Probing Majorana neutrinos with double-\(\beta\) decay

• Published in: arXiv.org 2019-09
• Main Authors: collaboration, GERDA, Agostini, M, Bakalyarov, A M, Balata, M, Barabanov, I, Bauer, C, Belogurov, S, Bettini, A, Bezrukov, L, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, Comellato, T, D'Andrea, V, Demidova, E V, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fomina, M, Garfagnini, A, Giordano, M, Grabmayr, P, Gurentsov, V, Gusev, K, Hakenmüller, J, Hegai, A, Heisel, M, Hemmer, S, Hiller, R, Hult, M, Inzhechik, L V, Csáthy, J Janicskó, Jochum, J, Junker, M, Kazalov, V, Kermaïdic, Y, Kihm, T, Kirpichnikov, I V, Kirsch, A, Kish, A, Kneißl, R, Knöpfle, K T, Kochetov, O, Kornoukhov, V N, Krause, P, Kuzminov, V V, Laubenstein, M, Lazzaro, A, Lindner, M, Lippi, I, Lubsandorzhiev, B, Lutter, G, Macolino, C, Maneschg, W, Miloradovic, M, Mingazheva, R, Moseev, P, Panas, K, Pandola, L, Pelczar, K, Pertoldi, L, Piseri, P, Pullia, A, Ransom, C, Riboldi, S, Sada, C, Sala, E, Salamida, F, Schmitt, C, Schneider, B, A -K Schütz, Schulz, O, Schwingenheuer, B, Schwarz, M, Selivanenko, O, Shevchik, E, Shirchenko, M, Simgen, H, Stanco, L, Stukov, D, Vanhoefer, L, Vasenko, A A, Veresnikova, A, K von Sturm, Wagner, V, Wester, T, Wiesinger, C, Wojcik, M, Yanovich, E, Zhitnikov, I, Zhukov, S V, Zinatulina, D, Zschocke, A, Zsigmond, A J, Zuber, K, Zuzel, G
• Format: Article
• Language: English
• Subjects: Antimatter; Antiparticles; Argon; Beta decay; Beta rays; Cosmology; Fermions; Germanium; Neutrinos; Particle physics; Searching; Sensitivity
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1909.02726

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-\(\beta\) (\(0\nu\beta\beta\)) decay, a matter-creating process without the balancing emission of antimatter. So far, 0\(\nu\beta\beta\) decay has eluded detection. The GERDA collaboration searches for the \(0\nu\beta\beta\) 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\(_{1/2}\) > 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 \(0{\nu}\beta\beta\) 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 \(\beta\) decay of 0.15 - 0.44 eV, and to the cosmological relevant sum of neutrino masses of 0.46 - 1.3 eV.