus scattering with energy density functional nuclear models* *Supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (2018R1A5A1025563, 2023R1A2C1003177, IBS-R031-D1)

In this study, we calculated the inclusive charged-current neutrino-nucleus scattering from 40Ar in the quasielastic region. To explore the effect of uncertainties stemming from the nuclear structure, we used the KIDS (Korea-IBS-Daegu-SKKU) nuclear energy density functional and Skyrme force models, namely SLy4, SkI3, and MSk7. These models were selected to have distinct behavior in terms of the density dependence of the symmetry energy and the effective mass of the nucleon. In the charged-current neutrino scattering, the single- and double-differential cross sections were calculated for various kinematics. Total cross sections are reported as a function of the incident neutrino energy. The theoretical cross sections were compared with experimental data, and the roles of the effective mass and symmetry energy were investigated in terms of charged-current neutrino-nucleus scattering.

First Direct Observation of Collider Neutrinos with FASER at the LHC.

We report the first direct observation of neutrino interactions at a particle collider experiment. Neutrino candidate events are identified in a 13.6TeV center-of-mass energy pp collision dataset of 35.4 fb^{-1} using the active electronic components of the FASER detector at the Large Hadron Collider. The candidates are required to have a track propagating through the entire length of the FASER detector and be consistent with a muon neutrino charged-current interaction. We infer 153_{-13}^{+12} neutrino interactions with a significance of 16 standard deviations above the background-only hypothesis. These events are consistent with the characteristics expected from neutrino interactions in terms of secondary particle production and spatial distribution, and they imply the observation of both neutrinos and anti-neutrinos with an incident neutrino energy of significantly above 200GeV.

Quasielastic charged-current neutrino-nucleus scattering with relativistic nuclear models

Charged-current neutrino-nucleus scattering is studied in the quasielastic region with various relativistic nuclear models that include the relativistic Hartree, the nonlinear $\ensuremath{\sigma}$, the quark-meson coupling, and the chiral quark-meson coupling models. Theoretical results at several kinematics are compared with experimental data measured from MiniBooNE, T2K, MicroBooNE, and SciBooNE. While the theoretical double-differential cross sections in terms of the kinetic energy and polar angle of outgoing muon describe the T2K data well, the single-differential cross sections in terms of energy loss and the total cross sections of incident neutrino energy do not properly describe MiniBooNE, MicroBooNE, and SciBooNE data. Additionally, differences from the relativistic nuclear models are examined in detail by comparing with the experimental data. In particular, the MiniBooNE data are not consistent with MicroBooNE and SciBooNE data, where the incident neutrino energies are below 1 GeV.

Weak process for Iron isotopes chain used as seed for heavy elements nucleosynthesis

The weak processes are a key to understand the nucleosynthesis of heavy elements in the universe. In this work we have studied weak processes such as β-decay and neutrino capture that are very important for the r-process. This process takes place in a region between neutron drip and β-stability line. For nuclei far from β-stability line the experimental data are very scarce. To study the nucleosynthesis of heavy elements in astrophysics sites like Binary Neutron Star merger (BNS) and Supernova explosions, we have employed the Gross Theory of Beta Decay (GTBD) to evaluate the neutrino-nucleus cross sections and β-decay half-lives. Our 56Fe(νe , e −)56Co cross section show a excelent agreement with microscopic models and the half-lives well reproduce the experimental data with a satisfactory accuracy. We have fitted the neutrino-nucleus cross sections obtained by GTBD using a four degree polynomial dependence of the incident neutrino energy. This dependence allows us to systematically calculate the neutrino-nucleus cross sections for a large amount of nuclei, as occurs in the r-process nucleosynthesis calculation (more than 4000 nuclei). Our fitting and interpolation procedures are shown to be in a good agreement and the GTBD cross sections are successfully reproduced.

