Joint Neutrino Oscillation Analysis From the T2K and NOvA Experiments

Author(s)

• S. Abubakar
• M. A. Acero
• B. Acharya
• P. Adamson
• N. Anfimov
• A. Antoshkin
• E. Arrieta-Diaz
• L. Asquith
• A. Aurisano
• D. Azevedo
• A. Back
• N. Balashov
• P. Baldi
• A. Bambah
• E. F. Barenboim
• A. Bashyal
• A. Basti
• K. Bromberg
• N. Buchanan
• Roberto Petti, University of South CarolinaFollow

Document Type

Article

Abstract

The landmark discovery that neutrinos have mass and can change type (or flavour) as they propagate—a process called neutrino oscillation^1,2,3,4,5,6—has opened up a rich array of theoretical and experimental questions being actively pursued today. Neutrino oscillation remains the most powerful experimental tool for addressing many of these questions, including whether neutrinos violate charge-parity (CP) symmetry, which has possible connections to the unexplained preponderance of matter over antimatter in the Universe^7,8,9,10,11. Oscillation measurements also probe the mass-squared differences between the different neutrino mass states (Δm²), whether there are two light states and a heavier one (normal ordering) or vice versa (inverted ordering), and the structure of neutrino mass and flavour mixing¹². Here we carry out the first joint analysis of datasets from NOvA¹³ and T2K¹⁴, the two currently operating long-baseline neutrino oscillation experiments (hundreds of kilometres of neutrino travel distance), taking advantage of our complementary experimental designs and setting new constraints on several neutrino sector parameters. This analysis provides new precision on the Δm²₃₂ mass difference, finding 2.43^+0.04_−0.03 × 10⁻³ eV² in the normal ordering and −2.48^+0.03_−0.04 × 10⁻³ eV² in the inverted ordering, as well as a 3σ interval on δ_CP of [−1.38π, 0.30π] in the normal ordering and [−0.92π, −0.04π] in the inverted ordering. The data show no strong preference for either mass ordering, but notably, if inverted ordering were assumed true within the three-flavour mixing model, then our results would provide evidence of CP symmetry violation in the lepton sector.

Digital Object Identifier (DOI)

https://doi.org/10.1038/s41586-025-09599-3

Publication Info

Published in Nature, Volume 646, 2025, pages 818-824.

Rights

©The Author(s) 2025  This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

APA Citation

Abubakar, S., Acero, M. A., Acharya, B., Adamson, P., N. Anfimov, A. Antoshkin, E. Arrieta-Diaz, Asquith, L., A. Aurisano, Azevedo, D., Back, A., N. Balashov, Baldi, P., Bambah, B. A., Bannister, E. F., Barros, A., A. Bat, Bays, K., Bernstein, R., & Bezerra, C. (2025). Joint neutrino oscillation analysis from the T2K and NOvA experiments. Nature, 646, 818–824.https://doi.org/10.1038/s41586-025-09599-3