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1. Solar neutrino measurements using the full data period of Super-Kamiokande-IV

Author: Collaboration, Super-Kamiokande, Abe, K., Bronner, C., Hayato, Y., Hiraide, K., Hosokawa, K., Ieki, K., Ikeda, M., Imaizumi, S., Iyogi, K., Kameda, J., Kanemura, Y., Kaneshima, R., Kashiwagi, Y., Kataoka, Y., Kato, Y., Kishimoto, Y., Miki, S., Mine, S., Miura, M., Mochizuki, T., Moriyama, S., Nagao, Y., Nakahata, M., Nakano, Y., Nakayama, S., Noguchi, Y., Okada, T., Okamoto, K., Orii, A., Sato, K., Sekiya, H., Shiba, H., Shimizu, K., Shiozawa, M., Sonoda, Y., Suzuki, Y., Takeda, A., Takemoto, Y., Takenaka, A., Tanaka, H., Watanabe, S., Yano, T., Han, S., Kajita, T., Okumura, K., Tashiro, T., Tomiya, T., Wang, R., Wang, X., Yoshida, S., Bravo-Berguno, D., Fernandez, P., Labarga, L., Ospina, N., Zaldivar, B., Pointon, B. W., Blaszczyk, F. d. M., Kachulis, C., Kearns, E., Raaf, J. L., Stone, J. L., Wan, L., Wester, T., Bian, J., Griskevich, N. J., Kropp, W. R., Locke, S., Smy, M. B., Sobel, H. W., Takhistov, V., Weatherly, P., Yankelevich, A., Ganezer, K. S., Hill, J., Jang, M. C., Kim, J. Y., Lee, S., Lim, I. T., Moon, D. H., Park, R. G., Bodur, B., Scholberg, K., Walter, C. W., Beauchene, A., Bernard, L., Coffani, A., Drapier, O., Hedri, S. El, Giampaolo, A., Imber, J., Mueller, Th. A., Paganini, P., Rogly, R., Quilain, B., Santos, A., Nakamura, T., Jang, J. S., Machado, L. N., Learned, J. G., Matsuno, S., Iovine, N., Choi, K., Cao, S., Anthony, L. H. V., Litchfield, R. P., Prouse, N., Marin, D., Scott, M., Sztuc, A. A., Uchida, Y., Berardi, V., Catanesi, M. G., Intonti, R. A., Radicioni, E., Calabria, N. F., De Rosa, G., Langella, A., Collazuol, G., Iacob, F., Lamoureux, M., Mattiazzi, M., Ludovici, L., Gonin, M., Perisse, L., Pronost, G., Fujisawa, C., Maekawa, Y., Nishimura, Y., Okazaki, R., Friend, M., Hasegawa, T., Ishida, T., Jakkapu, M., Kobayashi, T., Matsubara, T., Nakadaira, T., Nakamura, K., Oyama, Y., Sakashita, K., Sekiguchi, T., Tsukamoto, T., Boschi, T., Bhuiyan, N., Burton, G. T., Gao, J., Goldsack, A., Katori, T., Di Lodovico, F., Migenda, J., Sedgwick, S. Molina, Ramsden, R. M., Taani, M., Xie, Z., Zsoldos, S., Abe, KE., Hasegawa, M., Isobe, Y., Kotsar, Y., Miyabe, H., Ozaki, H., Shiozawa, T., Sugimoto, T., Suzuki, A. T., Takagi, Y., Takeuchi, Y., Yamamoto, S., Zhong, H., Ashida, Y., Feng, J., Feng, L., Hayashino, T., Hirota, S., Hu, J. R., Hu, Z., Jiang, M., Kawaue, M., Kikawa, T., Mori, M., Nakamura, KE., Nakaya, T., Wendell, R. A., Yasutome, K., Jenkins, S. J., McCauley, N., Mehta, P., Pritchard, A., Tarrant, A., Wilking, M. J., Fukuda, Y., Itow, Y., Menjo, H., Murase, M., Ninomiya, K., Niwa, T., Tsukada, M., Yoshioka, Y., Frankiewicz, K., Lagoda, J., Mandal, M., Mijakowski, P., Prabhu, Y. S., Zalipska, J., Jiang, J., Jia, M., Jung, C. K., Palomino, J. L., Santucci, G., Shi, W., Vilela, C., Yanagisawa, C., Fukuda, D., Hagiwara, K., Harada, M., Hino, Y., Horai, T., Ishino, H., Ito, S., Kitagawa, H., Koshio, Y., Ma, W., Nakanishi, F., Piplani, N., Sakai, S., Sakuda, M., Tada, T., Tano, T., Xu, C., Yamaguchi, R., Ishizuka, T., Kuno, Y., Barr, G., Barrow, D., Cook, L., Samani, S., Simpson, C., Wark, D., Holin, A. M., Nova, F., Jung, S., Yang, B., Yang, J. Y., Yoo, J., Fannon, J. E. P., Kneale, L., Malek, M., McElwee, J. M., Stone, O., Thiesse, M. D., Thompson, L. F., Wilson, S. T., Okazawa, H., Lakshmi, S. M., Choi, Y., Kim, S. B., Kwon, E., Seo, J. W., Yu, I., Ichikawa, A. K., Tairahune, S., Nishijima, K., Eguchi, A., Iwamoto, K., Nakagiri, K., Nakajima, Y., Ogawa, N., Shima, S., Watanabe, E., Yokoyama, M., Calland, R. G., Fujita, S., Jesus-Valls, C., Junjie, X., Ming, T. K., de Perio, P., Martens, K., Murdoch, M., Vagins, M. R., Izumiyama, S., Kuze, M., Matsumoto, R., Okajima, Y., Tanaka, M., Yoshida, T., Inomoto, M., Ishitsuka, M., Ito, H., Kinoshita, T., Ohta, K., Ommura, Y., Shinoki, M., Shigeta, N., Suganuma, T., Yamaguchi, K., Martin, J. F., Nantais, C. M., Tanaka, H. A., Towstego, T., Gaur, R., Gousy-Leblanc, V., Hartz, M., Konaka, A., Li, X., Chen, S., Xu, B. D., Zhang, B., Berkman, S., Posiadala-Zezula, M., Boyd, S. B., Edwards, R., Hadley, D., Nicholson, M., O'Flaherty, M., Richards, B., Ali, A., Jamieson, B., Walker, J., Amanai, S., Marti, Ll., Minamino, A., Pintaudi, G., Sano, S., Sasaki, R., Suzuki, S., and Wada, K.
Subjects: High Energy Physics - Experiment
Abstract: An analysis of solar neutrino data from the fourth phase of Super-Kamiokande~(SK-IV) from October 2008 to May 2018 is performed and the results are presented. The observation time of the data set of SK-IV corresponds to $2970$~days and the total live time for all four phases is $5805$~days. For more precise solar neutrino measurements, several improvements are applied in this analysis: lowering the data acquisition threshold in May 2015, further reduction of the spallation background using neutron clustering events, precise energy reconstruction considering the time variation of the PMT gain. The observed number of solar neutrino events in $3.49$--$19.49$ MeV electron kinetic energy region during SK-IV is $65,443^{+390}_{-388}\,(\mathrm{stat.})\pm 925\,(\mathrm{syst.})$ events. Corresponding $\mathrm{^{8}B}$ solar neutrino flux is $(2.314 \pm 0.014\, \rm{(stat.)} \pm 0.040 \, \rm{(syst.)}) \times 10^{6}~\mathrm{cm^{-2}\,s^{-1}}$, assuming a pure electron-neutrino flavor component without neutrino oscillations. The flux combined with all SK phases up to SK-IV is $(2.336 \pm 0.011\, \rm{(stat.)} \pm 0.043 \, \rm{(syst.)}) \times 10^{6}~\mathrm{cm^{-2}\,s^{-1}}$. Based on the neutrino oscillation analysis from all solar experiments, including the SK $5805$~days data set, the best-fit neutrino oscillation parameters are $\rm{sin^{2} \theta_{12,\,solar}} = 0.306 \pm 0.013 $ and $\Delta m^{2}_{21,\,\mathrm{solar}} = (6.10^{+ 0.95}_{-0.81}) \times 10^{-5}~\rm{eV}^{2}$, with a deviation of about 1.5$\sigma$ from the $\Delta m^{2}_{21}$ parameter obtained by KamLAND. The best-fit neutrino oscillation parameters obtained from all solar experiments and KamLAND are $\sin^{2} \theta_{12,\,\mathrm{global}} = 0.307 \pm 0.012 $ and $\Delta m^{2}_{21,\,\mathrm{global}} = (7.50^{+ 0.19}_{-0.18}) \times 10^{-5}~\rm{eV}^{2}$., Comment: 47 pages, 61 figures
Published: 2023
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2. Searching for neutrinos from solar flares across solar cycles 23 and 24 with the Super-Kamiokande detector

