Double-weak decays of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Xe</mml:mi><mml:mprescripts/><mml:none/><mml:mn>124</mml:mn></mml:mmultiscripts></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Xe</mml:mi><mml:mprescripts/><mml:none/><mml:mn>136</mml:mn></mml:mmultiscripts></mml:math> in the XENON1T and XENONnT experiments
E. Aprile, K. Abe, F. Agostini, S. Ahmed Maouloud, M. Alfonsi, L. Althueser, B. Andrieu, E. Angelino, J. R. Angevaare, V. C. Antochi, D. Antón Martin, F. Arneodo, L. Baudis, A. Baxter, L. Bellagamba, R. Biondi, A. Bismark, A. Brown, S. Bruenner, G. Bruno, R. Budnik, Ce Cai, C. Capelli, J. M. R. Cardoso, D. Cichon, M. Clark, A. P. Colijn, J. M. Conrad, J. J. Cuenca-García, J. P. Cussonneau, V. D’Andrea, M. P. Decowski, P. Di Gangi, S. Di Pede, A. Di Giovanni, R. Di Stefano, S. Diglio, K. Eitel, A. Elykov, S. Farrell, A. D. Ferella, H. Fischer, W. Fulgione, P. Gaemers, R. Gaïor, A. Gallo Rosso, M. Galloway, F. Gao, R. Glade-Beucke, L. Grandi, J. Grigat, M. Guida, A. Higuera, C. Hils, L. Hoetzsch, J. Howlett, M. Iacovacci, Y. Itow, J. Jakob, F. Joerg, A. Joy, Natsuko Kato, M. Kara, P. Kavrigin, S. Kazama, M. Kobayashi, G. Koltman, A. Kopec, H. Landsman, R. F. Lang, L. J. Levinson, I. Li, S. Li, S. Liang, S. Lindemann, M. Lindner, K. Liu, J. Loizeau, F. Lombardi, J. Long, J. A. M. Lopes, Y. Ma, C. Macolino, J. Mahlstedt, A. Mancuso, L. Manenti, A. Manfredini, Fabrizio Marignetti, T. Marrodán Undagoitia, K. Martens, J. Masbou, D. Masson, E. Masson, S. Mastroianni, M. Messina, K. Miuchi, K. Mizukoshi, A. Molinario, S. Moriyama, K. Morå
Abstract
This work uses two liquid-xenon detectors in the Gran Sasso Underground Laboratory, originally designed to search for dark matter, to find evidence for neutrinoless double-$\ensuremath{\beta}$ decay. The results indicate that such dark-matter detectors can provide important constraints and potential discoveries beyond their original purpose and design. This is further illustrated by the first statistically significant observation of a rare two-neutrino decay of ${}^{124}$Xe.