Search for Neutrinoless Double-Beta Decay

TL;DR

This paper reviews recent and upcoming large-scale experiments searching for neutrinoless double-beta decay, highlighting their current limits, technological progress, and potential to explore the inverted hierarchy neutrino mass regime.

Contribution

It provides an overview of the latest experimental efforts and future prospects in neutrinoless double-beta decay searches, emphasizing the significance of KamLAND-Zen and upcoming 1-ton experiments.

Findings

GERDA, EXO-200, and KamLAND-Zen have set half-life limits exceeding 10^{25} years.

Future experiments aim to reach sensitivities around 3 x 10^{25} years.

KamLAND-Zen is close to probing the inverted hierarchy neutrino mass regime.

Abstract

After the pioneering work of the Heidelberg-Moscow (HDM) and International Germanium Experiment (IGEX) groups, the second round of neutrinoless double-$\beta$ decay searches currently underway has or will improve the life-time limits of double-$\beta$ decay candidates by a factor of two to three, reaching in the near future the $T_{1/2} = 3 \times 10^{25}$ yr level. This talk will focus on the large-scale experiments GERDA, EXO-200, and KamLAND-Zen, which have reported already lower half-life time limits in excess of $10^{25}$ yr. Special emphasis is given to KamLAND-Zen, which is expected to approach the inverted hierarchy regime before future 1-ton experiments probe completely this life-time or effective neutrino-mass regime, which starts at $\approx 2 \times 10^{26}$ yr or $\approx 50$ meV.