Author: Okamoto, K., Abe, K., Hayato, Y., Hiraide, K., Hosokawa, K., Ieki, K., Ikeda, M., Kameda, J., Kanemura, Y., Kaneshima, Y., Kataoka, Y., Kashiwagi, Y., Miki, S., Mine, S., Miura, M., Moriyama, S., Nagao, Y., Nakahata, M., Nakano, Y., Nakayama, S., Noguchi, Y., Sato, K., Sekiya, H., Shimizu, K., Shiozawa, M., Shiba, H., Sonoda, Y., Suzuki, Y., Takeda, A., Takemoto, Y., Takenaka, A., Tanaka, H., Watanabe, S., Yano, T., Han, S., Kajita, T., Okumura, K., Tashiro, T., Tomiya, T., Wang, X., Xia, J., Yoshida, S., Megias, G. D., Fernandez, P., Labarga, L., Ospina, N., Zaldivar, B., Pointon, B. W., Kearns, E., Raaf, J. L., Wan, L., Wester, T., Bian, J., Griskevich, N. J., Kropp, W. R., Locke, S., Smy, M. B., Sobel, H. W., Takhistov, V., Yankelevich, A., Hill, J., Kim, J. Y., Lee, S. H., Lim, I. T., Moon, D. H., Park, R. G., Bodur, B., Scholberg, K., Walter, C. W., Beauchene, A., Bernard, L., Coffani, A., Drapier, O., Hedri, S. El, Giampaolo, A., Mueller, Th. A., Santos, A. D., Paganini, P., Quilain, B., Ishizuka, T., Nakamura, T., Jang, J. S., Learned, J. G., Choi, K., Cao, S., Anthony, L. H. V., Martin, D., Scott, M., Sztuc, A. A., Uchida, Y., Berardi, V., Catanesi, M. G., Radicioni, E., Calabria, N. F., Machado, L. N., De Rosa, G., Collazuol, G., Iacob, F., Lamoureux, M., Mattiazzi, M., Ludovici, L., Gonin, M., Pronost, G., Fujisawa, C., Maekawa, Y., Nishimura, Y., Friend, M., Hasegawa, T., Ishida, T., Kobayashi, T., Jakkapu, M., Matsubara, T., Nakadaira, T., Nakamura, K., Oyama, Y., Sakashita, K., Sekiguchi, T., Tsukamoto, T., Bhuiyan, N., Boschi, T., Burton, G. T., Di Lodovico, F., Gao, J., Goldsack, A., Katori, T., Migenda, J., Taani, M., Xie, Z., Zsoldos, S., Kotsar, Y., Ozaki, H., Suzuki, A. T., Takeuchi, Y., Yamamoto, S., Bronner, C., Feng, J., Kikawa, T., Mori, M., Nakaya, T., Wendell, R. A., Yasutome, K., Jenkins, S. J., McCauley, N., Mehta, P., Tarrant, A., Tsui, K. M., Fukuda, Y., Itow, Y., Menjo, H., Ninomiya, K., Lagoda, J., Lakshmi, S. M., Mandal, M., Mijakowski, P., Prabhu, Y. S., Zalipska, J., Jia, M., Jiang, J., Jung, C. K., Vilela, C., Wilking, M. J., Yanagisawa, C., Harada, M., Ishino, H., Ito, S., Kitagawa, H., Koshio, Y., Ma, W., Nakanishi, F., Piplani, N., Sakai, S., Barr, G., Barrow, D., Cook, L., Samani, S., Wark, D., Holin, A., Nova, F., Yang, J. Y., Fannon, J. E. P., Malek, M., McElwee, J. M., Stone, O., Thiesse, M. D., Thompson, L. F., Okazawa, H., Kim, S. B., Kwon, E., Seo, J. W., Yu, I., Ichikawa, A. K., Nakamura, K. D., Tairafune, S., Nishijima, K., Koshiba, M., Iwamoto, K., Nakagiri, K., Nakajima, Y., Shima, S., Taniuchi, N., Yokoyama, M., Martens, K., de Perio, P., Vagins, M. R., Kuze, M., Izumiyama, S., Inomoto, M., Ishitsuka, M., Ito, H., Kinoshita, T., Matsumoto, R., Ommura, Y., Shigeta, N., Shinoki, M., Suganuma, T., Yamauchi, K., Martin, J. F., Tanaka, H. A., Towstego, T., Akutsu, R., Gaur, R., Gousy-Leblanc, V., Hartz, M., Konaka, A., Li, X., Prouse, N. W., Chen, S., Xu, B. D., Zhang, B., Posiadala-Zezula, M., Boyd, S. B., Hadley, D., Nicholson, M., O'Flaherty, M., Richards, B., Ali, A., Jamieson, B., Walker, J., Marti, Ll., Minamino, A., Pintaudi, G., Sano, S., Sasaki, R., Suzuki, S., and Wada, K.
