Neutrino-induced single-pion production (SPP) provides an important contribution to neutrino-nucleus interactions, ranging from intermediate to high energies. There exists a good number of low-energy ...models in the literature to describe the neutrino production of pions in the region around the Delta resonance. Those models consider only lowest-order interaction terms and, therefore, fail in the high-energy region (pion-nucleon invariant masses, W≳2 GeV). Our goal is to develop a model for electroweak SPP off the nucleon, which is applicable to the entire energy range of interest for present and future accelerator-based neutrino-oscillation experiments. We start with the low-energy model of E. Hernández, J. Nieves, and M. Valverde, Phys. Rev. D 76, 033005 (2007)., which includes resonant contributions and background terms derived from the pion-nucleon Lagrangian of chiral-perturbation theory S. Scherer and M. R. Schindler, A Primer for Chiral Perturbation Theory (Springer, Berlin, 2012), p. 1.. Then, from the background contributions, we build a high-energy model using a Regge approach. The low- and high-energy models are combined, in a phenomenological way, into a hybrid model. The hybrid model is identical to the low-energy model in the low-W region, but, for W>2 GeV, it implements the desired high-energy behavior dictated by Regge theory. We have tested the high-energy model by comparing with one-pion production data from electron and neutrino reactions. The hybrid model is compared with electron-proton scattering data, with neutrino SPP data and with the predictions of the NuWro Monte Carlo event generator. Our model is able to provide satisfactory predictions of the electroweak one-pion production cross section from pion threshold to high W. Further investigation and more data are needed to better understand the mechanisms playing a role in the electroweak SPP process in the high-W region, in particular, those involving the axial current contributions.
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The hybrid model for electroweak single-pion production (SPP) off the nucleon, presented by González-Jiménez et al. Phys. Rev. D 95, 113007 (2017), is extended here to the case of incoherent ...pion-production on the nucleus. Combining a low-energy model with a Regge approach, this model provides valid predictions in the entire energy region of interest for current and future accelerator-based neutrino-oscillation experiments. The relativistic mean-field model is used for the description of the bound nucleons while the outgoing hadrons are considered as plane waves. This approach, known as the relativistic plane-wave impulse approximation (RPWIA), is a first step towards the development of more sophisticated models; it is also a test of our current understanding of the elementary reaction. We focus on the charged-current ν(ν¯)-nucleus interaction at MiniBooNE and MINERvA kinematics. The effect on the cross sections of the final-state interactions, which affect the outgoing hadrons on their way out of the nucleus, is judged by comparing our results with those from the NuWro Monte Carlo event generator. We find that the hybrid-RPWIA predictions largely underestimate the MiniBooNE data. In the case of MINERvA, our results fall below the ν-induced 1π0 production data, while a better agreement is found for ν-induced 1π+ and ν¯-induced 1π0 production.
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Pion production is a significant component of the signal in accelerator-based neutrino experiments. Over the last years, the MiniBooNE, T2K, and MINERvA collaborations have reported a substantial ...amount of data on (anti)neutrino-induced pion production on the nucleus. However, a comprehensive and consistent description of the whole data set is still missing. We aim at improving the current understanding of neutrino-induced pion production on the nucleus. To this end, the comparison of experimental data with theoretical predictions, preferably based on microscopic models, is essential to disentangle the different reaction mechanisms involved in the process. To describe single-pion production, we use a hybrid model that combines low- and a high-energy approaches. The low-energy model contains resonances and background terms. At high invariant masses, a high-energy model based on a Regge approach is employed. The model is implemented in the nucleus using the relativistic plane wave impulse approximation (RPWIA). We present a comparison of the hybrid-RPWIA and low-energy model with the recent neutrino-induced charged-current 1π+-production cross section on water reported by T2K. In order to judge the impact of final-state interactions (FSI), we confront our results with those of the nuwro Monte Carlo generator. The hybrid-RPWIA model and nuwro results compare favorably to the data, albeit that FSI are not included in the former. The need of a high-energy model at T2K kinematics is made clear. These results complement our previous work Phys. Rev. D 97, 013004 (2018), in which we compared the models to the MINERvA and MiniBooNE 1π+ data. The hybrid-RPWIA model tends to overpredict both the T2K and MINERvA data in kinematic regions where the largest suppression due to FSI is expected and agrees remarkably well with the data in other kinematic regions. On the contrary, the MiniBooNE data are underpredicted over the whole kinematic range.
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Differences between ν_{e} and ν_{μ} quasielastic cross sections are essential in neutrino oscillation analyses and CP violation searches for experiments such as DUNE and T2HK. The ratio of these is ...however poorly known experimentally and for certain kinematic regions theoretical models give contradictory answers. We use two independent mean-field based models to investigate this ratio using ^{40}Ar and ^{12}C targets. We demonstrate that a proper treatment of the final nucleon's wave function confirms the dominance of ν_{μ} over ν_{e} induced cross sections at forward lepton scattering.
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One of the substantial sources of systematic errors in neutrino oscillation experiments that utilize neutrinos from accelerator sources stems from a lack of precision in modeling single-pion ...production (SPP). Oscillation analyses rely on Monte Carlo event generators (MC), providing theoretical predictions of neutrino interactions on nuclear targets. Pions produced in these processes provide a significant fraction of oscillation signal and background on both elementary scattering and detector simulation levels. Thus, it is of critical importance to develop techniques that will allow us to accommodate state-of-the-art theoretical models describing SPP into MCs. In this work, we investigate various algorithms to implement single-pion production models in Monte Carlo event generators. Based on comparison studies, we propose a novel implementation strategy that combines satisfactory efficiency with high precision in reproducing details of theoretical models predictions, including pion angular distributions. The proposed implementation is model-independent, thereby providing a framework that can include any model for SPP. We have tested the new algorithm with the Ghent low energy model for single-pion production implemented in the NuWro Monte Carlo event generator.
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Here, we show that the quasielastic (QE) response calculated with the superscaling approach (SuSAv2) model, that relies on the scaling phenomenon observed in the analysis of ($\mathcal{e,e}'$) data ...and on the relativistic mean-field theory, is very similar to that from a relativistic distorted-wave impulse approximation model when only the real part of the optical potentials is employed. The coincidence between the results from these two completely independent approaches, which satisfactorily agree with the inclusive data, reinforces the reliability of the quasielastic predictions stemming from both models and sets constraints for the QE response. We also study the low-energy and momentum-transfer region of the inclusive response by confronting the results of the relativistic mean-field model with those of the Hartree-Fock continuum random-phase approximation model, which accounts for nuclear long-range correlations. Finally, we present a comparison of our results with the recent Jefferson Laboratory (JLab) ($\mathcal{e,e}'$) data for argon, titanium, and carbon, finding good agreement with the three data sets.
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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, {\it 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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