Charged Current Quasi-elastic Research Articles

Quantifying Effects of Final-State Interactions on Energy Reconstruction in DUNE

In neutrino-nucleus interactions, the particles produced at the primary vertex may be different from the particles observed in the final state. This is due to the effect of final-state interactions (FSI) on the particles during their transport in the nuclear matter to reach the detector (final state) after their production at the primary vertex. In this report, the energy reconstruction is done for charged current quasielastic (CCQE) and charged current resonance (CCRES) scatterings on the event-by-event basis using the calorimetric method, and NuWro and GENIE simulation tools. In addition, the percentage of fake events in CCQE and CCRES interactions is presented. It is found that the percentage of fake events is more than 50% for both CCQE and CCRES processes for both the generators, if we apply the condition for the signal events that the particles observed in the final state should be the same as the particles produced at the primary vertex. Based on our definition of signal events, the reconstructed energy and number of fake events may change, and this influences the measurement of oscillation parameters in long-baseline experiments like DUNE.

Search for an anomalous excess of charged-current quasielastic νe interactions with the MicroBooNE experiment using Deep-Learning-based reconstruction

We present a measurement of the νe-interaction rate in the MicroBooNE detector that addresses the observed MiniBooNE anomalous low-energy excess (LEE). The approach taken isolates neutrino interactions consistent with the kinematics of charged-current quasielastic (CCQE) events. The topology of such signal events has a final state with one electron, one proton, and zero mesons (1e1p). Multiple novel techniques are employed to identify a 1e1p final state, including particle identification that use two methods of Deep-Learning-based image identification and event isolation using a boosted decision-tree ensemble trained to recognize two-body scattering kinematics. This analysis selects 25 νe-candidate events in the reconstructed neutrino energy range of 200–1200 MeV, while 29.0±1.9(sys)±5.4(stat) are predicted when using νμ CCQE interactions as a constraint. We use a simplified model to translate the MiniBooNE LEE observation into a prediction for a νe signal in MicroBooNE. A Δχ2 test statistic, based on the combined Neyman–Pearson χ2 formalism, is used to define frequentist confidence intervals for the LEE signal strength. Using this technique, in the case of no LEE signal, we expect this analysis to exclude a normalization factor of 0.75 (0.98) times the median MiniBooNE LEE signal strength at 90% (2σ) confidence level, while the MicroBooNE data yield an exclusion of 0.25 (0.38) times the median MiniBooNE LEE signal strength at 90% (2σ) confidence level.40 MoreReceived 28 October 2021Accepted 25 March 2022DOI:https://doi.org/10.1103/PhysRevD.105.112003Published 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)Physical SystemsNeutrinosParticles & Fields

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.

First Measurement of Differential Charged Current Quasielasticlike ν_{μ}-Argon Scattering Cross Sections with the MicroBooNE Detector.

We report on the first measurement of flux-integrated single differential cross sections for charged-current (CC) muon neutrino (ν_{μ}) scattering on argon with a muon and a proton in the final state, ^{40}Ar (ν_{μ},μp)X. The measurement was carried out using the Booster Neutrino Beam at Fermi National Accelerator Laboratory and the MicroBooNE liquid argon time projection chamber detector with an exposure of 4.59×10^{19} protons on target. Events are selected to enhance the contribution of CC quasielastic (CCQE) interactions. The data are reported in terms of a total cross section as well as single differential cross sections in final state muon and proton kinematics. We measure the integrated per-nucleus CCQE-like cross section (i.e., for interactions leading to a muon, one proton, and no pions above detection threshold) of (4.93±0.76_{stat}±1.29_{sys})×10^{-38} cm^{2}, in good agreement with theoretical calculations. The single differential cross sections are also in overall good agreement with theoretical predictions, except at very forward muon scattering angles that correspond to low-momentum-transfer events.

