Neutrino Masses

TL;DR

This paper reviews experimental efforts to determine the absolute neutrino mass scale, highlighting methods like neutrinoless double beta decay and direct beta decay searches, crucial for understanding fundamental physics and cosmology.

Contribution

It provides an overview of current and upcoming experiments targeting neutrino mass measurement techniques and their significance in particle physics and cosmology.

Findings

Multiple experiments aim for ~100 meV sensitivity.

Neutrinoless double beta decay probes Majorana nature.

Direct beta decay searches complement cosmological constraints.

Abstract

The various experiments on neutrino oscillation evidenced that neutrinos have indeed non-zero masses but cannot tell us the absolute neutrino mass scale. This scale of neutrino masses is very important for understanding the evolution and the structure formation of the universe as well as for nuclear and particle physics beyond the present Standard Model. Complementary to deducing constraints on the sum of all neutrino masses from cosmological observations two different methods to determine the neutrino mass scale in the laboratory are pursued: the search for neutrinoless double $\beta$-decay and the direct neutrino mass search by investigating single $\beta$-decays or electron captures. The former method is not only sensitive to neutrino masses but also probes the Majorana character of neutrinos and thus lepton number violation with high sensitivity. Currently quite a few experiments with different techniques are being constructed, commissioned or are even running, which aim for a sensitivity on the neutrino mass of {\cal O}(100) meV. The principle methods and these experiments will be discussed in this short review.