arXiv subjects

M. B. Barbaro

Publications and source records attributed to M. B. Barbaro.

At least 19 recordsLinked to original sources

arXiv2026

Relativistic distorted-wave analysis of the missing-energy spectrum measured with monochromatic $ν_μ$-$^{12}$C interactions at JSNS$^{2}$

Recently, the JSNS$^2$ collaboration measured for the first time the missing-energy distribution of $^{12}$C using a monochromatic neutrino beam coming from kaon decays at rest. In this work we present the results of an analysis of this spectrum using the relativistic distorted-wave approach. A new parameterization of the spectral function for neutrons in $^{12}$C, which incorporates detailed information from $\left(e,e'p\right)$ experiments with high missing-energy resolution has been used. The role of the recoil of the residual nucleus, final-state interactions, and neutrino event generators are discussed.

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arXiv2025

Meson-Exchange Currents in Quasielastic Charged-Current Neutrino Reactions with Single-Nucleon Knockout

The effect of meson-exchange currents on charged-current quasielastic neutrino scattering with single-nucleon emission is computed and analyzed within the relativistic Fermi gas model. This contribution arises primarily from the interference between one-body and two-body currents, where the two-body operator excites a 1p1h state in the presence of a second, spectator nucleon. The results obtained show a reduction of the vector, axial and vector-axial transverse response functions and, consequently, a decrease in the total neutrino cross section. In addition to a comparison with the non-relativistic limit, other models are also explored, such as the relativistic mean field model for nuclear matter and the superscaling analysis with relativistic effective mass, both of which yield qualitatively similar results.

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arXiv2025

Progress on Constraining the Strange Quark Contribution to the Nucleon Spin

We report on a global fit of neutral-current elastic (NCE) neutrino-scattering data and parity-violating electron-scattering (PVES) data with the goal of determining the strange quark contribution to the vector and axial form factors of the proton. Knowledge of the strangeness contribution to the axial form factor, $G_A^s(Q^2)$, at low $Q^2$ will reveal the strange quark contribution to the nucleon spin, as $G_A^s(Q^2=0)=Δs$. Previous fits [1,2] of this form included data from a variety of PVES experiments (PVA4, HAPPEx, G0, SAMPLE) and the NCE neutrino and anti-neutrino data from BNL E734. These fits did not constrain $G_A^s(Q^2)$ at low $Q^2$ very well because there was no NCE data for $Q^2<0.45$ GeV$^2$. Our new fit includes for the first time MiniBooNE NCE data from both neutrino and anti-neutrino scattering; this experiment used a hydrocarbon target and so a model of the neutrino interaction with the carbon nucleus was required. Three different nuclear models have been employed; a relativistic Fermi gas (RFG) model, the SuperScaling Approximation (SuSA) model, and a spectral function (SF) model [3]. We find a tremendous improvement in the constraint of $G_A^s(Q^2)$ at low $Q^2$ compared to previous work, although more data is needed from NCE measurements that focus on exclusive single-proton final states, for example from MicroBooNE [4]. This work has been published in Physical Review D [5]. [1] S.F. Pate, D. McKee, V. Papavassiliou, Phys. Rev. C78, 015207 (2008) [2] S.F. Pate, D. Trujillo, EPJ Web of Conferences 66, 06018 (2014) [3] C. Giusti and M.V. Ivanov, J. Phys. G: Nucl. Part. Phys. 47 024001 (2020) [4] L. Ren, NuFact 2021, PoS, 402, 205 (2022), 10.22323/1.402.0205 [5] S.F. Pate et al., Phys. Rev. D 109, 093001, 2024