Parametrization and applications of the low- Q2 nucleon vector form factors

We present the proton and neutron vector form factors in a convenient parametric form that is optimized for momentum transfers $\lesssim$ few GeV$^2$. The form factors are determined from a global fit to electron scattering data and precise charge radius measurements. A new treatment of radiative corrections is applied. This parametric representation of the form factors, uncertainties and correlations provides an efficient means to evaluate many derived observables. We consider two classes of illustrative examples: neutrino-nucleon scattering cross sections at GeV energies for neutrino oscillation experiments and nucleon structure corrections for atomic spectroscopy. The neutrino-nucleon charged current quasielastic (CCQE) cross section differs by 3-5% compared to commonly used form factor models when the vector form factors are constrained by recent high-statistics electron-proton scattering data from the A1 Collaboration. Nucleon structure parameter determinations include: the magnetic and Zemach radii of the proton and neutron, $[r_M^p, r_M^n] = [ 0.739(41)(23), 0.776(53)(28)]$ fm and $[r_Z^p, r_Z^n] = [ 1.0227(94)(51), -0.0445(14)(3)]$ fm; the Friar radius of nucleons, $[(r^p_F)^3, (r^n_F)^3] = [2.246(58)(2), 0.0093(6)(1)]$ fm$^3$; the electric curvatures, $[\langle r^4 \rangle^p_E, \langle r^4 \rangle^n_E ] = [1.08(28)(5), -0.33(24)(3)]$ fm$^4$; and bounds on the magnetic curvatures, $[ \langle r^4 \rangle^p_M, \langle r^4 \rangle^n_M ] = [ -2.0(1.7)(0.8), -2.3(2.1)(1.1)]$ fm$^4$. The first and dominant uncertainty is propagated from the experimental data and radiative corrections, and the second error is due to the fitting procedure.

Ab Initio Study of (νℓ,ℓ−) and (ν¯ℓ,ℓ+) Inclusive Scattering in C12 : Confronting the MiniBooNE and T2K CCQE Data

We carry out an ab initio calculation of the neutrino flux-folded inclusive cross sections, measured on $^{12}$C by the MiniBooNE and T2K collaborations in the charged-current quasielastic (CCQE) regime. The calculation is based on realistic two- and three-nucleon interactions, and on a realistic nuclear electroweak current with one-and two-nucleon terms that are constructed consistently with these interactions and reproduce low-energy electroweak transitions. Numerically exact quantum Monte Carlo methods are utilized to compute the nuclear weak response functions, by fully retaining many-body correlations in the initial and final states and interference effects between one- and two-body current contributions. We employ a nucleon axial form factor of the dipole form with $\Lambda_A = 1.0$ or $1.15$ GeV, the latter more in line with a very recent lattice QCD determination. The calculated cross sections are found to be in good agreement with the neutrino data of MiniBooNE and T2K, and antineutrino MiniBooNE data, yielding a consistent picture of nuclei and their electroweak properties across a wide regime of energy and momenta.

Testing of quasi-elastic neutrino charged-current and two-body meson exchange current models with the MiniBooNE neutrino data and analysis of these processes at energies available at the NOvA experiment

The charged-current quasi-elastic (CCQE) scattering of muon neutrinos on a carbon target is analyzed using the relativistic distorted-wave impulse approximation (RDWIA) taking into account the contribution of the two-particle and two-hole meson exchange current ($2p-2h$ MEC) to the weak response functions. A fit the RDWIA+MEC model to the MiniBooNE neutrino data is performed and the best fit value of nucleon axial mass $M_A=1.2 \pm 0.06$ GeV is obtained. We also extract the values of the axial form factor $F_A(Q^2)$ as a function of the squared momentum transfer $Q^2$ from the measured $d\sigma/dQ^2$ cross section. The flux-integrated CCQE-like differential cross sections for neutrino scattering at energies of the NOvA experiment are estimated within the RDWIA+MEC approach.

