JLab spectral functions of argon in NuWro and their implications for MicroBooNE

Published in Physical Review D, 2024

The Short-Baseline Neutrino program in Fermilab aims to resolve the nature of the low-energy excess events observed in LSND and MiniBooNE, and analyze with unprecedented precision neutrino interactions with argon. These studies require a reliable estimate of neutrino cross sections, in particular for charged current quasielastic scattering (CCQE). Here, we report updates of the nuwro Monte Carlo generator that, most notably, bring the state-of-the-art spectral functions to model the ground state properties of the argon nucleus, and improve the accuracy of the cross sections at low energies by accounting for the effects of the nuclear Coulomb potential. We discuss these developments in the context of electron and neutrino interactions, by comparing updated nuwro predictions to experimental data from Jefferson Laboratory Hall A and MicroBooNE. The MicroBooNE CCQE-dominated data are described with the χ2 per degree of freedom of 0.7, compared with 1.0 in the local Fermi gas model. The largest improvement is observed for the angular distributions of the produced protons, where the χ2 reduces nearly by half. Being obtained using the axial form factor parametrization from MINERvA, our results indicate a consistency between the CCQE measurements in MINERvA and MicroBooNE.

Recommended citation: Rwik Dharmapal Banerjee, Artur M. Ankowski, Krzysztof M. Graczyk, Beata E. Kowal, Hemant Prasad, Jan T. Sobczyk, Phys. Rev. D 109, 073004 https://journals.aps.org/prd/abstract/10.1103/PhysRevD.109.073004

Empirical fits to inclusive electron-carbon scattering data obtained by deep-learning methods

Published in arxiv, 2024

Employing the neural network framework, we obtain empirical fits to the electron-scattering cross section for carbon over a broad kinematic region, extending from the quasielastic peak, through resonance excitation, to the onset of deep-inelastic scattering. We consider two different methods of obtaining such model-independent parametrizations and the corresponding uncertainties: based on the NNPDF approach [J. High Energy Phys. 2002, 062], and on the Monte Carlo dropout. In our analysis, the χ2 function defines the loss function, including point-to-point uncertainties and considering the systematic normalization uncertainties for each independent set of measurements. Our statistical approaches lead to fits of comparable quality and similar uncertainties of the order of 7% and 12% for the first and the second approaches, respectively. To test these models, we compare their predictions to a~test dataset, excluded from the training process, a~dataset lying beyond the covered kinematic region, and theoretical predictions obtained within the spectral function approach. The predictions of both models agree with experimental measurements and the theoretical predictions. However, the first statistical approach shows better interpolation and extrapolation abilities than the one based on the dropout algorithm.

Recommended citation: Beata E. Kowal, Krzysztof M. Graczyk, Rwik Dharmapal Banerjee, Artur M. Ankowski, Hemant Prasad, Jan T. Sobczyk, arXiv:2312.17298 https://arxiv.org/abs/arXiv:2312.17298

Neutral current neutrino and antineutrino scattering off the polarized nucleon

Published in Physical Review D, 2023

The elastic and inelastic neutral current Nu (Anit Nu) scattering off the polarized nucleon is discussed. The inelastic scattering concerns the single-pion production process. We show that the spin asymmetries measurement can help to distinguish between neutrino and antineutrino neutral current scattering processes. The spin asymmetries also encode information about a type of target. Eventually, detailed studies of the inelastic spin asymmetries can improve understanding of the resonant-nonresonant pion production mechanism.

Recommended citation: Krzysztof M. Graczyk, Beata E. Kowal, Phys.Rev.D 108, 093002 (2023) https://journals.aps.org/prd/abstract/10.1103/PhysRevD.108.093002

Bayesian Reasoning for Physics Informed Neural Networks

Published in arxiv, 2023

Physics informed neural network (PINN) approach in Bayesian formulation is presented. We adopt the Bayesian neural network framework formulated by MacKay (Neural Computation 4 (3) (1992) 448). The posterior densities are obtained from Laplace approximation. For each model (fit), the so-called evidence is computed. It is a measure that classifies the hypothesis. The most optimal solution has the maximal value of the evidence. The Bayesian framework allows us to control the impact of the boundary contribution to the total loss. Indeed, the relative weights of loss components are fine-tuned by the Bayesian algorithm. We solve heat, wave, and Burgers equations. The obtained results are in good agreement with the exact solutions. All solutions are provided with the uncertainties computed within the Bayesian framework.

Recommended citation: Krzysztof M. Graczyk, Kornel Witkowski, arxiv:2308.13222 https://arxiv.org/abs/2308.13222

Deep learning for diffusion in porous media

Published in Scientific Reports, 2023

We adopt convolutional neural networks (CNN) to predict the basic properties of the porous media. Two different media types are considered: one mimics the sand packings, and the other mimics the systems derived from the extracellular space of biological tissues. The Lattice Boltzmann Method is used to obtain the labeled data necessary for performing supervised learning. We distinguish two tasks. In the first, networks based on the analysis of the system’s geometry predict porosity and effective diffusion coefficient. In the second, networks reconstruct the concentration map. In the first task, we propose two types of CNN models: the C-Net and the encoder part of the U-Net. Both networks are modified by adding a self-normalization module [Graczyk et al. in Sci Rep 12, 10583 (2022)]. The models predict with reasonable accuracy but only within the data type, they are trained on. For instance, the model trained on sand packings-like samples overshoots or undershoots for biological-like samples. In the second task, we propose the usage of the U-Net architecture. It accurately reconstructs the concentration fields. In contrast to the first task, the network trained on one data type works well for the other. For instance, the model trained on sand packings-like samples works perfectly on biological-like samples. Eventually, for both types of the data, we fit exponents in the Archie’s law to find tortuosity that is used to describe the dependence of the effective diffusion on porosity.

