Eur. Phys. J. C (2025) 85: 1414
https://doi.org/10.1140/epjc/s10052-025-14836-0

Regular Article - Experimental Physics

Testing T2K’s Bayesian constraints with priors in alternate parameterisations

¹ Department of Theoretical Physics, University Autonoma Madrid, 28049, Madrid, Spain
² Laboratory for High Energy Physics (LHEP), University of Bern, Albert Einstein Center for Fundamental Physics, Bern, Switzerland
³ Department of Physics, Boston University, Boston, Massachusetts, USA
⁴ Department of Physics and Astronomy, University of California, Irvine, Irvine, California, USA
⁵ IRFU, CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France
⁶ Department of Physics, University of Colorado at Boulder, Boulder, Colorado, USA
⁷ Department of Physics, Colorado State University, Fort Collins, CO, USA
⁸ Department of Physics, Duke University, Durham, NC, USA
⁹ Department of Atomic Physics, Eötvös Loránd University, Budapest, Hungary
¹⁰ ETH Zurich, Institute for Particle Physics and Astrophysics, Zurich, Switzerland
¹¹ CERN European Organization for Nuclear Research, 1211, Genéve 23, Switzerland
¹² University of Geneva, Section de Physique, DPNC, Geneva, Switzerland
¹³ School of Physics and Astronomy, University of Glasgow, Glasgow, UK
¹⁴ H. Niewodniczanski Institute of Nuclear Physics PAN, Cracow, Poland
¹⁵ High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan
¹⁶ Department of Physics, University of Houston, Houston, TX, USA
¹⁷ Institut de Fisica d’Altes Energies (IFAE) - The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra (Barcelona), Spain
¹⁸ Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, 55128, Mainz, Germany
¹⁹ IFIC (CSIC & University of Valencia), Valencia, Spain
²⁰ Institute For Interdisciplinary Research in Science and Education (IFIRSE), ICISE, Quy Nhon, Vietnam
²¹ Imperial College London, Department of Physics, London, UK
²² Dipartimento Interuniversitario di Fisica, INFN Sezione di Bari and Università e Politecnico di Bari, Bari, Italy
²³ Dipartimento di Fisica, INFN Sezione di Napoli and Università di Napoli, Naples, Italy
²⁴ Dipartimento di Fisica, INFN Sezione di Padova and Universita di Padova, Padova, Italy
²⁵ INFN Sezione di Roma and Università di Roma “La Sapienza”, Rome, Italy
²⁶ Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia
²⁷ International Centre of Physics, Institute of Physics (IOP), Vietnam Academy of Science and Technology (VAST), 10 Dao Tan, Ba Dinh, Hanoi, Vietnam
²⁸ ILANCE, CNRS - University of Tokyo International Research Laboratory, Kashiwa, 277-8582, Chiba, Japan
²⁹ Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba, Japan
³⁰ Department of Physics, Keio University, Kanagawa, Japan
³¹ Department of Physics, King’s College London, Strand, WC2R 2LS, London, UK
³² Kobe University, Kobe, Japan
³³ Department of Physics, Kyoto University, Kyoto, Japan
³⁴ Physics Department, Lancaster University, Lancaster, UK
³⁵ Lawrence Berkeley National Laboratory, 94720, Berkeley, CA, USA
³⁶ Ecole Polytechnique, IN2P3-CNRS, Laboratoire Leprince-Ringuet, Palaiseau, France
³⁷ Department of Physics, University of Liverpool, Liverpool, UK
³⁸ Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LS, USA
³⁹ Joint Institute for Nuclear Research, Dubna, Moscow Region, Russia
⁴⁰ Department of Physics and Astronomy, Michigan State University, East Lansing, MI, USA
⁴¹ Department of Physics, Miyagi University of Education, Sendai, Japan
⁴² National Centre for Nuclear Research, Warsaw, Poland
⁴³ Department of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, New York, USA
⁴⁴ Department of Physics, Okayama University, Okayama, Japan
⁴⁵ Department of Physics, Osaka Metropolitan University, Osaka, Japan
⁴⁶ Department of Physics, Oxford University, Oxford, UK
⁴⁷ Department of Physics and Astronomy, University of Pennsylvania, 19104, Philadelphia, PA, USA
⁴⁸ Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
⁴⁹ School of Physics and Astronomy, Queen Mary University of London, London, UK
