Double-weak decays of and in the XENON1T and XENONnT experiments

Aprile, E.; Abe, K.; Agostini, F.; Ahmed Maouloud, S.; Alfonsi, M.; Althueser, L.; Andrieu, B.; Angelino, E.; Angevaare, J. R.; Antochi, V. C.; Martin, D. Ant??n.; Arneodo, F.; Baudis, L.; Baxter, A. L.; Bellagamba, L.; Biondi, R.; Bismark, A.; Brown, A.; Bruenner, S.; Bruno, G.; Budnik, R.; Cai, C.; Capelli, C.; Cardoso, J. M. R.; Cichon, D.; Clark, M.; Colijn, A. P.; Conrad, J.; Cuenca-Garc??a, J. J.; Cussonneau, J. P.; D'Andrea, V.; Decowski, M. P.; Di Gangi, P.; Di Pede, S.; Di Giovanni, A.; Di Stefano, R.; Diglio, S.; Eitel, K.; Elykov, A.; Farrell, S.; Ferella, A. D.; Fischer, H.; Fulgione, W.; Gaemers, P.; Gaior, R.; Gallo Rosso, A.; Galloway, M.; Gao, F.; Glade-Beucke, R.; Grandi, L.; Grigat, J.; Guida, M.; Higuera, A.; Hils, C.; Hoetzsch, L.; Howlett, J.; Iacovacci, M.; Itow, Y.; Jakob, J.; Joerg, F.; Joy, A.; Kato, N.; Kara, M.; Kavrigin, P.; Kazama, S.; Kobayashi, M.; Koltman, G.; Kopec, A.; Landsman, H.; Lang, R. F.; Levinson, L.; Li, I.; Li, S.; Liang, S.; Lindemann, S.; Lindner, M.; Liu, K.; Loizeau, J.; Lombardi, F.; Long, J.; Lopes, J. A. M.; Ma, Y.; Macolino, C.; Mahlstedt, J.; Mancuso, A.; Manenti, L.; Manfredini, A.; Marignetti, F.; Undagoitia, T. Marrod??n.; Martens, K.; Masbou, J.; Masson, D.; Masson, E.; Mastroianni, S.; Messina, M.; Miuchi, K.; Mizukoshi, K.; Molinario, A.; Moriyama, S.; Mor??, K.; Mosbacher, Y.; Murra, M.; M??ller, J.; Ni, K.; Oberlack, U.; Paetsch, B.; Palacio, J.; Peres, R.; Pienaar, J.; Pierre, M.; Pizzella, V.; Plante, G.; Qi, J.; Qin, J.; Ram??rez Garc??a, D.; Reichard, S.; Rocchetti, A.; Rupp, N.; Sanchez, L.; dos Santos, J. M. F.; Sarnoff, I.; Sartorelli, G.; Schreiner, J.; Schulte, D.; Schulte, P.; Schulze Ei??ing, H.; Schumann, M.; Scotto Lavina, L.; Selvi, M.; Semeria, F.; Shagin, P.; Shi, S.; Shockley, E.; Silva, M.; Simgen, H.; Takeda, A.; Tan, P. -L.; Terliuk, A.; Thers, D.; Toschi, F.; Trinchero, G.; Tunnell, C.; T??nnies, F.; Valerius, K.; Volta, G.; Wei, Y.; Weinheimer, C.; Weiss, M.; Wenz, D.; Wittweg, C.; Wolf, T.; Xu, Z.; Yamashita, M.; Yang, L.; Ye, J.; Yuan, L.; Zavattini, G.; Zerbo, S.; Zhong, M.; Zhu, T.

doi:10.1103/physrevc.106.024328

We present results on the search for two-neutrino double-lectron capture (2νECEC) of 124 Xe and neutrinoless double-β decay (0νββ) of 136 Xe in XENON1T. We consider captures from the K shell up to the N shell in 2νECEC = (1.1 ± 0.2stat ± 0.1sys ) × 1022 yr with a the 2νECEC signal model and measure a total half-life of T1/2 0.87 kg yr isotope exposure. The statistical significance of the signal is 7.0σ . We use XENON1T data with 36.16 kg yr of 136 Xe exposure to search for 0νββ. We find no evidence of a signal and set a lower limit on 0νββ > 1.2 × 1024 yr at 90% CL. This is the best result from a dark matter detector without the half-life of T1/2 an enriched target to date. We also report projections on the sensitivity of XENONnT to 0νββ. Assuming a 0νββ > 2.1 × 1025 yr at 90% CL, corresponding to an 275 kg yr 136 Xe exposure, the expected sensitivity is T1/22 effective Majorana mass range of mββ < (0.19–0.59) eV/c .