Neutron-Antineutron Oscillation Search using a 0.37 Megaton\(\cdot\)Year Exposure of Super-Kamiokande

• Published in: arXiv.org 2020-12
• Main Authors: Super-Kamiokande Collaboration, Abe, K, Bronner, C, Imaizumi, S, Ito, H, Kataoka, Y, Okada, T, Orii, A, Pronost, G, Shiozawa, M, Sonoda, Y, Tanaka, H, Yano, T, Akutsu, R, Kajita, T, Xia, J, Labarga, L, Ll Marti, Kearns, E, Raaf, J L, Wan, L, Griskevich, N J, Locke, S, Sobel, H W, Takhistov, V, Hill, J, Kim, J Y, Bodur, B, Drapier, O, Giampaolo, A, Paganini, P, Nakamura, T, Anthony, L H V, Sztuc, A A, Uchida, Y, Catanesi, M G, Radicioni, E, Machado, L N, De Rosa, G, Collazuol, G, Lamoureux, M, Ospina, N, Ludovici, L, Cao, S, Friend, M, Ishida, T, Kobayashi, T, Nakadaira, T, Oyama, Y, Sekiguchi, T, Shiozawa, T, Suzuki, A T, Yamamoto, S, Ichikawa, A K, Mori, M, Wendell, R A, Yasutome, K, Fernandez, P, McCauley, N, Mehta, P, Itow, Y, Tsukada, M, Mijakowski, P, Jung, C K, Wilking, M J, Horai, T, Ito, S, Barrow, D, Cook, L, Goldsack, A, Simpson, C, Wark, D, F Di Lodovico, S Molina Sedgwick, Taani, M, Zsoldos, S, Yang, J Y, McElwee, J M, Thompson, L F, Stone, O, Kim, S B, Nishijima, K, Koshiba, M, Yokoyama, M, Martens, K, Vagins, M R, Yoshida, T, Inomoto, M, Ishitsuka, M, Ohta, K, Shinoki, M, Martin, J F, Towstego, T, Hartz, M, Konaka, A, de Perio, P, Prouse, N W, Xu, B D, Jamieson, B, Pintaudi, G
• Format: Article
• Language: English
• Subjects: Antiparticles; Baryons; Multivariate analysis; Neutrinos; Searching
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2012.02607

As a baryon number violating process with \(\Delta B=2\), neutron-antineutron oscillation (\(n\to\bar n\)) provides a unique test of baryon number conservation. We have performed a search for \(n\to\bar n\) oscillation with bound neutrons in Super-Kamiokande, with the full data set from its first four run periods, representing an exposure of 0.37~Mton-years. The search used a multivariate analysis trained on simulated \(n\to\bar n\) 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 \(\bar n\) appearance lifetime in \(^{16}\)O nuclei of \(3.6\times{10}^{32}\) years and on the neutron-antineutron oscillation time of \(\tau_{n\to\bar n} > 4.7\times10^{8}\)~s at 90\% C.L..