Status of direct neutrino mass measurements

Abstract

The absolute neutrino mass scale is one of the big open questions in particle physics, astrophysics and cosmology. Cosmological observations and neutrinoless double beta decay experiments provide an indirect access to the absolute neutrino mass scale, but are model-dependent. A model independent, direct approach to determine the neutrino mass is the precise investigation of weak decays. The KATRIN experiment, which is currently under construction, will improve the neutrino mass sensitivity to 200 meV/c2 via the precise measurement of the tritium β -decay spectrum close to the endpoint energy with a high-resolution electrostatic spectrometer. Experiments using alternative approaches such as spectroscopy via coherent cyclotron radiation or calorimetric measurements of 163Ho electron capture are being developed. This article briefly reviews the current status of different direct neutrino mass measurement experiments.