Measurement of the solar neutrino interaction rate below 3.49 MeV in Super-Kamiokande-IV

Year: 2026

Type: article

Abstract: Super-Kamiokande (SK) has observed B 8 solar neutrino elastic scattering at recoil electron kinetic energies ( E kin ) as low as 3.49 MeV to study neutrino flavor conversion within the Sun. At SK-observable energies, these conversions are dominated by the Mikheyev-Smirnov-Wolfenstein effect. An upturn in the electron neutrino survival probability in which vacuum neutrino oscillations become dominant is predicted to occur at lower energies, but radioactive background increases exponentially with decreasing energy. New machine learning approaches provide substantial background reduction below 3.49 MeV such that statistical extraction of solar neutrino interactions becomes feasible. This article presents an analysis of the solar neutrino interaction rate at E kin < 3.49 MeV with the full SK-IV period, using data from a wideband intelligent trigger when available and with a boosted decision tree for event selection. A solar neutrino signal is observed between 2.99 MeV < E kin < 3.49 MeV with 2.76 σ significance and a data to unoscillated Monte Carlo ratio of 0.307 − 0.111 + 0.112 . These additional low-energy data have a negligible effect on the 1 σ intervals of the fits to the solar neutrino energy spectrum but have a noticeable effect on the best fit when using the exponential parametrization.

Source: Physical review. D/Physical review. D.

DOI: 10.1103/yz79-h758

Authors: A. Yankelevich, K. Abe, Y. Asaoka, M. Harada, Y. Hayato, K. Hiraide, T. H. Hung, K. Hosokawa, K. Ieki, M. Ikeda, J. Kameda, Y. Kanemura, Y. Kataoka, S. Miki, S. Mine, M. Miura, S. Moriyama, K. Nakagiri, M. Nakahata, S. Nakayama, Y. Noguchi, G. Pronost, K. Sato, H. Sekiya, R. Shinoda, M. Shiozawa, Y. Suzuki, A. Takeda, Y. Takemoto, H. Tanaka, T. Yano, S. Chen, Y. Itow, T. Kajita, R. Nishijima, K. Okumura, T. Tashiro, T. Tomiya, X. Wang, F. J. de Garay Arcones, P. Fernandez, L. Labarga, D. Samudio, B. Zaldivar, C. Yanagisawa, B. Jargowsky, E. Kearns, J. Mirabito, L. Wan, T. Wester, B. W. Pointon, J. Bian, B. Cortez, N. J. Griskevich, Y. Jiang, M. B. Smy, H. W. Sobel, V. Takhistov, J. Hill, M. C. Jang, S. H. Lee, D. H. Moon, R. G. Park, B. S. Yang, B. Bodur, K. Scholberg, C. W. Walter, A. Beauchêne, O. Drapier, A. Ershova, M. Ferey, E. Le Blévec, Th. A. Mueller, P. Paganini, C. Quach, R. Rogly, T. Nakamura, J. S. Jang, R. P. Litchfield, L. N. Machado, F. J. P. Soler, J. G. Learned, K. Choi, S. Cao, L. H. V. Anthony, N. W. Prouse, M. Scott, Y. Uchida, V. Berardi, N. F. Calabria, M. G. Catanesi, N. Ospina, E. Radicioni, A. Langella, G. De Rosa, G. Collazuol, M. Feltre, M. Mattiazzi, L. Ludovici, M. Gonin, L. Périssé, B. Quilain, S. Horiuchi, A. Kawabata, M. Kobayashi, Y. M. Liu, Y. Maekawa, Y. Nishimura, R. Akutsu, M. Friend, T. Hasegawa, Y. Hino, T. Ishida, T. Kobayashi, M. Jakkapu, T. Matsubara, T. Nakadaira, Y. Oyama, A. Portocarrero Yrey, K. Sakashita, T. Sekiguchi, T. Tsukamoto, N. Bhuiyan, G. T. Burton, F. Di Lodovico, J. Gao, T. Katori, R. Kralik, N. Latham, R. M. Ramsden, V. Siccardi, H. Ito, T. Sone, A. T. Suzuki, Y. Takeuchi, S. Wada, H. Zhong, J. Feng, L. Feng, S. Han, J. Hikida, J. R. Hu, Z. Hu, M. Kawaue, T. Kikawa, T. V. Ngoc, T. Nakaya, R. A. Wendell, S. J. Jenkins, N. McCauley, A. Tarrant, M. Fanì, M. J. Wilking, Z. Xie, Y. Fukuda, H. Menjo, Y. Yoshioka, J. Lagoda, M. Mandal, Y. S. Prabhu, J. Zalipska, M. Mori, J. Jiang, K. Hamaguchi, H. Ishino, Y. Koshio, F. Nakanishi, T. Tada, T. Ishizuka, G. Barr, D. Barrow, L. Cook, S. Samani, D. Wark, A. Holin, F. Nova, S. Jung, J. Yoo, J. E. P. Fannon, L. Kneale, M. Malek, J. M. McElwee, T. Peacock, P. Stowell, M. D. Thiesse, L. F. Thompson, H. Okazawa, S. M. Lakshmi, E. Kwon, M. W. Lee, J. W. Seo, I. Yu, Y. Ashida, A. K. Ichikawa, K. D. Nakamura, S. Abe, S. Goto, S. Kodama, Y. Kong, H. Hayasaki, Y. Masaki, Y. Mizuno, T. Muro, K. Nakagiri, Y. Nakajima, N. Taniuchi, M. Yokoyama, P. de Perio, S. Fujita, C. Jesús-Valls, K. Martens, Ll. Marti, A. D. Santos, K. M. Tsui, M. R. Vagins, J. Xia, S. Izumiyama, M. Kuze, R. Matsumoto, R. Asaka, M. Ishitsuka, M. Sugo, M. Wako, K. Yamauchi, Y. Nakano, F. Cormier, R. Gaur, M. Hartz, A. Konaka, X. Li, B. R. Smithers, S. Chen, Y. Wu, B. D. Xu, A. Q. Zhang, B. Zhang, H. Adhikary, M. Girgus, P. Govindaraj, M. Posiadala-Zezula, S. B. Boyd, R. Edwards, D. Hadley, M. Nicholson, M. O’Flaherty, B. Richards, A. Ali, B. Jamieson, C. Bronner, D. Horiguchi, A. Minamino, Y. Sasaki, R. Shibayama, R. Shimamura

