2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/179048The present experimental status in the search for neutrinoless double beta decay is reviewed, with emphasis on the first indication for neutrinoless double beta decay found in the Heidelberg-Moscow experiment, giving first evidence for lepton number violation and a Majorana nature of the neutrinos. Future perspectives of the field are briefly outlined.37 pages, latex, 23 figures, Published in Found. Phys. 32 (2002) 1181-1223 and Presented at Fourth Heidelberg International Conference on Dark Matter in Astro- and Particle Physics, DARK2002, Cape Town, South Africa, 4 - 9 February, 2002, eds. H.V. Klapdor-Kleingrothaus and R. Viollier, Springer-Verlag Heidelberg, (2002) 367-403 see Home Page of Heidelberg Non-Accelerator Particle Physics Group: http://www.mpi-hd.mpg.de/non_acc/buecher.html#DARK2002High Energy Physics - Phenomenologytext