Search for the Majorana Nature of Neutrinos in the Inverted Mass Ordering Region with KamLAND-Zen

S Abe; S Asami; M Eizuka; S Futagi; A Gando; Y Gando; T Gima; A Goto; T Hachiya; K Hata; S Hayashida; K Hosokawa; K Ichimura; S Ieki; H Ikeda; K Inoue; K Ishidoshiro; Y Kamei; N Kawada; Y Kishimoto; M Koga; M Kurasawa; N Maemura; T Mitsui; H Miyake; T Nakahata; K Nakamura; K Nakamura; R Nakamura; H Ozaki; T Sakai; H Sambonsugi; I Shimizu; J Shirai; K Shiraishi; A Suzuki; Y Suzuki; A Takeuchi; K Tamae; K Ueshima; H Watanabe; Y Yoshida; S Obara; A K Ichikawa; D Chernyak; A Kozlov; K Z Nakamura; S Yoshida; Y Takemoto; S Umehara; K Fushimi; K Kotera; Y Urano; B E Berger; B K Fujikawa; J G Learned; J Maricic; S N Axani; J Smolsky; Z Fu; L A Winslow; Y Efremenko; H J Karwowski; D M Markoff; W Tornow; S Dell'Oro; T O'Donnell; J A Detwiler; S Enomoto; M P Decowski; C Grant; A Li; H Song; KamLAND-Zen Collaboration

doi:10.1103/PhysRevLett.130.051801

Search for the Majorana Nature of Neutrinos in the Inverted Mass Ordering Region with KamLAND-Zen

Phys Rev Lett. 2023 Feb 3;130(5):051801. doi: 10.1103/PhysRevLett.130.051801.

Authors

S Abe¹, S Asami¹, M Eizuka¹, S Futagi¹, A Gando¹, Y Gando¹, T Gima¹, A Goto¹, T Hachiya¹, K Hata¹, S Hayashida¹, K Hosokawa¹, K Ichimura¹, S Ieki¹, H Ikeda¹, K Inoue^{1

2}, K Ishidoshiro¹, Y Kamei¹, N Kawada¹, Y Kishimoto^{1

2}, M Koga^{1

2}, M Kurasawa¹, N Maemura¹, T Mitsui¹, H Miyake¹, T Nakahata¹, K Nakamura¹, K Nakamura¹, R Nakamura¹, H Ozaki^{1

3}, T Sakai¹, H Sambonsugi¹, I Shimizu¹, J Shirai¹, K Shiraishi¹, A Suzuki¹, Y Suzuki¹, A Takeuchi¹, K Tamae¹, K Ueshima¹, H Watanabe¹, Y Yoshida¹, S Obara⁴, A K Ichikawa⁵, D Chernyak², A Kozlov², K Z Nakamura⁶, S Yoshida⁷, Y Takemoto⁸, S Umehara⁸, K Fushimi⁹, K Kotera¹⁰, Y Urano¹⁰, B E Berger^{2

11}, B K Fujikawa^{2

11}, J G Learned¹², J Maricic¹², S N Axani¹³, J Smolsky¹³, Z Fu¹³, L A Winslow¹³, Y Efremenko^{2

14}, H J Karwowski¹⁵, D M Markoff¹⁵, W Tornow^{2

15}, S Dell'Oro¹⁶, T O'Donnell¹⁶, J A Detwiler^{2

17}, S Enomoto^{2

17}, M P Decowski^{2

18}, C Grant¹⁹, A Li^{15

19}, H Song¹⁹; KamLAND-Zen Collaboration

Affiliations

¹ Research Center for Neutrino Science, Tohoku University, Sendai 980-8578, Japan.
² Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan.
³ Graduate Program on Physics for the Universe, Tohoku University, Sendai 980-8578, Japan.
⁴ Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan.
⁵ Department of Physics, Tohoku University, Sendai 980-8578, Japan.
⁶ Kyoto University, Department of Physics, Kyoto 606-8502, Japan.
⁷ Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
⁸ Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047, Japan.
⁹ Department of Physics, Tokushima University, Tokushima 770-8506, Japan.
¹⁰ Graduate School of Integrated Arts and Sciences, Tokushima University, Tokushima 770-8502, Japan.
¹¹ Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
¹² Department of Physics and Astronomy, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA.
¹³ Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
¹⁴ Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA.
¹⁵ Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA; Physics Departments at Duke University, Durham, North Carolina 27708, USA; North Carolina Central University, Durham, North Carolina 27707, USA; and The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
¹⁶ Center for Neutrino Physics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
¹⁷ Center for Experimental Nuclear Physics and Astrophysics, University of Washington, Seattle, Washington 98195, USA.
¹⁸ Nikhef and the University of Amsterdam, Science Park, Amsterdam, Netherlands.
¹⁹ Boston University, Boston, Massachusetts 02215, USA.

PMID: 36800472
DOI: 10.1103/PhysRevLett.130.051801

Abstract

The KamLAND-Zen experiment has provided stringent constraints on the neutrinoless double-beta (0νββ) decay half-life in ^{136}Xe using a xenon-loaded liquid scintillator. We report an improved search using an upgraded detector with almost double the amount of xenon and an ultralow radioactivity container, corresponding to an exposure of 970 kg yr of ^{136}Xe. These new data provide valuable insight into backgrounds, especially from cosmic muon spallation of xenon, and have required the use of novel background rejection techniques. We obtain a lower limit for the 0νββ decay half-life of T_{1/2}^{0ν}>2.3×10^{26} yr at 90% C.L., corresponding to upper limits on the effective Majorana neutrino mass of 36-156 meV using commonly adopted nuclear matrix element calculations.