Testing charged current quasi-elastic and multinucleon interaction models in the NEUT neutrino interaction generator with published datasets from the MiniBooNE and MINERνA experiments

The MiniBooNE large axial mass anomaly has prompted a great deal of theoretical work on sophisticated Charged Current Quasi-Elastic (CCQE) neutrino interaction models in recent years. As the dominant interaction mode at T2K energies, and the signal process in oscillation analyses, it is important for the T2K experiment to include realistic CCQE cross section uncertainties in T2K analyses. To this end, T2K's Neutrino Interaction Working Group has implemented a number of recent models in NEUT, T2K's primary neutrino interaction event generator. In this paper, we give an overview of the models implemented, and present fits to published muon neutrino and muon antineutrino CCQE cross section measurements from the MiniBooNE and MINERvA experiments. The results of the fits are used to select a default cross section model for future T2K analyses, and to constrain the cross section uncertainties of the model. We find a model consisting of a modified relativistic Fermi gas model and multinucleon interactions most consistently describes the available data.

Status of GADZOOKS!: Neutron Tagging in Super-Kamiokande

The GADZOOKS! project pursues the upgrade of the Super-Kamiokande detector as a way to efficiently detect thermal neutrons. Inverse beta decay reactions, as well as charged current quasi-elastic (CCQE) scattering of low energy anti-neutrinos (up to a few hundreds of MeV) in SK, produce one positron and one neutron in the final state. Being able to observe the final state neutron in coincidence with the prompt positron would mean that SK could identify these reactions as genuine with very high confidence.GADZOOKS! will open to Super-Kamiokande - and water Cherenkov detectors in general - a wealth of physics currently inaccessible due to background limitations. The most important is observing for the first time the diffuse supernova neutrino background: Super-Kamiokande enriched with gadolinium will discover it after few years of running.The main R&D program towards GADZOOKS! is EGADS: a 200 ton fully instrumented tank built in a new cavern in the Kamioka mine. EGADS incorporates all the necessary subsystems to make GADZOOKS! a reality. In this contribution we will describe EGADS, we will present its current status and discuss the main results and conclusions arrived at so far. In addition, we will analyze other issues specific to the running of GADZOOKS!.

Measurement of theνμcharged-current quasielastic cross section on carbon with the ND280 detector at T2K

The Charged-Current Quasi-Elastic (CCQE) interaction, $\nu_{l} + n \rightarrow l^{-} + p$, is the dominant CC process at $E_\nu \sim 1$ GeV and contributes to the signal in accelerator-based long-baseline neutrino oscillation experiments operating at intermediate neutrino energies. This paper reports a measurement by the T2K experiment of the $\nu_{\mu}$ CCQE cross section on a carbon target with the off-axis detector based on the observed distribution of muon momentum ($p_\mu$) and angle with respect to the incident neutrino beam ($\theta_\mu$). The flux-integrated CCQE cross section was measured to be $(0.83 \pm 0.12) \times 10^{-38}\textrm{ cm}^{2}$ in good agreement with NEUT MC value of ${0.88 \times 10^{-38}} \textrm{ cm}^{2}$. The energy dependence of the CCQE cross section is also reported. The axial mass, $M_A^{QE}$, of the dipole axial form factor was extracted assuming the Smith-Moniz CCQE model with a relativistic Fermi gas nuclear model. Using the absolute (shape-only) $p_{\mu}cos\theta_\mu$ distribution, the effective $M_A^{QE}$ parameter was measured to be ${1.26^{+0.21}_{-0.18} \textrm{ GeV}/c^{2}}$ (${1.43^{+0.28}_{-0.22} \textrm{ GeV}/c^{2}}$).

Electron and Muon production cross-sections in quasielastic ν(ν̄)-Nucleus scattering for Eν < 1GeV

In this paper, we have studied (anti)neutrino induced charged current quasielastic (CCQE) scattering from some nuclear targets in the energy region of [Formula: see text]. Our aim is to confront electron and muon production cross-sections relevant for [Formula: see text] or [Formula: see text] oscillation experiments. The effects due to lepton mass and its kinematic implications, radiative corrections, second class currents (SCCs) and uncertainties in the axial and pseudoscalar form factors are calculated for (anti)neutrino induced reaction cross-sections on free nucleon as well as the nucleons bound in a nucleus where nuclear medium effects influence the cross-section. For the nuclear medium effects, we have taken some versions of Fermi gas model (FGM) available in the literature. The results for (anti)neutrino–nucleus scattering cross-section per interacting nucleons are compared with the corresponding results in free nucleon case.