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arXiv2025

MEC-induced two-nucleon emission in neutrino-nucleus scattering

Meson-exchange currents (MEC) play a crucial role in the nuclear response to a leptonic probe, inducing the emission of two nucleons, the so-called 2p2h excitations. Here we report the results of our recent work \cite{Belocchi:2025eix}, in which we evaluated the 2p2h contribution to the $(ν_μ,μ^-p)$ neutrino cross section off a carbon target, which involves the simultaneous detection the outgoing muon and a proton in the final state. This process has recently been measured in long-baseline neutrino experiments, but no truly microscopic calculation for the 2p2h channel existed to be compared with these data until now. The calculation employs fully relativistic two-body currents and is carried out within the Relativistic Fermi Gas framework. It provides a generalization to the weak sector of the electromagnetic inclusive model developed in Ref.~\cite{DePace:2003spn} and an extension of the calculation to enable semi-inclusive predictions. A selection of our results for the semi-inclusive cross section versus the emitted proton variables is presented, both at fixed neutrino energy and folded with the T2K muon-neutrino flux.

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arXiv2025

Determination of the moments of the proton charge density

A global analysis of proton electric form factor experimental data from Rosenbluth separation and low squared four-momentum transfer experiments is discussed for the evaluation of the spatial moments of the proton charge density based on the recently published integral method. Specific attention is paid to the evaluation of the systematic errors of the method, particularly the sensitivity to the choice of the mathematical expression of the form factor fitting function. Within this comprehensive analysis of proton electric form factor data, the moments of the proton charge density are determined for integer order moments, particularly: $\langle r^2 \rangle$=0.694(09)$_{Sta.}$(16)$_{Sys.}$~fm$^2$, $\langle r^3 \rangle$=0.870(46)$_{Sta.}$(80)$_{Sys.}$~fm$^3$, and $\langle r^4 \rangle$=1.47(25)$_{Sta.}$(45)$_{Sys.}$~fm$^4$.

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arXiv2024

Analysis of NOvA and MicroBooNE charged-current inclusive neutrino measurements within the SuSAv2 framework

In this work we compare the SuSAv2 model, based on the superscaling phenomenon and the relativistic mean field theory, with charged-current inclusive neutrino cross sections from the NOvA and MicroBooNE experiments, whose targets are composed primarily by 12 C and 40 Ar, respectively. The neutrino energy in these experiments covers a kinematic range from tens of MeV to roughly 20 GeV. Thus, we consider the different reaction mechanisms that contribute significantly to these kinematics, namely quasielastic, two-particle two-hole meson exchange currents, resonances and deep inelastic scattering contributions.

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arXiv2024

Global Fit of Electron and Neutrino Elastic Scattering Data to Determine the Strange Quark Contribution to the Vector and Axial Form Factors of the Nucleon

We present a global fit of neutral-current elastic (NCE) neutrino-scattering data and parity-violating electron-scattering (PVES) data with the goal of determining the strange quark contribution to the vector and axial form factors of the proton. Previous fits of this form included data from a variety of PVES experiments (PVA4, HAPPEx, G0, SAMPLE) and the NCE neutrino and anti-neutrino data from BNL E734. These fits did not constrain the strangeness contribution to the axial form factor $G_A^s(Q^2)$ at low $Q^2$ very well because there was no NCE data for $Q^2<0.45$ GeV$^2$. Our new fit includes for the first time MiniBooNE NCE data from both neutrino and anti-neutrino scattering; this experiment used a hydrocarbon target and so a model of the neutrino interaction with the carbon nucleus was required. Three different nuclear models have been employed: a relativistic Fermi gas model, the SuperScaling Approximation model, and a spectral function model. We find a tremendous improvement in the constraint of $G_A^s(Q^2)$ at low $Q^2$ compared to previous work, although more data is needed from NCE measurements that focus on exclusive single-proton final states, for example from MicroBooNE.

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arXiv2024

New model comparison for semi-inclusive charged-current electron and muon neutrino scattering by $^{40}$Ar 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 $^{40}$Ar 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.

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arXiv2023

Determination of the moments of the proton charge density: is there a proton radius puzzle?