Neutral-current neutrino scattering from the deuteron

Neutral-current neutrino scattering from the deuteron leading to proton-neutron final states is considered using an approach that incorporates relativistic dynamics and consequently provides robust modeling at relatively high energies and momenta. In this work the focus is placed on the fully exclusive reaction where both the proton and neutron in the final state are assumed to be detected. Accordingly, the incident neutrino energy, the neutrino scattering angle and the scattered neutrino's energy can all be reconstructed. It is shown that for specific choices of kinematics the reaction proceeds mainly via scattering from the proton, while for other choices of kinematics it proceeds mainly from the neutron. Specific asymmetries are introduced to focus on these attributes. Measurements in both regions have the potential to yield valuable information on the nucleon's electroweak form factors at momentum transfers up to a (GeV/c)$^2$. In particular, the cross sections are shown to be very sensitive to the isoscalar axial-vector form factor, and sensitive but less so to the magnetic strangeness form factor. Comparisons with other reactions, specifically charge-changing neutrino reactions and both parity-conserving and -violating electron scattering, have the potential to provide new ways to test the Standard Model.

Neutrino-deuteron scattering: Uncertainty quantification and new L1,A constraints

We study neutral- and charged-current (anti)neutrino-induced dissociation of the deuteron at energies from threshold up to 150 MeV by employing potentials, as well as one- and two-body currents, derived in chiral effective field theory ($\chi$EFT). We provide uncertainty estimates from $\chi$EFT truncations of the electroweak current, dependences on the $\chi$EFT cutoff and variations in the pool of fit data used to fix the low-energy constants of $\chi$EFT. At 100 MeV of incident (anti)neutrino energy, these uncertainties amount to about 2-3\% and are smaller than the sensitivity of the cross sections to the single-nucleon axial form factor, which amounts to 5\% if one varies the range of the nucleon axial radius within the bands determined by recent lattice quantum chromodynamics evaluations and phenomenological extractions. We conclude that a precise determination of the nucleon axial form factor is required for a high-precision calculation of the neutrino-deuteron cross sections at energies higher than 100 MeV. By matching our low-energy $\chi$EFT results to those of pionless effective field theory ($\cancel{\pi}$EFT), we provide new constraints for the counterterm $L_{1,A}$ that parameterizes the strength of the axial two-body current in $\cancel{\pi}$EFT. We obtain a value of $4.9^{+1.9}_{-1.5}\mathrm{fm}^3$ at renormalization scale set to pion mass, which is compatible with, albeit narrower than, previous experimental determinations, and comparable to a recent lattice quantum chromodynamics calculation.

Role of axial mass and strange axial form factor from various target nuclei in neutrino-nucleus scattering

The roles of strange axial form factor and axial mass for both neutral-current and charged-current reactions are investigated in the quasi-elastic neutrino-nucleus scattering within a relativistic single-particle model. The calculation is performed for various target nuclei like $^{12}\mathrm{C}$, $^{40}\mathrm{Ca}$, $^{56}\mathrm{Fe}$, and $^{208}\mathrm{Pb}$ at the incident neutrino (antineutrino) energies of 1.0 and 2.0 GeV. Then we discuss the dependence of differential cross section on the role of axial mass and strange axial form factor with different target nuclei on both neutral-current and charged-current reactions. Finally we compare our results with the MiniBooNE, T2K, and $\mathrm{MINER}\ensuremath{\nu}\mathrm{A}$ experimental data for the double-differential cross section and the scaled total cross section.

Measurements of the inclusive neutrino and antineutrino charged current cross sections in MINERvA using the low- ν flux method

The total cross sections are important ingredients for the current and future neutrino oscillation experiments. We present measurements of the total charged-current neutrino and antineutrino cross sections on scintillator (CH) in the NuMI low-energy beamline using an {\em in situ} prediction of the shape of the flux as a function of neutrino energy from 2--50 GeV. This flux prediction takes advantage of the fact that neutrino and antineutrino interactions with low nuclear recoil energy ($\nu$) have a nearly constant cross section as a function of incident neutrino energy. This measurement is the lowest energy application of the low-$\nu$ flux technique, the first time it has been used in the NuMI antineutrino beam configuration, and demonstrates that the technique is applicable to future neutrino beams operating at multi-GeV energies. The cross section measurements presented are the most precise measurements to date below 5 GeV.