Using MiniBooNE neutral current elastic cross section results to constrain 3+1 sterile neutrino models

The MiniBooNE Neutral Current Elastic (NCEL) cross section results are used to extract 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 cross section model close to the one employed by MiniBooNE to make event rate predictions using simulations on the MiniBooNE target material CH$_{2}$. The axial mass is a free parameter in all fits. Sterile modifications to the flux and changes to the cross section in the simulation relate the two and allow limits to be set on sterile neutrino mixing using cross section results. The large axial mass problem makes it necessary for experiments to perform their own axial mass fits, but a prior fit to the same dataset could mask a sterile oscillation signal if the sterile and cross section model parameters are not independent. We find that for the NCEL dataset there are significant correlations between the sterile and cross section model parameters, making a fit to both models simultaneously necessary to get robust results. Failure to do this results in stronger than warranted limits on the sterile parameters. The general problems that the current uncertainty on charged-current quasi-elastic (CCQE) and NCEL cross sections at MiniBooNE energies pose for sterile neutrino measurements are discussed.

Physics potential of neutrino oscillation experiment with a far detector in Oki Island along the T2K baseline

Oki Island is located between Japan and Korea along the Tokai-To-Kamioka (T2K) baseline. The distance from J-PARC to Oki Island is about 653km, which is twice that of the T2K experiment (L=295km). When the off-axis angle of the neutrino beam from J-PARC is 3.0^\circ (2.0^\circ) at Super-Kamiokande (SK), the off-axis beam (OAB) with 1.4^\circ (0.6^\circ) reaches at Oki Island. We examine physics case of placing a far detector in Oki Island during the T2K experimental period. We estimate the matter density profile along the Tokai-to-Oki baseline by using recent seismological measurements. For a detector of 100kton fiducial volume and 2.5x10^21 POT (protons on target) exposure for both \nu_\mu and \bar{\nu}_\mu beams, we find that the mass hierarchy pattern can be distinguished at 3\sigma level if sin^22theta_rct \equiv 4|U_{e3}|^2(1-|U_{e3}|^2) \gsim 0.09, by observing the electron-like CCQE (Charged-Current Quasi Elastic) events. The CP phase in the Maki-Nakagawa-Sakata lepton flavor mixing matrix, \delta_mns, can be constrained with \pm 20^\circ. As a reference, we repeat the same analysis by placing the same detector in Korea at L=1000km and OAB=0.5^\circ (T2KK) and also by placing it at the SK site (T2K_122). The Tokai-to-Kamioka-OKI (T2KO) sensitivity to the mass hierarchy is about 1/3 (in \Delta \chi^2_min) of T2KK, while the sensitivity to the phase \delta_mns is similar between T2KO and T2KK. The T2K_122 option has almost no sensitivity to the mass hierarchy, and cannot measure the CP phase except when \delta_mns \sim -90^\circ (90^\circ) for the normal (inverted) hierarchy.

CC and NC Pion Production

The disappearance searching experiments use charged current quasielastic (CCQE) reaction to detect an arriving neutrino and reconstruct its energy, while the CC1π+ production can mimic the CCQE signal process. In appearance experiments, the NC1π0 production process can lead to a fake e- event by the impossibility for the detector of distinguish an arriving electron or a photon. Here we present a consistent model, from the point of view of the construction of the elemental amplitude, for the mentioned pion production background processes including bounding, smearing and final state interaction (FSI) effects in a single fashion. Results are comparable with more evolved approaches based on Monte Carlo simulations.