The charge radius of the proton can be determined using two different kinds of experiments: the spectroscopy technique, measuring the hyperfine structure of hydrogen atoms, and the scattering technique, deducing the radius from elastic lepton scattering off a proton target. These two methods lead to quite different results, a discrepancy known as the "proton radius puzzle ". To shed light on this problem, we have proposed a novel method for the determination of spatial moments from densities expressed in the momentum space. This method provides a direct access not only to the second order moment, directly related to the proton radius, but to all moments of any real order larger than -3. The method is applied to the global analysis of proton electric form factor experimental data from Rosenbluth separation and low-$Q^2$ experiments, paying specific attention to the evaluation of the systematic errors. Within this analysis, the integer order moments of the proton charge density are evaluated, the moment of second order leading to a new determination of the proton charge radius.

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arXiv2023

Meson-exchange currents in quasielastic electron scattering in a generalized superscaling approach

We present a model that incorporates the effect of two-body currents in quasielastic electron-nucleus scattering within the framework of a consistent superscaling formalism. This is achieved by defining an averaged single-nucleon hadronic tensor based on the 1p1h matrix element of the one-body current plus meson-exchange currents (MEC). The consistent treatment of one- and two-body currents in our model enables the calculation of exchange current effects in the kinematical region where the Fermi gas response is zero, but not the scaling function. The effect of MEC is consistently taken into account when extracting the phenomenological scaling function from electron scattering data. With this model, we investigate the effect of MEC on the response functions taking into account the effective mass of the nucleon, and examine the consequences it has on the inclusive $(e,e')$ cross section. We find that 1p1h MEC deplete the quasielastic transverse response, while they not alter significantly the scaling behavior of (e,e') data.

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arXiv2023

Superscaling in the resonance region for neutrino-nucleus scattering: The SuSAv2-DCC model

In this work the SuSAv2 and dynamical coupled-channels (DCC) models have been combined and tested in the inelastic regime for electron and neutrino reactions on nuclei. The DCC model, an approach to study baryon resonances through electron and neutrino induced meson production reactions, has been implemented for the first time in the SuSAv2-inelastic model to analyze the resonance region. Within this framework, we also present a novel description about other inelasticities in the resonance region (SoftDIS). The outcomes of these approaches are firstly benchmarked against (e,e') data on 12C. The description is thus extended to the study of neutrino-nucleus inclusive cross sections on 12C and 40Ar and compared with data from the T2K, MicroBooNE, ArgoNEUT and MINERvA experiments, thus covering a wide kinematical range.

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arXiv2022

Final state interactions in semi-inclusive neutrino-nucleus scattering: Application to T2K and MINER$ν$A experiments

We present a complete comparison of semi-inclusive $ν_μ$-$^{12}$C cross-section measurements by T2K and MINER$ν$A collaborations with the predictions from the SuSAv2-MEC model implemented in the neutrino-nucleus event generator GENIE and an unfactorized approach based on the relativistic distorted wave impulse approximation (RDWIA). Results, that include cross sections as function of the final muon and proton kinematics and correlations between both, show that the agreement with data obtained by the RDWIA approach, that accounts for final-state interactions, matches or improves GENIE-SuSAv2 predictions for very forward angles where scaling violations are relevant.

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arXiv2022

The SuSAv2 model for inelastic neutrino-nucleus scattering

The susperscaling model SuSAv2, already available for charged-current neutrino-nucleus cross sections in the quasielastic region, is extended to the full inelastic regime. In the model the resonance production and deep inelastic reactions are described through the extension to the neutrino sector of the SuSAv2 inelastic model developed for ($e,e'$) reactions, which combines phenomenological structure functions with a nuclear scaling function. This work also compares two different descriptions of the $Δ$ resonance region, one based on a global scaling function for the full inelastic spectrum and the other on a semi-phenomenological $Δ$ scaling function extracted from ($e,e'$) data for this specific region and updated with respect to previous work. The results of the model are tested against ($e,e'$) data on $^{12}$C, $^{16}$O, $^{40}$Ca and $^{40}$Ar and applied to the study of the charged current inclusive neutrino cross-section on $^{12}$C and $^{40}$Ar measured by the T2K, MicroBooNE, ArgoNEUT and MINERvA experiments, thus covering several kinematical regions.