Recommended citation: Krzysztof M. Graczyk, Dawid Strzelczyk, Maciej Matyka, Sci Rep 13, 9769 (2023) https://www.nature.com/articles/s41598-023-36466-w

Resonant Enlargements of the Poincaré/AdS (Super)Algebras

Published in Acta Physica Polonica B, Proceedings, Contribution to the proceedings of The 8th Conference of the Polish Society on Relativity 2022, Warsaw (Poland), 2023

Applying an efficient pattern-based computational method of generating the so-called resonating algebraic structures results in a broad class of the new Lie (super)algebras. Those structures inherit the AdS base (anti) commutation pattern and can be treated as the enlargements of the Poincaré or Anti-de-Sitter (super)algebras. Obtained superalgebras are rooted in the Semigroup expansion method and Maxwell and Soroka–Soroka algebras, spanned by the Lorentz generator Jab, translations Pa, and additional Lorentz-like generator Zab. Considered configurations include cases up to two fermionic supercharges Qα​ and offer interesting modifications to the gauge (super)gravity theories.

Recommended citation: R. Durka, K. M. Graczyk, Acta Phys.Polon.Supp. 16 (2023) 6, 11 https://www.actaphys.uj.edu.pl/fulltext?series=Sup&vol=16&aid=6-A11

N=2 resonant superalgebra for supergravity

Published in Physics Letters B, 2022

We present new superalgebra for N=2 D=3,4 supergravity theory endowed with the U(1) generator. The superalgebra is rooted in the so-called Soroka-Soroka algebra and spanned by the Lorentz Jab and Lorentz-like Zab, translation Pa and T generators, as well as two supercharges QIα. We construct a corresponding 3D Chern-Simons supergravity realization of the superalgebra and discuss its relevance.

Recommended citation: Remigiusz Durka, Krzysztof M. Graczyk, Phys. Lett. B 833, 137366 (2022) https://doi.org/10.1016/j.physletb.2022.137366

Resonant superalgebras for supergravity

Published in European Physical Journal C, 2022

Considering supergravity theory is a natural step in the development of gravity models. This paper follows the algebraic path and constructs possible extensions of the Poincare and Anti-de-Sitter algebras, which inherit their basic commutation structure. Previously achieved results of this type are fragmentary and show only a limited fraction of possible algebraic realizations. Our paper presents the newly obtained symmetry algebras, evaluated within an efficient pattern-based computational method of generating the so-called resonating algebraic structures. These supersymmetric extensions of algebras, going beyond the Poincare and Anti-de Sitter ones, contain additional bosonic generators $Z_{ab}$ (Lorentz-like), and $U_a$ (translational-like) added to the standard Lorentz generator $J_{ab}$ and translation generator $P_{a}$. Our analysis includes all cases up to two fermionic supercharges, $Q_{\alpha}$ and $Y_{\alpha}$. The delivered plethora of superalgebras includes few past results and offers a vastness of new examples. The list of the cases is complete and contains all superalgebras up to two of Lorentz-like, translation-like, and supercharge-like generators $(JP+Q)+(ZU+Y)=JPZU+QY$. In the latter class, among $667$ founded superalgebras, the $264$ are suitable for direct supergravity construction. For each of them, one can construct a unique supergravity model defined by the Lagrangian. As an example, we consider one of the algebra configurations and provide its Lagrangian realization.

Recommended citation: Remigiusz Durka, Krzysztof M. Graczyk, Eur. Phys. J. C 82, 254 (2022) https://doi.org/10.1140/epjc/s10052-022-10156-9

Self-Normalized Density Map (SNDM) for Counting Microbiological Objects

Published in Scientific Reports, 2022

The statistical properties of the density map (DM) approach to counting microbiological objects on images are studied in detail. The DM is given by U2-Net. Two statistical methods for deep neural networks are utilized: the bootstrap and the Monte Carlo (MC) dropout. The detailed analysis of the uncertainties for the DM predictions leads to a deeper understanding of the DM model s deficiencies. Based on our investigation, we propose a self-normalization module in the network. The improved network model, called Self-Normalized Density Map (SNDM), can correct its output density map by itself to accurately predict the total number of objects in the image. The SNDM architecture outperforms the original model. Moreover, both statistical frameworks – bootstrap and MC dropout – have consistent statistical results for SNDM, which were not observed in the original model.

Recommended citation: Krzysztof M. Graczyk, Jarosław Pawłowski, Sylwia Majchrowska, Tomasz Golan, Sci Rep 12, 10583 (2022) https://rdcu.be/cQbPy

Model dependence of the polarization asymmetries in weak pion production off the nucleon

Published in Physical Review D, 2021

The work presents the study of the polarization observables in the single pion production (SPP) induced by the interaction of the muon neutrino (antineutrino) with nucleons. The SPP cross sections and spin asymmetries are computed within two phenomenological models. One is based on the nonlinear sigma model [E. Hernandez, J. Nieves, and M. Valverde, Phys. Rev. D 76, 033005 (2007)] and the other has origin in the linear sigma model [G. L. Fogli and G. Nardulli, Nucl. Phys. B160, 116 (1979)]. First, we show that the final nucleon polarization and target spin asymmetries are good observables to obtain information about the C5A axial form factor. Second, we demonstrate that the nucleon polarization and the target spin asymmetries are sensitive to the relative phase between resonance and nonresonance amplitudes. We conclude that the polarization of the final nucleon and the target spin asymmetry are promising observables for testing SPP models, including studies of the axial content of Δ(1232) resonance and unitarization procedures.