Consistent analysis of neutral- and charged-current neutrino scattering off carbon

Background: Good understanding of the cross sections for (anti)neutrino scattering off nuclear targets in the few-GeV energy region is a prerequisite for correct interpretation of results of ongoing and planned oscillation experiments. Purpose: Clarify possible source of disagreement between recent measurements of the cross sections on carbon. Method: Nuclear effects in (anti)neutrino scattering off carbon nucleus are described using the spectral function approach. The effect of two- and multi-nucleon final states is accounted for by applying an effective value of the axial mass, fixed to 1.23 GeV. Neutral-current elastic (NCE) and charged-current quasielastic (CCQE) processes are treated on equal footing. Results: The differential and total cross sections for the energy ranging from a few hundreds of MeV to 100 GeV are obtained and compared to the available data from the BNL E734, MiniBooNE, and NOMAD experiments. Conclusions: Nuclear effects in NCE and CCQE scattering seem to be very similar. Within the spectral function approach, the axial mass from the shape analysis of the MiniBooNE data is in good agreement with the results reported by the BNL E734 and NOMAD Collaborations. However, the combined analysis of NCE and CCQE data does not seem to support the contribution of multi-nucleon final states being large enough to explain the normalization of the MiniBooNE-reported cross sections.

Measurement of the off-axis NuMI Neutrinos

An analysis of the off-axis beam is discussed. Fermi National Accelerator Laboratory has two beam lines that produce neutrinos: the Booster Neutrino Beam (BNB) and the NuMI beam line. The BNB beam is designed for use by the MiniBooNE experiment. The NuMI beam produces neutrinos for the MINOS experiment and it will be supplying the NOνA experiment with neutrinos. The MiniBooNE detector also observes neutrinos from the NuMI beamline, at an off-axis angle of 6.3 degrees. Samples of charged current quasi-elastic (CCQE) νμ and νe interactions were analyzed.

Relativistic models for quasielastic electron and neutrino-nucleus scattering

Relativistic models developed within the framework of the impulse approximation for quasielastic (QE) electron scattering and successfully tested in comparison with electron-scattering data have been extended to neutrino-nucleus scattering. Different descriptions of final-state interactions (FSI) in the inclusive scattering are compared. In the relativistic Green’s function (RGF) model FSI are described consistently with the exclusive scattering using a complex optical potential. In the relativistic mean field (RMF) model FSI are described by the same RMF potential which gives the bound states. The results of the models are compared for electron and neutrino scattering and, for neutrino scattering, with the recently measured charged-current QE (CCQE) MiniBooNE cross sections.

Measurement of the neutrino component of an antineutrino beam observed by a nonmagnetized detector

Two independent methods are employed to measure the neutrino flux of the anti-neutrino-mode beam observed by the MiniBooNE detector. The first method compares data to simulated event rates in a high purity $\numu$ induced charged-current single $\pip$ (CC1$\pip$) sample while the second exploits the difference between the angular distributions of muons created in $\numu$ and $\numub$ charged-current quasi-elastic (CCQE) interactions. The results from both analyses indicate the prediction of the neutrino flux component of the pre-dominately anti-neutrino beam is over-estimated - the CC1$\pip$ analysis indicates the predicted $\numu$ flux should be scaled by $0.76 \pm 0.11$, while the CCQE angular fit yields $0.65 \pm 0.23$. The energy spectrum of the flux prediction is checked by repeating the analyses in bins of reconstructed neutrino energy, and the results show that the spectral shape is well modeled. These analyses are a demonstration of techniques for measuring the neutrino contamination of anti-neutrino beams observed by future non-magnetized detectors.

The ArgoNeuT LAr-TPC: A dedicated experiment for neutrino cross section measurement at FNAL

ArgoNeuT, a Liquid Argon Time Projection Chamber (LAr-TPC), has recently collected thousands of neutrino and anti-neutrino events between 0.1 and 10 GeV in the NuMI beamline at Fermilab (FNAL). Among other issues, the experiment will measure the cross section of the neutrino and anti-neutrino Charged Current Quasi-Elastic (CCQE) interaction on Ar target and analyze the vertex activity associated with such events. Outcomes from the reconstruction of the events provide the main subject of this paper.