Based on one month of running, researchers on the Karlsruhe Tritium Neutrino (KATRIN) experiment in Germany have determined a first upper bound on the mass of the electron antineutrino. Presenting the results earlier today at Topics in Astroparticle and Underground Physics 2019 in Toyama, Japan, scientific co-spokesperson Guido Drexlin reported a limit of mν < 1.1 eV at 90% confidence — already improving upon the limit of 2.3 eV set by predecessor experiments. Further data should allow the collaboration to reduce the limit to 0.2 eV or discover the actual mass, if it is larger than 0.35 eV.
A public colloquium and press conference will be webcast on Monday.
More to follow.