Recommended citation: Krzysztof M. Graczyk, Beata E. Kowal, Phys. Rev. D 104, 033005 (2021) https://journals.aps.org/prd/abstract/10.1103/PhysRevD.104.033005

Predicting porosity, permeability, and tortuosity of porous media from images by deep learning

Published in Scientific Reports, 2020

Convolutional neural networks (CNN) are utilized to encode the relation between initial configurations of obstacles and three fundamental quantities in porous media: porosity (𝜑), permeability (k), and tortuosity (T). The two-dimensional systems with obstacles are considered. The fluid flow through a porous medium is simulated with the lattice Boltzmann method. The analysis has been performed for the systems with 𝜑∈(0.37,0.99) which covers five orders of magnitude a span for permeability 𝑘∈(0.78,2.1×105) and tortuosity 𝑇∈(1.03,2.74). It is shown that the CNNs can be used to predict the porosity, permeability, and tortuosity with good accuracy. With the usage of the CNN models, the relation between T and 𝜑 has been obtained and compared with the empirical estimate.

Recommended citation: Krzysztof M. Graczyk, Maciej Matyka, Sci Rep 10, 21488 (2020) https://doi.org/10.1038/s41598-020-78415-x

Spin asymmetries in quasielastic charged current neutrino-nucleon scattering

Published in Physical Review D, 2020

The work concerns the quasielastic charged current neutrino-neutron and antineutrino-proton interactions. Single, double, and triple spin asymmetries are computed and analyzed. The spin asymmetries are sensitive to the axial form factor of the nucleon. In particular, the target-recoil double spin asymmetry and the lepton-target-recoil triple spin asymmetry depend strongly on the axial form factor of the nucleon. Indeed, the sign and shape of these components depend on the axial mass parameter. All the asymmetries, except the lepton polarization, are observables well suited to study the nonstandard interactions described by the second-class current contribution.

Recommended citation: Krzysztof M. Graczyk and Beata E. Kowal, Phys. Rev. D 101, 073002 (2020) https://journals.aps.org/prd/abstract/10.1103/PhysRevD.101.073002

Nucleon axial form factor from a Bayesian neural-network analysis of neutrino-scattering data

Published in Physical Review C, 2019

The Bayesian approach for feedforward neural networks has been applied to the extraction of the nucleon axial form factor from the neutrino-deuteron-scattering data measured by the Argonne National Laboratory bubble-chamber experiment. This framework allows to perform a model-independent determination of the axial form factor from data. When the low 0.05<Q2<0.10−GeV2 data are included in the analysis, the resulting axial radius disagrees with available determinations. Furthermore, a large sensitivity to the corrections from the deuteron structure is obtained. In turn, when the low-Q2 region is not taken into account with or without deuteron corrections, no significant deviations from previous determinations have been observed. A more accurate determination of the nucleon axial form factor requires new precise measurements of neutrino-induced quasielastic scattering on hydrogen and deuterium.

Recommended citation: L. Alvarez-Ruso, K.M. Graczyk, E.S. Sala, Phys. Rev. C 99, 025204 (2019). https://doi.org/10.1103/PhysRevC.99.025204

Neural network study of the nucleon axial form-factor

Published in Proceedings of Science, Part of Proceedings, 20th International Workshop on Neutrinos from Accelerators (NuFact18) : Blacksburg, VA, USA, August 13-18, 2018, 2019

We have performed the first Bayesian neural-network analysis of neutrino-deuteron scattering data. The nucleon axial form factor has been extracted from quasielastic scattering data collected by the Argonne National Laboratory (ANL) bubble chamber experiment using a model-independent parametrization. The results are in agreement with previous determinations only when the low 0.05<Q2<0.10~GeV2 region is excluded from the analysis. This suggests that corrections from the deuteron structure may play a crucial role at low Q2, although experimental errors in this kinematic region could have also been underestimated. With new and more precise measurements of neutrino-induced quasielastic scattering on hydrogen and deuterium, the present framework would be readily applicable to unravel the axial structure of the nucleon.

Recommended citation: L. Alvarez-Ruso, K. Graczyk, E.S. Sala, PoS NuFACT2018 (2019) 101. https://doi.org/10.22323/1.341.0101

Polarization Effects in Neutrino-Nucleon Interactions

Published in Acta Physica Polonica B, Part of Proceedings, 43rd International Conference of Theoretical Physics: Matter to the Deepest, Recent Developments In Physics Of Fundamental Interactions (MTTD2019) : Chorzów/Katowice, Katowice, Poland, September 1-6, 2019, 1771-1780, 2019

Our recent investigations of the spin asymmetry observables in the charged current inelastic and quasielastic neutrino (antineutrino)–nucleon scattering are reviewed. The spin asymmetry observables contain full information about the structure of the electroweak neutrino–nucleon vertex. Hence, they can be used to constrain the cross-section models for the single-pion production in ν-nucleon scattering and they allow to study the axial content of the nucleon and the second class current contribution to the quasielastic scattering amplitudes.

Recommended citation: K. M. Graczyk, B. E. Kowal, Acta Phys.Polon.B 50, 1771 (2019) https://www.actaphys.uj.edu.pl/index_n.php?I=R&V=50&N=11#1771

Spin asymmetry in single pion production induced by weak interactions of neutrinos with polarized nucleons

Published in Physical Review D, 2019

The single pion production (SPP) in the charged-current neutrino (antineutrino) scattering off the polarized nucleon is discussed. The spin asymmetry is predicted within two approaches. The spin polarizations of the target nucleon that are longitudinal and perpendicular to the neutrino momentum are considered. It is shown, in several examples, that information about the SPP dynamics coming from the spin asymmetry is complementary to information obtained from measurements of spin averaged cross section. Indeed, the spin asymmetry is sensitive to the nonresonance background description of the SPP model. For the normal polarization of the target, the spin asymmetry is given by the interference between the resonance and the nonresonance contributions.

