Research Report
ICRR Inter-University Research Program 2020
Research Subject:
Constraining systematics at T2K and SuperKamiokande oscillation analyses using
neutrino-nucleus interaction models
Principal Investigator:
Juan Antonio Caballero Carretero (University of Seville)
Participating Researchers:​ 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)​ Guillermo D. Megias (University of Tokyo, ICRR)

Summary of Research Result：- Due to the Covid-19 pandemic, the research could not be conducted as initiallyplanned.
- ICRR Inter-University Research Program's Committee has approved the request tocarry over the research budget for the fiscal year 2021.
- We will also continue this project on FY2021 under the ICRR Inter-University Research
Program 2021.
In spite of the current situation and travel limitations, the outcomes of these projects
have been presented at:​ T2K Collaboration meetings: - Link to G. D. Megias’ talk at T2K NIWG March
2020 online collaboration pre-meeting. - Link to G. D. Megias’ talk at T2K July
2020 General Cross Section Workshop.
​ IPMU-ICRR joint seminars: - Link to G. D. Megias’ talk at IPMU-ICRR JointSeminar.
​ Neutrino 2020 International Conference: - Link to G. D. Megias’ poster atNeutrino 2020 Conference.
​ NUSTEC 2021 International Conference: - Link to J. Gonzalez-Rosa’s talk at
NUSTEC 2021 Workshop.
In connection with this project, progresses on the development and optimization ofneutrino interaction models (SuSAv2-MEC and RMF models) for the analysis ofsemi-inclusive and STV measurements of interest for T2K and SK has been also
recently published:· Constraints in modeling the quasielastic response in inclusive lepton-nucleus
scattering. R. González-Jiménez, M.B. Barbaro, J.A. Caballero, T.W. Donnelly, N.
Jachowicz, G.D. Megias, K. Niewczas, A. Nikolakopoulos, J.M. Udías. Phys. Rev. C
101, 015503 (2020). DOI link,· Semi-inclusive charged-current neutrino-nucleus cross sections in the rela-tivistic
plane wave impulse approximation. J.M. Franco-Patino, J. Gonzalez-Rosa, J.A.
Caballero, M.B. Barbaro. Phys. Rev. C 102, 064626 (2020) DOI link

· Neutrino energy reconstruction from semi-inclusive samples. R. González-Jiménez,M. B. Barbaro, J. A. Caballero, T. W. Donnelly, N. Jachowicz, G. D. Megias, K.
Niewczas, A. Nikolakopoulos, J. W. Van Orden, J. M. Udías. arXiv:2104.01701 [nucl-th](2021).
· Theoretical description of semi-inclusiveneutrino-nucleus data in the relativistic plane
wave impulse approximation. J. M. Franco-Patino, M. B. Barbaro, J. A. Caballero, G. D.
Megias. Manuscript in preparation (2021).
Work is in progress with Prof. Hayato-san (ICRR) on a joint analysis of low-energy
nuclear effects at T2K, Ninja and SK kinematics in comparison with SuSAv2-MEC andRMF models. Also, in collaboration with Hayato-san and other T2K and SK researchers,
a first implementation of the inclusive and semi-inclusive RMF-1p1h models in NEUT isexpected in the next months. This will allow the reweight of several parameters for theoscillation analysis, the study of nuclear-medium effects, and a comparison between
nuclear optical potentials and cascade models in generators, among other issues. The
outcomes of this research will be published in coming months.
With regard to the ICRR Research Program, the Univesity of Seville group (J. A.
Caballero, G. D. Megias and others) has recently applied for a 3-year R&D project of
the Spanish Ministry of Science in which Prof. Hayato-san (ICRR) has been included ascollaborator. The University of Seville consider this collaboration a research line ofstrategic interest and has recently approved a special allocation to support theparticipation of their researchers in T2K. Thus, a formal proposal of the University of
Seville to officially join the T2K Collaboration will be submitted shortly.
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