“Hammer” events, neutrino energies, and nucleon-nucleon correlations

Neutrino oscillation measurements depend on a difference between the rate of neutrino-nucleus interactions at different neutrino energies or different distances from the source. Knowledge of the neutrino energy spectrum and neutrino-detector interactions are crucial for these experiments. Short range nucleon-nucleon correlations in nuclei (SRC) affect properties of nuclei. The ArgoNeut liquid Argon Time Projection Chamber (lArTPC) observed neutrino-argon scattering events with two protons back-to-back in the final state ("hammer" events) which they associated with SRC pairs. The MicroBoone lArTPC will measure far more of these events. We simulate hammer events using two simple models. We use the well-known electron-nucleon cross section to calculate e-argon interactions where the e- scatters from a proton, ejecting a pi+, and the pi+ is then absorbed on a moving deuteron-like $np$ pair. We also use a model where the electron excites a nucleon to a Delta, which then deexcites by interacting with a second nucleon. The pion production model results in two protons very similar to those of the hammer events. These distributions are insensitive to the momentum of the $np$ pair that absorbed the $\pi$. The incident neutrino energy can be reconstructed from just the outgoing lepton. The Delta process results in two protons that are less similar to the observed events. ArgoNeut hammer events can be described by a simple pion production and reabsorption model. These hammer events in MicroBooNE can be used to determine the incident neutrino energy but not to learn about SRC. We suggest that this reaction channel could be used for neutrino oscillation experiments to complement other channels with higher statistics but different systematic uncertainties.

Measurement of Electron Neutrino Quasielastic and Quasielasticlike Scattering on Hydrocarbon at ⟨E_{ν}⟩=3.6 GeV.

The first direct measurement of electron neutrino quasielastic and quasielasticlike scattering on hydrocarbon in the few-GeV region of incident neutrino energy has been carried out using the MINERvA detector in the NuMI beam at Fermilab. The flux-integrated differential cross sections in the electron production angle, electron energy, and Q^{2} are presented. The ratio of the quasielastic, flux-integrated differential cross section in Q^{2} for ν_{e} with that of similarly selected ν_{μ}-induced events from the same exposure is used to probe assumptions that underpin conventional treatments of charged-current ν_{e} interactions used by long-baseline neutrino oscillation experiments. The data are found to be consistent with lepton universality and are well described by the predictions of the neutrino event generator GENIE.

Ambiguity of the final state interaction for neutral-current neutrino-nucleus scattering in the quasielastic region

We investigate the effect of final state interaction (FSI) on the neutrino (antineutrino) scattering via neutral current from a ${}^{12}$C target in the quasielastic region within the framework of a relativistic single-particle model. Three different descriptions of the FSI, which are a relativistic mean field, a complex optical potential, and its real potential, are taken into account for two incident neutrino energies of 500 MeV and 1 GeV. The effects of the FSI are studied not only on the differential cross sections but also on each longitudinal, transverse, and transverse interference cross section. We found that the FSI description may play a vital role for the estimation of those cross sections, and the FSI effects on each response cross section may differ from those on the differential cross section. However, the asymmetry between neutrino and antineutrino scattering cross sections turns out to be nearly independent of the FSI descriptions. Finally, possible FSI effects on the MiniBooNE data are studied in detail.

Impact of nuclear effects on weak pion production at energies below 1 GeV

Charged-current single pion production in scattering off 12C is investigated for neutrino energies up to 1 GeV. An impact of nuclear effects with in-medium modifications of the Delta(1232) resonance properties as well as an effective field theory nonresonant background contribution are discussed. Dependence of the fraction of Delta(1232) decays into npnh states on incident neutrino energy is estimated. A model of Nieves et al. [1] is further developed by performing exact integration avoiding several approximations. The effect of exact integration is investigated both for double-differential and total neutrino-nucleus cross sections.

