[Research Press Release] Particle physics: Teamwork enhances understanding of neutrino behaviour
23 October 2025
An improved understanding of the behaviour of neutrinos is gained by the joint analysis of datasets from two neutrino experiments: NOvA and T2K, in the US and Japan, respectively. The findings, published in Nature this week, provide further insights into a process called neutrino oscillation, which could be used to probe the matter–antimatter asymmetry in the Universe.
Neutrinos are tiny fundamental particles that have the potential to shed light on the origins of matter in the Universe, but they are difficult to study, owing to their weak interaction with matter. The particles come in different forms, or ‘flavours’, that evolve via a process called neutrino oscillation. Studying this process can uncover details of neutrino mass and how the flavours mix, including whether there is any difference, or asymmetry, between the way neutrinos or anti-neutrinos (their antimatter counterpart) oscillate. Identifying asymmetries may help to explain the origin of the current prevalence of matter over antimatter in the Universe. Neutrino oscillation experiments in recent decades have provided some insights, but many questions remain unanswered.
NOvA and T2K are two currently operating long-baseline neutrino oscillation experiments, detecting neutrinos that have travelled hundreds of kilometres through the Earth, from an accelerator complex to a large detector. The joint analysis of datasets from these experiments provides new constraints related to neutrino masses and fundamental symmetries. Both datasets have been analysed before, but the combined analyses improve the statistical significance of the results and provide a more-precise measurement of the differences in neutrino masses and the asymmetry in neutrino–antineutrino oscillations. These results reveal a precise estimate of the parameter that governs the difference in oscillations between neutrinos and antineutrinos. While asymmetry between neutrinos and antineutrinos is not directly observed, the data hint that a violation of symmetry between the two particles is possible.
Combining the analyses takes advantage of the complementary sensitivities of the two experiments and demonstrates the value of collaboration.
- Article
- Open access
- Published: 22 October 2025
The NOvA Collaboration., The T2K Collaboration. Joint neutrino oscillation analysis from the T2K and NOvA experiments. Nature 646, 818–824 (2025). https://doi.org/10.1038/s41586-025-09599-3
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