EMMI-GSI-Colloquium:"Neutrinoless double beta decay: the quest for Majorana neutrinos"

Neutrinoless double beta decay is a process that violates lepton number conservation. This decay is predicted if neutrinos are Majorana particles, ie. identical to their antiparticles, which is considered as one of the most fundamental questions in particle physics. Also other extensions of the Standard Model of particle physics could generate neutrinoless double beta decay. After a general introduction and a short overview of the experimental challenges and present projects, I focus on the results from Phase I and the plans for Phase II of the GERmanium Detector Array (GERDA) experiment at the Gran Sasso Laboratory (Italy) searching for neutrinoless double beta decay of the isotope 76Ge.