Recommended citation: K. M. Graczyk, B. E. Kowal, Phys. Rev. D 99, 053002 (2019) https://journals.aps.org/prd/abstract/10.1103/PhysRevD.99.053002

Single pion production in neutrino-nucleon scattering studied with FORM package

Published in Proceedings of student poster session of the VII International Pontecorvo Neutrino Physics School (Prague, Czech Republic, August 20 - September 1, 2017), edited by F. Simkovic, - Dubna: JINR, ISBN 978-5-9530-0484-8, 2019

Two models for the single pion production induced by interactions of the neutrinos with the nucleons are studied. The nonresonant background contribution is a subject of analysis. It is shown that the normal component of the polarization of the charged lepton is sensitive on the nonresonant background contribution. It is also demonstrated that the FORM language can be utilized to evaluate all necessary transition matrix elements and the single pion production cross sections.

Recommended citation: Beata E. Kowal, Krzysztof M. Graczyk, Proceedings of student poster session of the VII International Pontecorvo Neutrino Physics School (Prague, Czech Republic, August 20 - September 1, 2017), edited by F. Simkovic, - Dubna: JINR, ISBN 978-5-9530-0484-8 http://theor.jinr.ru/~maw/neutrino17/proceeding_full.pdf

Nonresonant background signal in the polarization transfer in the weak pion production off the nucleon

Published in Neutrino 2018 - XXVIII International Conference on Neutrino Physics and Astrophysics, 4–9 June 2018 — Heidelberg, Germany , 2018

Polarization transfer (PT) observables in the single pion production induced by the charged current neutrino-nucleon interaction are examined within two models. The predictions are made for neutrino energy of the order of 1 GeV as well as for the T2K energy flux. It is demonstrated that the PT observables: the degree of polarization and the polarization components of outgoing fermions are sensitive to the details of the nonresonant background model. It is shown that the normal component of the polarization of the outgoing nucleon and the charged lepton are determined by the interference between the resonant (RES) and nonresonant (NB) amplitudes. Moreover, the sign of the normal component of the polarization of the charged lepton is related to the relative sign between the RES and the NB amplitudes. The presentation is based on: Phys.Rev. D97 (2018) no.1, 013001, and Acta Phys.Polon. B48, 2219 (2017).

Recommended citation: Krzysztof M. Graczyk, Zenodo. https://doi.org/10.5281/zenodo.1301015 (2018) https://zenodo.org/record/1301015

Polarization transfer in weak pion production off the nucleon

Published in Physical Review D, 2018

Polarization transfer (PT) observables in the single pion production induced by the charged current interaction of the neutrino with the nucleon are examined. The polarization components of the final nucleon and the charged lepton are calculated within two models for the pion production. The predictions are made for neutrino energy of the order of 1 GeV as well as for the T2K energy distribution. It is demonstrated that the PT observables, the degree of polarization and the polarization components of outgoing fermions, are sensitive to assumptions about the nonresonant background model. In particular it is shown that the normal components of the polarization of the outgoing nucleon and the lepton are determined by the interference between the resonant (RES) and nonresonant (NB) amplitudes. Moreover, the sign of the normal component of the polarization of the charged lepton is fixed by the relative sign between the RES and the NB amplitudes.

Recommended citation: K. M. Graczyk, B. E. Kowal, Phys.Rev.D 97, 013001 (2018) https://doi.org/10.1103/PhysRevD.97.013001

Single Pion Production Induced by ν-nucleon Interactions

Published in Acta Physica Polonica B, Part of Proceedings, 41st International Conference of Theoretical Physics: Matter to the Deepest : Kroczyce, Poland, September 4-8, 2017, 2017

This article presents a short review of the single pion production (SPP) in the neutrino–nucleon scattering. The attention is focused on the discussion of the main difficulties in modeling the SPP processes. New physical observables, which may constrain the theoretical models, are proposed.

Recommended citation: K. M. Graczyk, B. E. Kowal, Acta Phys.Polon.B48, 2219 (2017) https://www.actaphys.uj.edu.pl/index_n.php?I=R&V=48&N=12#2219

NuWro Monte Carlo generator of neutrino interactions - first electron scattering results

Published in Acta Physica Polonica B, Part of Proceedings, 41st International Conference of Theoretical Physics: Matter to the Deepest : Kroczyce, Poland, September 4-8, 2017, 2015

NuWro Monte Carlo generator of events is presented. It is a numerical environment containing all necessary ingredients to simulate interactions of neutrinos with nucleons and nuclei in realistic experimental situation in wide neutrino energy range. It can be used both for data analysis as well as studies of nuclear effects in neutrino interactions. The first results and functionalities of eWro — module of NuWro dedicated to electron–nucleus scattering — are also presented.

Recommended citation: Jakub Żmuda, Krzysztof M. Graczyk, Cezary Juszczak, Jan T. Sobczyk, Acta Phys.Polon. B46, 2329 (2015) https://www.actaphys.uj.edu.pl/index_n.php?I=R&V=46&N=11#2329

Electroweak single pion production and form factors of the Δ(1232) resonance

Published in AIP, Proceedings, Workshop on Neutrino Interactions, Systematic uncertainties and near detector physics: Session of CETUP* 2014 : Lead/Dead Wood, South Dakota, USA, July 22-31, 2014, 2015

We extend and review our analysis of the nucleon → Δ(1232) transition electroweakform factors from Ref. [1]. New fit of the Δ(1232) vector form factors to electron-proton scattering F2 structure function is introduced as well, leading to results different from the popular parametrization of Ref. [2]. A clear model dependence of the extracted parameters emerges. Fit to neutrino scattering data is performed in all available isospin channels. The resulting axial mass is MAΔ=0.85−0.08+0.09(GeV)and C5A(0)=1.10−0.14+0.15. The latter value is in accordance with Goldberger-Treiman relation as long as the deuteron effects are included.