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arXiv2021

Theoretical description of semi-inclusive T2K, Miner$ν$A and MicroBooNE neutrino-nucleus data in the relativistic plane wave impulse approximation

We present the results of semi-inclusive neutrino-nucleus cross sections within the plane wave impulse approximation (PWIA) for three nuclear models: relativistic Fermi gas (RFG), independent-particle shell model (IPSM) and natural orbital shell model (NO) in comparison with the available CC0$π$ measurements from the T2K, MINER$ν$A and MicroBooNE collaborations where a muon and at least one proton are detected in the final state. Results are presented as a function of the momenta and angles of the final particles, as well as in terms of the imbalances between proton and muon kinematics. The analysis reveals that contributions beyond PWIA are crucial to explain the experimental measurements and that the study of correlations between final-state proton and muon kinematics can provide valuable information on relevant nuclear effects such as the Fermi motion and final state interactions.

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arXiv2021

Neutrino-Nucleus scattering in the SuSA model

The Super-Scaling Approach (SuSA) model, based on the analogies between electron and neutrino interactions with nuclei, is reviewed and its application to the description of neutrino-nucleus scattering is presented. The contribution of both one- and two-body relativistic currents is considered. A selection of results is presented where theoretical predictions are compared with cross section measurements from the main ongoing neutrino oscillation experiments.

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arXiv2021

New evaluation of axial nucleon form factor from electron- and neutrino-scattering data and impact on neutrino-nucleus cross-section

A joint fit to neutrino-nucleon scattering and pion electroproduction data is performed to evaluate the nucleon axial form factor in the two-component model consisting of a three-quark intrinsic structure surrounded by a meson cloud. Further constrains on the model are obtained by re-evaluating the electromagnetic form factor using electron scattering data. The results of the axial form factor show sizable differences with respect to the widely used dipole model. The impact of such changes on the Charged-Current Quasi-Elastic neutrino-nucleus cross-section is evaluated in the SuSAv2 nuclear model, based on the Relativistic Mean Field and including the contribution of two-body currents. How the different parametrizations of the axial form factor affect the cross-section prediction is assessed in full details and comparisons to recent T2K and MINERvA data are presented.

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arXiv2021

Neutrino energy reconstruction from semi-inclusive samples

We study neutrino-nucleus charged-current reactions on finite nuclei for the situation in which an outgoing muon and a proton are detected in coincidence, i.e., we focus on semi-inclusive cross sections. We limit our attention to one-body current interactions (quasielastic scattering) and assess the impact of different nuclear effects in the determination of the neutrino energy. We identify the regions in phase space where the neutrino energy can be reconstructed relatively well, and study whether the cross section in those regions is significant. Our results indicate that it is possible to filter more than 50% of all events according to the muon and proton kinematics, so that for the DUNE and T2K fluxes the neutrino energy can be determined with an uncertainty of less than 1% and 3%, respectively. Furthermore, we find that the reconstructed neutrino energy does not depend strongly on how one treats the final-state interactions and is not much affected by the description of the initial state. On the other hand, the estimations of the uncertainty on the neutrino energy show important sensitivity to the modeling of the initial state.

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arXiv2020

Semi-inclusive charged-current neutrino-nucleus cross sections in the relativistic plane wave impulse approximation

Neutrino-nucleus quasielastic scattering is studied in the plane wave impulse approximation for three nuclear models: the relativistic Fermi gas (RFG), the independent-particle shell model (IPSM) and the natural orbitals (NO) model with Lorentzian dependence of the excitation energy. A complete study of the kinematics of the semi-inclusive process and the associated cross sections are presented and discussed for 40 Ar and 12 C. Inclusive cross sections are also obtained by integrating the semi-inclusive expressions over the outgoing hadron. Results are consistent with previous studies restricted to the inclusive channel. In particular, a comparison with the analytical results for the RFG model is performed. Explicit expressions for the hadronic tensor and the 10 semi-inclusive nuclear responses are given. Theoretical predictions are compared with semi-inclusive experimental data from T2K experiment.

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