T2K presents hint of CP violation by neutrinos

The international T2K Collaboration strengthened its previous hint that the symmetry between matter and antimatter may be violated for neutrino oscillation.

T2K experiment in Japan

A preliminary analysis of T2K’s latest data rejects the hypothesis that neutrinos and antineutrinos oscillate with the same probability at 95% confidence (2σ) level. With nearly twice the neutrino data in 2017 compared to their 2016 results, T2K has performed a new analysis of neutrino and antineutrino data using a new event reconstruction algorithm for interactions in the far detector, Super-Kamiokande.

Today’s announcement was made by Prof Mark Hartz, of the University of Tokyo Kavli Institute for the Physics and Mathematics of the Universe (Japan) and TRIUMF (Canada), who presented the results at a colloquium at the High Energy Accelerator Research Organization (KEK) in Tsukuba, Japan. The Swiss groups of the Universities of Bern (group of Prof. A. Ereditato) and Geneva (group of Prof. A. Blondel), and of ETH Zürich (group of Prof. A. Rubbia), have made essential contributions to achieve this result.

official announcement

T2K experiment page

Neutrino signal at T2K
Neutrino signal at T2KImage: T2K experiment, Japan


  • Nuclear Physics