Recommended citation: Jakub Żmuda, Krzysztof M. Graczyk, AIP Conf.Proc. 1680, 1, 020013 (2015) https://doi.org/10.1063/1.4931872

Zemach moments of the proton from Bayesian inference

Published in Physical Review C, 2015

The first and the third Zemach moments are obtained, ⟨r⟩(2)=1.1108±0.0021 fm and ⟨r3⟩(2)=2.889±0.008 fm3, from the Bayesian analysis of the elastic ep scattering data. The quantitative discussion of the dependence of the results on the parametrization choice is presented and the corresponding systematic uncertainties are estimated—about 0.6% and 1.6% for the first and the third Zemach moments, respectively.

Recommended citation: K. M. Graczyk, C. Juszczak, Phys.Rev.C 91, 045205 (2015) https://doi.org/10.1103/PhysRevC.91.045205

Applications of Neural Networks in Hadron Physics

Published in Joural of Physics G, 2015

The Bayesian approach for the feed-forward neural networks is reviewed. Its potential for usage in hadron physics is discussed. As an example of the application, the study of the two-photon exchange effect is presented. We focus on the model comparison, the estimation of the systematic uncertainties due to the choice of the model and the over-fitting. As an illustration, the predictions of the cross sections ratio ${\rm d}\sigma ({{e}^{+}}p\to {{e}^{+}}p)/{\rm d}\sigma ({{e}^{-}}p\to {{e}^{-}}p)$ are given together with the estimate of the uncertainty due to the parametrization choice.

Recommended citation: K. M. Graczyk, C. Juszczak, J.Phys.G 42, 3, 034019 (2015) https://doi.org/10.1088/0954-3899/42/3/034019

Proton radius from Bayesian inference

Published in Physical Review C, 2014

The methods of Bayesian statistics are used to extract the value of the proton radius from the elastic ep scattering data in a model-independent way. To achieve that goal a large number of parametrizations (equivalent to neural network schemes) are considered and ranked by their conditional probability P(parametrization given data) instead of using the minimal error criterion. As a result the most probable proton radii values (rpE=0.899±0.003 fm, rpM=0.879±0.007 fm) are obtained and systematic error due to freedom in the choice of parametrization is estimated. Correcting the data for the two-photon-exchange effect leads to smaller differences between the extracted values of rpE and rpM. The results disagree with recent muonic atom measurements.

Recommended citation: K. M. Graczyk, C. Juszczak, Phys.Rev.C 90, 054334, 045205 (2014) https://doi.org/10.1103/PhysRevC.90.054334

Electroweak form factors of the Δ(1232) resonance

Published in Physical Review D, 2014

Nucleon→Δ(1232) transition electroweak form factors are discussed in a single pion production model with nonresonant background terms originating from a chiral perturbation theory. Fits to electron-proton scattering F2 as well as neutrino scattering bubble chamber experimental data are performed. Both ν-proton and ν-neutron channel data are discussed in a unified statistical model. A new parametrization of the N→Δ(1232) vector form factors is proposed. In the case of model with deuteron nuclear effects fit to neutrino scattering data gives the axial mass MAΔ=0.85+0.09−0.08  GeV and CA5(0)=1.10+0.15−0.14 in accordance with the Goldberger-Treiman relation. However, the consistency is spoiled when the deuteron effects are omitted; i.e., in this case the fit gives the axial mass MAΔ=0.81+0.09−0.09  GeV and CA5(0)=0.93+0.13−0.13.

Recommended citation: Krzysztof M. Graczyk, Jakub Żmuda, and Jan T. Sobczyk, Phys.Rev.D 90, 9, 093001 (2014) https://doi.org/10.1103/PhysRevD.90.093001

Relevance of Two Boson Exchange Effect in Quasi-Elastic Charged Current Neutrino-Nucleon Interaction

Published in Joural of Physics G, 2014

Two-boson exchange (TBE) correction in νn→l−p and ν¯p→l+n reactions is estimated. The TBE contribution is given by Wγ box diagrams. The calculations are performed for 1 GeV neutrinos and for the MiniBooNE and the T2K energy spectra. The TBE correction to the total cross section is of the order of 2–4% (with respect to the Born contribution) in the case of νe and ν¯e and 1–2% in the case of νμ and ν¯μ .

Recommended citation: K. M. Graczyk, Phys.Lett.B 732, 315 (2014) https://doi.org/10.1016/j.physletb.2014.03.065

Comparison of neural network and hadronic model predictions of the two-photon exchange effect

Published in Physical Review C, 2013

Predictions for the two-photon exchange (TPE) correction to the unpolarized ep elastic cross section, obtained within two different approaches, are confronted and discussed in detail. In the first one the TPE correction is extracted from experimental data by applying the Bayesian neural network statistical framework. In the other the TPE is given by box diagrams, with the nucleon and the P33 resonance as the hadronic intermediate states. Two different form factor parametrizations for both the proton and the P33 resonance are taken into consideration. Proton form factors are obtained from the global fit of the full model (with the TPE correction) to the unpolarized cross-section data. Predictions of the two methods agree well in the intermediate Q2 range of 1–3 GeV2. Above Q2=3 GeV2 the agreement is at the 2σ level. Below Q2=1 GeV2 the consistency between the two approaches is broken. The values of the proton radius extracted within the models are given. In both cases predictions for the VEPP-3 experiment have been obtained and confronted with the preliminary experimental results.

Recommended citation: Krzysztof M. Graczyk, Phys. Rev. C 88, 065205 (2013) https://doi.org/10.1103/PhysRevC.88.065205

Extraction of Axial Mass and Strangeness Values from the MiniBooNE Neutral Current Elastic Cross Section Measurement

Published in Physical Review C, 2013

Results of the analysis of the MiniBooNE experiment data for the neutral current elastic neutrino scattering off the CH2 target with the NuWro Monte Carlo generator are presented. The inclusion in the analysis of the two-body current contribution leads to the axial mass value MA=1.10+0.13−0.15 GeV, consistent with the older evaluations based on the neutrino-deuteron scattering data. The strange quark contribution to the nucleon spin is estimated with the value gsA=−0.4+0.5−0.3.

