Neutrino mass limit from tritium beta decay

Understand

The paper reviews recent experiments on tritium beta spectroscopy searching for the absolute value of the electron neutrino mass $m(\nu_e)$.

• By use of dedicated electrostatic filters with high acceptance and resolution, the uncertainty on the observable $m^2(\nu_e)$ has been pushed down to about 3 eV$^2$.
• The new upper limit of the mass is $m(\nu_e) < 2$ eV at 95% C.L.
• In view of erroneous and unphysical mass results obtained by some earlier experiments in beta decay, particular attention is paid to systematic effects.