Search for neutrinoless double-beta decay
After the pioneering work of the Heidelberg-Moscow (HDM) and International Germanium Experiment (IGEX) groups, the second round of neutrinoless double-β decay searches currently underway has or will im- prove the life-time limits of double-β decay candidates by a factor of two to three, reaching in the near future the T1=2 = 3 × 1025 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 1025 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 ∼ 2 × 1026 yr or ∼ 50 meV.