Recommended citation: Tomasz Golan, Krzysztof M. Graczyk, Cezary Juszczak, Jan. T. Sobczyk, Phys.Rev.C 88, 024612 (2013) https://doi.org/10.1103/PhysRevC.88.024612

N-delta weak transition

Published in Proceedings, 7th International Workshop on Neutrino-nucleus interactions in the few GeV region (NUINT 11) : Dehradun, India, March 7-11, 2011

A short review of the Rein-Sehgal and isobar models is presented. The attention is focused on the nucleon-(1232) weak transition form-factors. The results of the recent re-analyses of the ANL and BNL bubble chamber neutrino-deuteron scattering data are discussed.

Recommended citation: Krzysztof M. Graczyk, AIP Conf.Proc. 1405, 1, 134, (2011) https://doi.org/10.1063/1.3661573

Two-Photon Exchange Effect Studied with Neural Networks

Published in Physical Review C, 2011

An approach to the extraction of the two-photon exchange (TPE) correction from elastic epepep scattering data is presented. The cross section, polarization transfer (PT), and charge asymmetry data are considered. It is assumed that the TPE correction to the PT data is negligible. The form factors and TPE correcting term are given by one multidimensional function approximated by the feed forward neural network (NN). To find a model-independent approximation the Bayesian framework for the NNs is adapted. A large number of different parametrizations is considered. The most optimal model is indicated by the Bayesian algorithm. The obtained fit of the TPE correction behaves linearly in epsilon but it has a nontrivial Q2 dependence. A strong dependence of the TPE fit on the choice of parametrization is observed.

Recommended citation: Krzysztof M. Graczyk, Phys. Rev. C 84, 034314 (2011) https://doi.org/10.1103/PhysRevC.84.034314

Neural Network Parameterizations of Electromagnetic Nucleon Form Factors

Published in Journal of High Energy Physics, 2010

The electromagnetic nucleon form-factors data are studied with artificial feed forward neural networks. As a result the unbiased model-independent form-factor parametrizations are evaluated together with uncertainties. The Bayesian approach for the neural networks is adapted for chi2 error-like function and applied to the data analysis. The sequence of the feed forward neural networks with one hidden layer of units is considered. The given neural network represents a particular form-factor parametrization. The so-called evidence (the measure of how much the data favor given statistical model) is computed with the Bayesian framework and it is used to determine the best form factor parametrization.

Recommended citation: Krzysztof M. Graczyk, Piotr Płoński, Robert Sulej, JHEP 09, 053 (2010) https://doi.org/10.1007/JHEP09(2010)053

Quark-hadron duality in lepton scattering off nucleons

Published in Proceedings, 11th International Workshop on Neutrino Factories, Superbeams and Betabeams (NuFact09) : Chicago, Illinois, July 20-25,2009, 2010

Quark‐hadron (QH) duality in lepton scattering off nucleons is studied with the resonance quark model. It is shown that in the case of neutrino scattering off an isoscalar target the duality is simultaneously observed for charged and neutral currents xFνN1, FνN2, and xFνN3 weak structure functions. We demonstrate that the QH duality can be a useful property for modeling structure functions in the so‐called resonance region. As an example it is shown that combining relativistic quark model predictions with duality arguments allows a construction of the inclusive resonance Fep2 structure function.

Recommended citation: Krzysztof M. Graczyk, AIP Conf.Proc. 1222, 1, 238 (2010) https://doi.org/10.1063/1.3399304

C5A axial form factor from bubble chamber experiments

Published in Physical Review D, 2009

A careful reanalysis of both Argonne National Laboratory and Brookhaven National Laboratory data for weak single pion production is done. We consider deuteron nuclear effects and normalization (flux) uncertainties in both experiments. We demonstrate that these two sets of data are in good agreement. For the dipole parametrization of CA5(Q2), we obtain CA5(0)=1.19±0.08, MA=0.94±0.03  GeV. As an application we present the discussion of the uncertainty of the neutral current 1π0 production cross section, important for the T2K neutrino oscillation experiment.

Recommended citation: K. M. Graczyk, D. Kiełczewska, P. Przewłocki, and J. T. Sobczyk, Phys.Rev.D 80, 093001 (2009) https://doi.org/10.1103/PhysRevD.80.093001

Electromagnetic form factors of the nucleon: New fit and analysis of uncertainties

Published in Physical Review C, 2009

Electromagnetic form factors of proton and neutron, obtained from a new fit of data, are presented. The proton form factors are obtained from a simultaneous fit to the ratio μpGEp/GMp determined from polarization transfer measurements and to ep elastic cross section data. Phenomenological two-photon exchange corrections are taken into account. The present fit for protons was performed in the kinematical region Q2∈(0,6) GeV2. For both protons and neutrons we use the latest available data. For all form factors, the uncertainties and correlations of form factor parameters are investigated with the χ2 method.

Recommended citation: W. M. Alberico, S. M. Bilenky, C. Giunti, and K. M. Graczyk, Phys. Rev. C 79, 065204 (2009) https://doi.org/10.1103/PhysRevC.79.065204

The ratio of e+- p scattering cross sections predicted from the global fit of elastic ep data

Published in Joural of Physics G, 2009

We present predictions for the value of the cross section ratio σ(e+p → e+p)/σ(e−p → e−p), determined from our fit of the elastic ep cross section and polarization data. In this fit, we took into account the phenomenological two-photon exchange dispersive correction. The cross section ratios which are expected to be measured by the VEPP-3 experiment are computed. The kinematical region which will be covered by the E04-116 JLab experiment is also considered. It is shown that for both experiments the predicted cross section ratios deviate from unity by more than 3σ.