Subjects: Astrophysics - Solar and Stellar Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment, Physics - Space Physics
Abstract: Neutrinos associated with solar flares (solar-flare neutrinos) provide information on particle acceleration mechanisms during the impulsive phase of solar flares. We searched using the Super-Kamiokande detector for neutrinos from solar flares that occurred during solar cycles $23$ and $24$, including the largest solar flare (X28.0) on November 4th, 2003. In order to minimize the background rate we searched for neutrino interactions within narrow time windows coincident with $\gamma$-rays and soft X-rays recorded by satellites. In addition, we performed the first attempt to search for solar-flare neutrinos from solar flares on the invisible side of the Sun by using the emission time of coronal mass ejections (CMEs). By selecting twenty powerful solar flares above X5.0 on the visible side and eight CMEs whose emission speed exceeds $2000$ $\mathrm{km \, s^{-1}}$ on the invisible side from 1996 to 2018, we found two (six) neutrino events coincident with solar flares occurring on the visible (invisible) side of the Sun, with a typical background rate of $0.10$ ($0.62$) events per flare in the MeV-GeV energy range. No significant solar-flare neutrino signal above the estimated background rate was observed. As a result we set the following upper limit on neutrino fluence at the Earth $\mathit{\Phi}<1.1\times10^{6}$ $\mathrm{cm^{-2}}$ at the $90\%$ confidence level for the largest solar flare. The resulting fluence limits allow us to constrain some of the theoretical models for solar-flare neutrino emission., Comment: 36 pages, 18 figures, 9 tables (Figure 12 was replaced because it was incorrect in version 1.)
Published: 2022

3. Neutron Tagging following Atmospheric Neutrino Events in a Water Cherenkov Detector

Author: Abe, K., Haga, Y., Hayato, Y., Hiraide, K., Ieki, K., Ikeda, M., Imaizumi, S., Iyogi, K., Kameda, J., Kanemura, Y., Kataoka, Y., Kato, Y., Kishimoto, Y., Miki, S., Mine, S., Miura, M., Mochizuki, T., Moriyama, S., Nagao, Y., Nakahata, M., Nakajima, T., Nakano, Y., Nakayama, S., Okada, T., Okamoto, K., Orii, A., Sato, K., Sekiya, H., Shiozawa, M., Sonoda, Y., Suzuki, Y., Takeda, A., Takemoto, Y., Takenaka, A., Tanaka, H., Tasaka, S., Tomura, T., Ueno, K., Watanabe, S., Yano, T., Yokozawa, T., Han, S., Irvine, T., Kajita, T., Kametani, I., Kaneyuki, K., Lee, K. P., McLachlan, T., Okumura, K., Richard, E., Tashiro, T., Wang, R., Xia, J., Megias, G. D., Bravo-Berguño, D., Labarga, L., Zaldivar, B., Goldhaber, M., Blaszczyk, F. d. M., Gustafson, J., Kachulis, C., Kearns, E., Raaf, J. L., Stone, J. L., Sulak, L. R., Sussman, S., Wan, L., Wester, T., Pointon, B. W., Bian, J., Carminati, G., Elnimr, M., Griskevich, N. J., Kropp, W. R., Locke, S., Renshaw, A., Smy, M. B., Sobel, H. W., Takhistov, V., Weatherly, P., Ganezer, K. S., Hartfiel, B. L., Hill, J., Keig, W. E., Hong, N., Kim, J. Y., Lim, I. T., Park, R. G., Akiri, T., Bodur, B., Himmel, A., Li, Z., O'Sullivan, E., Scholberg, K., Walter, C. W., Wongjirad, T., Bernard, L., Coffani, A., Drapier, O., Hedri, S. El, Giampaolo, A., Imber, J., Mueller, Th. A., Paganini, P., Quilain, B., Ishizuka, T., Nakamura, T., Jang, J. S., Choi, K., Learned, J. G., Matsuno, S., Smith, S. N., Amey, J., Anthony, L. H. V., Litchfield, R. P., Ma, W. Y., Marin, D., Sztuc, A. A., Uchida, Y., Wascko, M. O., Berardi, V., Catanesi, M. G., Intonti, R. A., Radicioni, E., Calabria, N. F., De