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Research Result Report
ICRR Inter-University Research Program 2023
Research Subject: Constraining systematics at T2K and SuperKamiokande
oscillation analyses using neutrino-nucleus interaction models
Principal Investigator: Guillermo Daniel Megias Vazquez, University of SevilleParticipating Researchers:
Juan Antonio Caballero Carretero, University of Seville
Juan Manuel Franco Patiño, University of Seville
Jesús González Rosa, University of Seville
Raúl González Jiménez, Complutense University of Madrid
José Manuel Udías Moinelo, Complutense University of Madrid
Maria Benedetta Barbaro, University of Turin and INFN
T. William Donnelly, Massachusetts Institute of Technology (MIT)Kimihiro Okumura, University of Tokyo, ICRR
Yoshinari Hayato, University of Tokyo, ICRR
Laura Munteanu, CERN
Stephen Dolan, CERN
Summary of Research Result：
Progresses on the development and optimization of neutrino interaction models(SuSAv2-MEC and RMF models) for the analysis of data from T2K and otherexperiments have been published in FY2023 together with other T2K papers incommon with ICRR members:- Weak Neutrino (Antineutrino) Charged-Current Responses and Scaling for Nuclear
Matter in the Relativistic Mean Field. Sara Cruz-Barrios, Guillermo D. Megias, Juan
A. Caballero. Universe 2023, 9(5), 240 (2023).
- Superscaling in the resonance region for neutrino-nucleus scattering: The SuSAv2
dynamical coupled-channels model. J. Gonzalez-Rosa, G. D. Megias, J. A. Caballero,
M. B. Barbaro, J. M. Franco-Patino. Phys. Rev. D 108, 113008 (2023).
- New model comparison for semi-inclusive charged-current electron and muon
neutrino scattering by 40Ar in the energy range of the MicroBooNE experiment. J. M.
Franco-Patino, S. Dolan, R. Gonzalez-Jimenez, M. B. Barbaro, J. A. Caballero, andG. D. Megias. Phys. Rev. D 109, 013004 (2024).
- K. Abe et al. (T2K Collaboration), Measurements of neutrino oscillation parametersfrom the T2K experiment using 3.6 x 1021 protons on target. Eur. Phys. J. C 83, 782(2023).
- K. Abe et al. (T2K Collaboration), First measurement of \mu_\nu CC interactions onhydrocarbon without pions in the FS using multiple detectors with correlated energy
spectra at T2K. Phys. Rev. D 108, 112009 (2023).

Work is in progress with Prof. Hayato-san (ICRR) to include the DCC model from theOsaka group in the SuSAv2 model and subsequently implement it in the NEUT event
generator used in T2K and SuperKamiokande. This will allow to use different
approaches to analyze the resonant regime in neutrino-nucleus reactions. Also, in
collaboration with Hayato-san and other T2K members, a first implementation of theinclusive and semi-inclusive SuSAv2 and RMF-1p1h models in NEUT is also inprogress. This will allow the reweight of several parameters for the oscillation
analysis, the study of nuclear-medium effects, and a comparison between nuclearForm 8

optical potentials and cascade models in generators, among other issues. Someoutcomes of this research have been recently published and additional works areexpected to be published in coming months. They have been also presented atseveral conferences and meetings, such as:--G. D. Megias: The theory experience using experimental data, NuXtract
workshop at CERN (Geneva, Switzerland), October 2023.
G. D. Megias: Uncertainties in superscaling models: quasielastic, mesonexchange currents and inelastic regimes. Workshop: “Theoretical Physics
Uncertainties to Empower Neutrino Experiments”, Institute of Nuclear Theory,
University of Washington, Seattle (USA). October-November 2023
J. Gonzalez-Rosa: Superscaling in the inelastic region: The SuSAv2-inelastic
model. NuInt24: 14th International Workshop on Neutrino-Nucleus
Interactions. Sao Paulo (Brazil), April 2024

With regard to the ICRR Research Program, the Univ. of Seville group has a 3-year
R&D project of the Spanish Ministry of Science in which Prof. Hayato-san (ICRR)
participates as collaborator. A continuation of this project for the next 3-years has
been recently submitted to the Spanish Ministry of Science, which includes Prof.
Hayato-san and Prof. Okumura-san as collaborators. The Univ. of Seville consider allthese projects a research line of strategic interest, having approved a special
allocation to support the participation of their researchers in T2K.
We will also continue these projects on FY2024 under the ICRR Inter-University
Research Program 2024.

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