Recommended citation: W. M. Alberico, S. M. Bilenky, C Giunti, and K. M. Graczyk, J. Phys. G: Nucl. Part. Phys. 36 115009 (2009) https://doi.org/10.1088/0954-3899/36/11/115009

C5A form factor from ANL experiment

Published in Acta Physica Polonica B, Part of Proceedings of 45th Karpacz Winter School in Theoretical Physics: Neutrino interactions: from theory to Monte Carlo simulations. Ladek-Zdroj, Poland, February 2-11, 2009,, 2009

C5A(Q2) axial form factor is extracted from the ANL neutrino–deuteron scattering data with deuteron structure effects taken into consideration. The best fit of the CA5(Q2) axial form factor is obtained assuming dipole parametrization with C5A(0)=1.13±0.15 and MA=0.94±0.08 GeV.

Recommended citation: K. M. Graczyk, D. Kiełczewska, J. T. Sobczyk, Acta Phys. Pol. B 40, 2565 (2009) https://www.actaphys.uj.edu.pl/R/40/9/2565

Single pion production induced by neutrino-nucleon interactions

Published in Proceedings, Europhysics Conference on High energy physics (EPS-HEP 2009) : Cracow, Poland, July 16-22, 2009, 2009

This talk presents some of the results of the re-analysis of [Graczyk et al.] of the bubble chamber data for single pion production induced by neutrino scattering off deuteron. It is shown that ANL and BNL data are statistically consistent. The validity of the Adler relations (between P33(1232) resonance axial form factors) is also investigated.

Recommended citation: K. Graczyk, PoS EPS-HEP2009, 286 (2009). https://doi.org/10.22323/1.084.0286

Resonance contribution to single pion production in neutrino-nucleon scattering

Published in Proceedings Contribution to 27th International Workshop on Nuclear Theory (IWNT 2008), 23-28 June 2008. Rila Mountains, Bulgaria, 2008

Single pion production in neutrino-nucleon scattering is discussed. The neutrino energies characteristic for T2K project are considered. Two new parameterizations of C_5^A axial form factor are proposed. Both of them are obtained in simultaneous fit to ANL and BNL data. One of them (which fits better to BNL data) leads to d\sigma/dQ^2 differential cross section which is significantly reduced at low Q^2.

Recommended citation: Krzysztof M. Graczyk, arXiv:0810.1247 https://arxiv.org/abs/0810.1247

Lepton mass effects in weak charged current single pion production

Published in Physical Review D, 2008

Different approaches to take into account nonzero lepton mass effects in the Rein-Sehgal model are compared. Modification of the axial current due to a pion pole term is included, and it is shown that it leads to large reduction of the antineutrino cross section and a change of the shape of dσ/dQ2.

Recommended citation: Krzysztof M. Graczyk and Jan T. Sobczyk, Phys. Rev. D 77, 053003 (2008) https://journals.aps.org/prd/abstract/10.1103/PhysRevD.77.053003

Form factors in the quark resonance model

Published in Physical Review D, 2008

Vector and axial form factors in the quark resonance model are analyzed with a combination of theoretical and phenomenological arguments. The new form of form factors is deduced from Δ(1232) excitation models and available data. The vector part is shown to agree with the resonant contribution to electron-proton inclusive F2 data. The axial part is obtained by finding a simultaneous fit to ANL and BNL dσ/dQ2 neutrino scattering data. The best fit corresponds to CA5(0)=0.88 in the Rarita-Schwinger formalism.

Recommended citation: Krzysztof M. Graczyk and Jan T. Sobczyk, Phys. Rev. D 77, 053001 (2008) https://journals.aps.org/prd/abstract/10.1103/PhysRevD.77.053001

On description of Δ(1232) region in the Rein‐Sehgal model

Published in Proceedings, 5th International Workshop on Neutrino-Nucleus Interactions in the Few GeV Region (NUINT 07) : Batavia, USA, May 30-June 3, 2007, 2007

New vector and axial form factors in the Rein‐Sehgal model are proposed. The vector part is constructed after experimental fits of the helicity amplitudes for electroproduction of Δ(1232) resonance. The axial part is calculated after 𝑄2 distribution of events in the ANL experiment.

Recommended citation: K. Graczyk, AIP Conference Proceedings 967, 205 (2007). https://doi.org/10.1063/1.2834479

Quark-hadron duality in the Rein-Sehgal model

Published in Nuclear Physics A, 2007

The quark-hadron duality in CC and NC neutrino interactions is discussed under assumptions that single pion production is described accurately by the Rein-Sehgal model and that it allows reconstruction of the inclusive cross section in the resonance region. The duality is measured by means of integrals of structure functions in the Nachtmann variable for Q2<3Q^2<3Q2<3 GeV2^22. The results depend on the precision with which contributions from single pion production channels in the overall cross sections are known. Several approaches to evaluate them are compared. The duality is predicted to be seen for proton target reactions and to be absent for neutron and isoscalar targets. Two-component duality between resonant and valence quark contributions to structure functions is also investigated.

Recommended citation: Krzysztof M. Graczyk and Jan T. Sobczyk, Nucl.Phys.A 781, 227 (2007) https://doi.org/10.1016/j.nuclphysa.2006.10.036

Appearance of quark-hadron duality in the Rein-Sehgal model

Published in Nuclear Physics B - Proceedings Supplements, Part of Proceedings, 4th International Workshop on Neutrino nucleus interactions in the few GeV region (NUINT 05) : Okayama, Japan, September 26-29, 2005, 2006

Quark-hadron duality in neutrino-nucleon reactions is investigated under the assumption that cross sections in the resonance region are given by the Rein-Sehgal model. The quantitative analysis of the duality is done by means of appropriate integrals of the structure functions in the Nachtmann variable. We conclude that with the definition of the resonance region W∈(M+mπ,2W\in (M+m_{\pi}, 2W∈(M+mπ​,2 GeV) the duality holds for neutrino-proton reaction F2F_2F2​ structure function for Q2∈(0.5,3)Q^2\in (0.5, 3)Q2∈(0.5,3) GeV2^22 and it is absent for neutrino-neutron reaction.