Institutions: University of California, Irvine, The University of Tokyo, Tsinghua University, Nagoya University, Universidad Autónoma de Madrid, City University of New York, Stony Brook University, Boston University, TRIUMF, British Columbia Institute of Technology, High Energy Accelerator Research Organization, California State University System, Chonnam National University, Duke University, Laboratoire Leprince-Ringuet, Gifu University, Gwangju Institute of Science and Technology, University of Glasgow, University of Hawaiʻi at Mānoa, University of Hawaii System, Institute for Basic Science, Imperial College London, Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, University of Padua, Istituto Nazionale di Fisica Nucleare, Sezione di Padova, Istituto Nazionale di Fisica Nucleare, Sezione di Roma I, Sapienza University of Rome, Keio University, King's College London, Kobe University, Kyoto University, University of Liverpool, University of Minnesota, Miyagi University of Education, National Centre for Nuclear Research, Okayama University, Osaka Electro-Communication University, University of Oxford, Rutherford Appleton Laboratory, Seoul National University, University of Sheffield, Shizuoka University of Welfare, University of Silesia in Katowice, Sungkyunkwan University, Tohoku University, Institute of Science Tokyo, Tokyo University of Science, University of Toyama, University of Warsaw, University of Warwick, The University of Winnipeg, Yokohama National University

Language: English

Topic: Neutrino Physics Research

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Awards: G11867378, G187855974, G2683789298, G2818282093, G2907963052, G3049196905, G3297240425, G3634461281, G3831296399, G3837556332, Japan and Europe Network for Neutrino and Intensity Frontier Experimental Research 2, From Super-Kamiokande to Hyper-Kamiokande, G4929234656, G5502277635, G5925907655, G753483755, G7865097842

OpenAlex ID: W7140797029