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Neutron-antineutron oscillation search using a 0.37 megaton-years exposure of Super-Kamiokande

Research output: Contribution to journalArticlepeer-review

(Super-Kamiokande Collaboration)

Original languageEnglish
Article number012008
JournalPhysical Review D
Issue number1
Published21 Jan 2021

Bibliographical note

Funding Information: We gratefully acknowledge the cooperation of the Kamioka Mining and Smelting Company. The Super-Kamiokande experiment has been built and operated from funding by the Japanese Ministry of Education, Culture, Sports, Science and Technology, the U.S. Department of Energy, and the U.S. National Science Foundation. Some of us have been supported by funds from the National Research Foundation of Korea NRF20090083526 (KNRC) funded by the Ministry of Science, ICT, and Future Planning and the Ministry of Education (Grants No. 2018R1D1A3B07050696 and No. 2018R1D1A1B07049158), the Japan Society for the Promotion of Science, the National Natural Science Foundation of China under Grant No. 11620101004, the Spanish Ministry of Science, Universities and Innovation (Grant No. PGC2018-099388-B-I00), the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Scinet and Westgrid consortia of Compute Canada, the National Science Centre, Poland (2015/18/E/ST2/00758), the Science and Technology Facilities Council (STFC) and GridPPP, United Kingdom, the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie Grant Agreement No. 754496, H2020-MSCA-RISE-2018 JENNIFER2 Grant Agreement No. 822070, and H2020-MSCA-RISE-2019 SK2HK Grant Agreement No. 872549. Publisher Copyright: © 2021 authors. Published by the American Physical Society. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

King's Authors


As a baryon number violating process with ΔB=2, neutron-antineutron oscillation (n→n¯) provides a unique test of baryon number conservation. We have performed a search for n→n¯ oscillation with bound neutrons in Super-Kamiokande, with the full dataset from its first four run periods, representing an exposure of 0.37 Mton-years. The search used a multivariate analysis trained on simulated n→n¯ events and atmospheric neutrino backgrounds and resulted in 11 candidate events with an expected background of 9.3 events. In the absence of statistically significant excess, we derived a lower limit on n¯ appearance lifetime in O16 nuclei of 3.6×1032 years and on the neutron-antineutron oscillation time of τn→n¯>4.7×108 s at 90% C.L.

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