Probing Majorana neutrinos with double-$β$ decay
Creators: name: GERDA Collaboration
name: Agostini, M.
name: Bakalyarov, A. M.
name: Balata, M.
name: Barabanov, I.
name: Baudis, L.
name: Bauer, C.
name: Bellotti, E.
name: Belogurov, S.
name: Bettini, A.
name: Bezrukov, L.
name: Borowicz, D.
name: Brudanin, V.
name: Brugnera, R.
name: Caldwell, A.
name: Cattadori, C.
name: Chernogorov, A.
name: Comellato, T.
name: D'Andrea, V.
name: Demidova, E. V.
name: Di Marco, N.
name: Domula, A.
name: Doroshkevich, E.
name: Egorov, V.
name: Falkenstein, R.
name: Fomina, M.
name: Gangapshev, A.
name: Garfagnini, A.
name: Giordano, M.
name: Grabmayr, P.
name: Gurentsov, V.
name: Gusev, K.
name: Hakenmüller, J.
name: Hegai, A.
name: Heisel, M.
name: Hemmer, S.
name: Hiller, R.
name: Hofmann, W.
name: Hult, M.
name: Inzhechik, L. V.
name: Csáthy, J. Janicskó
name: Jochum, J.
name: Junker, M.
name: Kazalov, V.
name: Kermaïdic, Y.
name: Kihm, T.
name: Kirpichnikov, I. V.
name: Kirsch, A.
name: Kish, A.
name: Klimenko, A.
name: Kneißl, R.
name: Knöpfle, K. T.
name: Kochetov, O.
name: Kornoukhov, V. N.
name: Krause, P.
name: Kuzminov, V. V.
name: Laubenstein, M.
name: Lazzaro, A.
name: Lindner, M.
name: Lippi, I.
name: Lubashevskiy, A.
name: Lubsandorzhiev, B.
name: Lutter, G.
name: Macolino, C.
name: Majorovits, B.
name: Maneschg, W.
name: Miloradovic, M.
name: Mingazheva, R.
name: Misiaszek, M.
name: Moseev, P.
name: Nemchenok, I.
name: Panas, K.
name: Pandola, L.
name: Pelczar, K.
name: Pertoldi, L.
name: Piseri, P.
name: Pullia, A.
name: Ransom, C.
name: Riboldi, S.
name: Rumyantseva, N.
name: Sada, C.
name: Sala, E.
name: Salamida, F.
name: Schmitt, C.
name: Schneider, B.
name: Schönert, S.
name: Schütz, A. -K.
name: Schulz, O.
name: Schwingenheuer, B.
name: Schwarz, M.
name: Selivanenko, O.
name: Shevchik, E.
name: Shirchenko, M.
name: Simgen, H.
name: Smolnikov, A.
name: Stanco, L.
name: Stukov, D.
name: Vanhoefer, L.
name: Vasenko, A. A.
name: Veresnikova, A.
name: von Sturm, K.
name: Wagner, V.
name: Wegmann, A.
name: Wester, T.
name: Wiesinger, C.
name: Wojcik, M.
name: Yanovich, E.
name: Zhitnikov, I.
name: Zhukov, S. V.
name: Zinatulina, D.
name: Zschocke, A.
name: Zsigmond, A. J.
name: Zuber, K.
name: Zuzel, G.
Publisher: name: arXiv
Year: 2019
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: A discovery that neutrinos are not the usual Dirac but Majorana fermions, i.e. identical to their antiparticles, would be a manifestation of new physics with profound implications for particle physics and cosmology. Majorana neutrinos would generate neutrinoless double-$β$ ($0νββ$) decay, a matter-creating process without the balancing emission of antimatter. So far, 0$νββ$ decay has eluded detection. The GERDA collaboration searches for the $0νββ$ decay of $^{76}$Ge by operating bare germanium detectors in an active liquid argon shield. With a total exposure of 82.4 kg$\cdot$yr, we observe no signal and derive a lower half-life limit of T$_{1/2}$ &gt; 0.9$\cdot$10$^{26}$ yr (90% C.L.). Our T$_{1/2}$ sensitivity assuming no signal is 1.1$\cdot$10$^{26}$ yr. Combining the latter with those from other $0νββ$ decay searches yields a sensitivity to the effective Majorana neutrino mass of 0.07 - 0.16 eV, with corresponding sensitivities to the absolute mass scale in $β$ decay of 0.15 - 0.44 eV, and to the cosmological relevant sum of neutrino masses of 0.46 - 1.3 eV.
description: Authors' main+supplementary text: 13+28 pages, 3+12 figures, 1+7 tables. Definite version to be published in Science