"Rival" neutrino experiments NOvA and T2K publish first joint analysis - KEK

The T2K experiment in Japan and the NOvA experiment in the United States conducted a joint analysis and published their first results in the journal Nature. Both are long-baseline neutrino oscillation experiments using accelerators, and by leveraging their different baselines and energy conditions, they achieved precision measurements of neutrino oscillations. As a result, they succeeded in reducing the uncertainty in the differences between neutrino masses to below 2%. Although the ordering of the three neutrino masses is still unknown, their results show that depending on this ordering, the magnitude of CP symmetry violation—a difference in behavior between particles and antiparticles—would be strongly constrained. This achievement marks an important step toward uncovering CP symmetry violation in neutrinos and the origin of the matter–antimatter asymmetry in the universe. The joint analysis combined ten years of T2K data collected since 2010 and six years of NOvA data collected since 2014, and it also demonstrates the strength of collaboration between two international experiments that are competitive yet complementary.

Fig. 1 : T2K in Japan (left) and NOvA in the United States (right) are both long-baseline experiments: they each shoot an intense beam of neutrinos that passes through both a near detector close to the neutrino source and a far detector hundreds of kilometers away. Both experiments compare data recorded in each detector to learn about neutrinos’ behavior and properties.

Publication Details

Title: Joint neutrino oscillation analysis of data from the T2K and NOvA experiments
Authors: S.Abubakar et al. (NOvA and T2K collaboration)
Journal: Nature Vol. 646, pp.818-824, on October 22, 2025
https://www.nature.com/articles/s41586-025-09599-3

Please refer to the press release for details.

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