Inclusive charged-current neutrino-nucleus scattering in the quasielastic region

We study inclusive charged-current reaction through total cross sections of neutrino-nucleus scattering within the framework of a relativistic single-particle model in the quasielastic region. To describe the final-state interaction between knocked-out nucleons and the residual nucleus, a real potential of final nucleons, which is generated by a relativistic mean field, is used with the assumption of no loss of flux, which leads to current conservation and gauge invariance. We calculate $({\ensuremath{\nu}}_{\ensuremath{\mu}},{\ensuremath{\mu}}^{\ensuremath{-}})$ and $({\mathrm{\ensuremath{\nu}\ifmmode \bar{}\else \={}\fi{}}}_{\ensuremath{\mu}},{\ensuremath{\mu}}^{+})$ reactions. In these calculations, $^{12}\mathrm{C}$, $^{40}\mathrm{Ca}$, and $^{208}\mathrm{Pb}$ are used as target nuclei and the incident neutrino (antineutrino) energies are exploited up to 4 GeV. We find that the effect of the final-state interaction by the real potential of the knocked-out nucleons reduces cross sections by about 15%, similar to the effect of electron scattering. Furthermore, the effect of the Coulomb distortion for the outgoing leptons is shown to be different from the electron scattering. Finally, our total cross sections by scaling number of participated nucleons are presented to compare with experimental data.

QRAP: A numerical code for projected (Q)uasiparticle (RA)ndom (P)hase approximation

A computer code for quasiparticle random phase approximation – QRPA and projected quasiparticle random phase approximation – PQRPA models of nuclear structure is explained in details. The residual interaction is approximated by a simple δ-force. An important application of the code consists in evaluating nuclear matrix elements involved in neutrino–nucleus reactions. As an example, cross sections for 56Fe and 12C are calculated and the code output is explained. The application to other nuclei and the description of other nuclear and weak decay processes are also discussed. Program summary Title of program: QRAP ( Quasiparticle RAndom Phase approximation) Computers: The code has been created on a PC, but also runs on UNIX or LINUX machines Operating systems: WINDOWS or UNIX Program language used: Fortran-77 Memory required to execute with typical data: 16 Mbytes of RAM memory and 2 MB of hard disk space No. of lines in distributed program, including test data, etc.: ∼ 8000 No. of bytes in distributed program, including test data, etc.: ∼ 256 kB Distribution format: tar.gz Nature of physical problem: The program calculates neutrino– and antineutrino–nucleus cross sections as a function of the incident neutrino energy, and muon capture rates, using the QRPA or PQRPA as nuclear structure models. Method of solution: The QRPA, or PQRPA, equations are solved in a self-consistent way for even–even nuclei. The nuclear matrix elements for the neutrino–nucleus interaction are treated as the beta inverse reaction of odd–odd nuclei as function of the transfer momentum. Typical running time: ≈ 5 min on a 3 GHz processor for Data set 1.

The directional dependence of apertures, limits and sensitivity of the lunar Cherenkov technique to a UHE neutrino flux