Recommended citation: Krzysztof M. Graczyk, Cezary Juszczak, Jan T. Sobczyk, Nucl.Phys.B Proc.Suppl. 159, 241 (2006) https://doi.org/10.1016/j.nuclphysbps.2006.08.043

Analysis of the Rein-Sehgal Model in the Context of the Quark-Hadron Duality

Published in Part of Nuclear effects in neutrino interactions. Proceedings, 20th Max Born Symposium, Wroclaw, Poland, December 7-10, 2005, 2006

An analysis of the Rein-Sehgal model in the context of the quark–hadron duality hypothesis is presented. The resonance region structure functions reconstructed from the Rein–Sehgal model at different values of QRES2Q^2{\rm RES}QRES2​ are compared with the DIS structure functions calculated at higher QDIS2Q^2{\rm DIS}QDIS2​. The ratios of corresponding integrals in the Nachtman variable are also calculated and presented as functions of QRES2Q^{2}{\rm RES}QRES2​. The obtained functions are approximately flat for QRES2>0.5Q^2{\rm RES}>0.5QRES2​>0.5\,GeV2^22 but the quark–hadron duality is not observed.

Recommended citation: Krzysztof M. Graczyk, Acta Phys.Polon.B 37, 2321 (2006) https://www.actaphys.uj.edu.pl/index_n.php?I=R&V=37&N=8#2321

WroNG - Wroclaw Neutrino Generator of events for single pion production

Published in Nuclear Physics B - Proceedings Supplements, Part of Proceedings, 3rd International Workshop on Neutrino-nucleus interactions in the few GeV region (NUINT 04) : Assergi, Italy, March 17-21, 2004, 2005

We constructed a new Monte Carlo generator of events for neutrino CC single pion production on free nucleon targets. The code uses dynamical models of the DIS with the PDFs modified according to the recent JLab data and of the Delta excitation. A comparison with experimental data was done in three channels for the total cross sections and for the distributions of events in invariant hadronic mass.

Recommended citation: Jan T. Sobczyk, Jarosław A. Nowak, Krzysztof M. Graczyk, Nucl.Phys.B Proc.Suppl. 139, 266 (2005) https://doi.org/10.1016/j.nuclphysbps.2004.11.218

Tau polarization in charge current neutrino-nucleon Deep Inelastic Scattering

Published in Nuclear Physics B - Proceedings Supplements, Part of Proceedings, 3rd International Workshop on Neutrino-nucleus interactions in the few GeV region (NUINT 04) : Assergi, Italy, March 17-21, 2004, 2005

Numerical results for the degree of polarization of tau- produced in (CC) neutrino-nucleon Deep Inelastic Scattering (DIS) are presented. Calculations are done in the threshold region, where the tau- scattered by the small angles and can be partially polarized. The cross sections and polarization are calculated by using the GRV98 parton distributions functions (PDFs) and the GRV98 with modifications of A. Bodek at.al. Nucl. Phys. B Proc.(Suppl) 112 (2002) 70.

Recommended citation: Krzysztof M. Graczyk, Nucl.Phys.B Proc.Suppl. 139,150 (2005) https://doi.org/10.1016/j.nuclphysbps.2004.11.230

Tau polarization in quasielastic charged-current neutrino(antineutrino)–nucleus scattering

Published in Nuclear Physics A, 2005

The quasielastic charged-current (CC) tau neutrino(antineutrino)–nucleus scattering is considered. The dependence of tau polarization on nuclear-structure effects is discussed in detail. The description of the nucleus is based on the mean-field theory (MFT). The ground state of nucleus is described using the relativistic Fermi gas model (FG). The effective mass is introduced as well as the ring random phase approximation (RPA) effects are taken into account in the framework of relativistic meson–nucleon model. The local density approximation (LDA) is used for the argon nucleus, having in mind possible application to the ICARUS experiment. The discussion concentrates on the threshold region where the can be unpolarized and the nuclear effects play an important role.

Recommended citation: Krzysztof M. Graczyk, Nucl.Phys.A 748, 313 (2005) https://doi.org/10.1016/j.nuclphysa.2004.10.029

Local density and the RPA corrections in charge current quasielastic neutrino on oxygen, argon and iron scattering

Published in arxiv, 2004

Numerical computations of cross sections for quasielastic charge current scattering of neutrino on Oxygen, Argon and Iron in Local Density Approximation (LDA) are presented. We consider processes for a few GeV neutrino energy. We include corrections from nucleon re-interaction in nucleus described by relativistic Random Phase Approximation (RPA). We adopt the relativistic Fermi gas model of nucleus with and without taking into account the effective mass of nucleons.

Recommended citation: Krzysztof M. Graczyk, nucl-th/0401053 https://arxiv.org/abs/2108.10304

The Algebraic solution of RPA equations for the charged current quasielastic neutrino nucleus scattering

Published in The European Physical Journal C, 2003

The algebraic solution of RPA equations nucleon re-interactions in the case of quasi elastic charged current neutrino - nucleus scattering is presented. Abelian algebra of matrices allows to extract four independent corrections to cross section separatly.Results of numerical computations are shown.

Recommended citation: Krzysztof M. Graczyk, Eur.Phys.J.C 31, 177 (2003) https://doi.org/10.1140/epjc/s2003-01338-6

Observation of long ionizing tracks with the ICARUS T600 first half-modul

Published in Nuclear Instruments and Methods in Physics , 2003

Recommended citation: F. Arneodo et al., Nucl.Instrum.Meth.A 508, 287 (2003) https://doi.org/10.1016/S0168-9002(03)01508-0