⁵⁰ Department of Physics, University of Regina, Regina, Saskatchewan, Canada
⁵¹ Department of Physics and Astronomy, University of Rochester, Rochester, NY, USA
⁵² Department of Physics, Royal Holloway University of London, Egham, Surrey, UK
⁵³ III. Physikalisches Institut, RWTH Aachen University, Aachen, Germany
⁵⁴ Departamento de Física Atómica, Molecular y Nuclear, Universidad de Sevilla, 41080, Sevilla, Spain
⁵⁵ Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
⁵⁶ Institute of Physics, University of Silesia, Katowice, Poland
⁵⁷ Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), Sorbonne Université, Université Paris Diderot, CNRS/IN2P3, Paris, France
⁵⁸ STFC, Rutherford Appleton Laboratory, Harwell Oxford and Daresbury Laboratory, Warrington, UK
⁵⁹ Department of Physics, University of Tokyo, Tokyo, Japan
⁶⁰ Institute for Cosmic Ray Research, Kamioka Observatory, University of Tokyo, Kamioka, Japan
⁶¹ Institute for Cosmic Ray Research, Research Center for Cosmic Neutrinos, University of Tokyo, Kashiwa, Japan
⁶² Department of Physics, Tokyo Institute of Technology, Tokyo, Japan
⁶³ Department of Physics, Tokyo Metropolitan University, Tokyo, Japan
⁶⁴ Faculty of Science and Technology, Department of Physics, Tokyo University of Science, Noda, Chiba, Japan
⁶⁵ Department of Physics, University of Toronto, Toronto, ON, Canada
⁶⁶ TRIUMF, Vancouver, British Columbia, Canada
⁶⁷ Faculty of Physics, University of Warsaw, Warsaw, Poland
⁶⁸ Institute of Radioelectronics and Multimedia Technology, Warsaw University of Technology, Warsaw, Poland
⁶⁹ Faculty of Science, Department of Physics, Tohoku University, Miyagi, Japan
⁷⁰ Department of Physics, University of Warwick, Coventry, United Kingdom
⁷¹ Department of Physics, University of Winnipeg, Winnipeg, Manitoba, Canada
⁷² Faculty of Physics and Astronomy, Wroclaw University, Wroclaw, Poland
⁷³ Department of Physics, Yokohama National University, Yokohama, Japan
⁷⁴ Department of Physics and Astronomy, York University, Toronto, Ontario, Canada
⁷⁵ Department of Physics and Astronomy, Ghent University, Proeftuinstraat 86, 9000, Gent, Belgium
⁷⁶ South Dakota School of Mines and Technology, 501 East Saint Joseph Street, 57701, Rapid City, SD, USA
⁷⁷ Department of Physics, University of Toyama, Toyama, Japan
⁷⁸ VNU University of Science, Vietnam National University, Hanoi, Vietnam
⁷⁹ School of Physics and Astronomy, University of Minnesota, Minneapolis, MI, USA
⁸⁰ SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA, USA
⁸¹ Université Paris-Saclay, Paris, France
⁸² J-PARC, Tokai, Japan
⁸³ Kavli IPMU (WPI), the University of Tokyo, Japan
⁸⁴ Moscow Institute of Physics and Technology (MIPT), Moscow region, Russia and National Research Nuclear University ”MEPhI”, Moscow, Russia
⁸⁵ IPSA-DRII, Paris, France
⁸⁶ the Graduate University of Science and Technology, Vietnam Academy of Science and Technology, Hanoi, Vietnam
⁸⁷ JINR, Dubna, Russia
⁸⁸ Nambu Yoichiro Institute of Theoretical and Experimental Physics (NITEP), Osaka, Japan
⁸⁹ BMCC/CUNY, Science Department, New York, New York, USA
⁹⁰ Departament de Fisica de la Universitat Autonoma de Barcelona, Barcelona, Spain

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Received: 8 July 2025
Accepted: 19 September 2025
Published online: 12 December 2025

Abstract

Bayesian analysis results require a choice of prior distribution. In long-baseline neutrino oscillation physics, the usual parameterisation of the mixing matrix induces a prior that privileges certain neutrino mass and flavour state symmetries. Here we study the effect of privileging alternate symmetries on the results of the T2K experiment. We find that constraints on the level of CP violation (as given by the Jarlskog invariant) are robust under the choices of prior considered in the analysis. On the other hand, the degree of octant preference for the atmospheric angle depends on which symmetry has been privileged.