We use computer simulations to obtain the directional-dependence of the lunar Cherenkov technique for ultra-high energy (UHE) neutrino detection. We calculate the instantaneous effective area of past lunar Cherenkov experiments at Parkes, Goldstone (Goldstone Lunar Ultra-high energy neutrino Experiment, GLUE), and Kalyazin, as a function of neutrino arrival direction, finding that the potential sensitivity to a point source of UHE neutrinos for these experiments was as much as thirty times that to an isotropic flux, depending on the beam-pointing position and incident neutrino energy. Convolving our results with the known lunar positions during the Parkes and Goldstone experiments allows us to calculate an exposure map, and hence the directional-dependence of the combined limit imposed by these experiments. In the 10 21–10 23 eV range, we find parts of the sky where the GLUE limit likely still dominates, and areas where none of the limits from either Parkes, GLUE, or experiments such as the Antarctic Impulsive Transient Antenna (ANITA) balloon experiment or FORTE (Fast On-orbit Recording of Transient Events) satellite experiment are likely to be significant. Hence a large anisotropic flux of UHE neutrinos from these regions is not yet excluded. We also determine the directional dependence of the aperture of future planned experiments with the Australia Telescope Compact Array (ATCA), Australian SKA Pathfinder (ASKAP) and the Square Kilometre Array (SKA) to a UHE neutrino flux, and calculate the potential annual exposure to astronomical objects as a function of angular distance from the lunar trajectory through celestial coordinates. We find that the potential exposure of all experiments at 10 20 eV and below, integrated over a calendar year, is flat out to ∼25° from the lunar trajectory and then drops off rapidly. The region of greater sensitivity includes much of the Supergalactic Plane, including M87 and Cen A, as well as the Galactic Centre. At higher energies this high-sensitivity region becomes broader, and we find that the potential exposure of the SKA at 10 21 eV and above is almost uniform over celestial coordinates.

Detection of supernova neutrinos with neutrino-iron scattering

The ${\ensuremath{\nu}}_{e}$-$^{56}\mathrm{Fe}$ cross section is evaluated in the projected quasiparticle random phase approximation (PQRPA). This model solves the puzzle observed in RPA for nuclei with mass around $^{12}\mathrm{C}$, because it is the only RPA model that treats the Pauli Principle correctly. The cross sections as a function of the incident neutrino energy are compared with recent theoretical calculations of similar models. The average cross section weighted with the flux spectrum yields a good agreement with the experimental data. The expected number of events in the detection of supernova neutrinos is calculated for the LVD detector, leading to an upper limit for the electron neutrino energy of particular importance in this experiment.

Strange-quark contribution to the ratio of neutral- to charged-current cross sections in neutrino-nucleus scattering

A formalism based on a relativistic plane-wave impulse approximation is developed to investigate the strange-quark content g{sub A}{sup s} of the axial-vector form factor of the nucleon via neutrino-nucleus scattering. Nuclear structure effects are incorporated via an accurately calibrated relativistic mean-field model. The ratio of neutral- to charged-current cross sections is used to examine the sensitivity of this observable to g{sub A}{sup s}. For values of the incident neutrino energy in the range proposed by the FINeSSE Collaboration and by adopting a value of g{sub A}{sup s}=-0.19, a 30% enhancement in the ratio is observed relative to the g{sub A}{sup s}=0 result.

Electron- and neutrino-nucleus scattering in the impulse approximation regime

A quantitative understanding of the weak nuclear response is a prerequisite for the analyses of neutrino experiments such as K2K and MiniBOONE, which measure energy and angle of the muons produced in neutrino-nucleus interactions in the energy range $0.5-3$ GeV and reconstruct the incident neutrino energy to determine neutrino oscillations. In this paper we discuss theoretical calculations of electron- and neutrino-nucleus scattering, carried out within the impulse approximation scheme using realistic nuclear spectral functions.Comparison between electron scattering data and the calculated inclusive cross section off oxygen, at beam energies ranging between 700 and 1200 MeV, show that the Fermi gas model, widely used in the analysis of neutrino oscillation experiments,fails to provide a satisfactory description of the measured cross sections,and inclusion of nuclear dynamics is needed.

High Energy Neutrino Cross Sections

The theoretical status of the neutrino-nucleon cross section is reviewed for incident neutrino energies up to E ν = 10 12 GeV , including different approaches to high energy extrapolations. Nonstandard model or nonperturbative physics may play a role at ultrahigh energies. The cases of mini-black hole production and electroweak instanton contributions are discussed as examples in the context of ultrahigh energy neutrino scattering.