Rosa, G., Machado, L. N., Collazuol, G., Iacob, F., Lamoureux, M., Ospina, N., Ludovici, L., Gonin, M., Pronost, G., Maekawa, Y., Nishimura, Y., Cao, S., Friend, M., Hasegawa, T., Ishida, T., Ishii, T., Jakkapu, M., Kobayashi, T., Matsubara, T., Nakadaira, T., Nakamura, K., Oyama, Y., Sakashita, K., Sekiguchi, T., Tsukamoto, T., Boschi, T., Di Lodovico, F., Migenda, J., Sedgwick, S. Molina, Taani, M., Zsoldos, S., Abe, KE., Hasegawa, M., Isobe, Y., Kotsar, Y., Miyabe, H., Ozaki, H., Shiozawa, T., Sugimoto, T., Suzuki, A. T., Takeuchi, Y., Yamamoto, S., Ali, A., Ashida, Y., Bronner, C., Feng, J., Hayashino, T., Hiraki, T., Hirota, S., Huang, K., Jiang, M., Kikawa, T., Mori, M., Murakami, A., Nakamura, KE., Nakaya, T., Patel, N. D., Suzuki, K., Takahashi, S., Tateishi, K., Wendell, R. A., Yasutome, K., Fernandez, P., McCauley, N., Mehta, P., Pritchard, A., Tsui, K. M., Fukuda, Y., Itow, Y., Menjo, H., Mitsuka, G., Murase, M., Muto, F., Niwa, T., Tsukada, T. Suzuki M., Frankiewicz, K., Mijakowski, P., Hignight, J., Jiang, J., Jung, C. K., Li, X., Palomino, J. L., Santucci, G., Vilela, C., Wilking, M. J., Yanagisawa, C., Fukuda, D., Hagiwara, K., Harada, M., Horai, T., Ishino, H., Ito, S., Kayano, T., Kibayashi, A., Kitagawa, H., Koshio, Y., Ma, W., Mori, T., Nagata, H., Piplani, N., Sakai, S., Sakuda, M., Takahira, Y., Xu, C., Yamaguchi, R., Kuno, Y., Barr, G., Barrow, D., Cook, L., Goldsack, A., Samani, S., Simpson, C., Wark, D., Nova, F., Tacik, R., Yang, J. Y., Cole, A., Jenkins, S. J., Malek, M., McElwee, J. M., Stone, O., Thiesse, M. D., Thompson, L. F., Okazawa, H., Choi, Y., Kim, S. B., Yu, I., Ichikawa, A. K., Ito, K., Nishijima, K., Calland, R. G., de Perio, P., Martens, K., Murdoch, M., Vagins, M. R., Koshiba, M., Totsuka, Y., Iwamoto, K., Nakajima, Y., Ogawa, N., Suda, Y., Yokoyama, M., Hamabe, D., Izumiyama, S., Kuze, M., Okajima, Y., Tanaka, M., Yoshida, T., Inomoto, M., Ishitsuka, M., Ito, H., Matsumoto, R., Ohta, K., Shinoki, M., Martin, J. F., Nantais, C. M., Tanaka, H. A., Towstego, T., Akutsu, R., Hartz, M., Konaka, A., Prouse, N. W., Chen, S., Xu, B. D., Zhang, Y., Berkman, S., Tobayama, S., Connolly, K., Wilkes, R. J., Posiadala-Zezula, M., Hadley, D., Richards, B., Jamieson, B., Walker, J., Marti, Ll., Minamino, A., Pintaudi, G., Sano, S., and Sasaki, R.
Subjects: High Energy Physics - Experiment, Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Instrumentation and Detectors
Abstract: We present the development of neutron-tagging techniques in Super-Kamiokande IV using a neural network analysis. The detection efficiency of neutron capture on hydrogen is estimated to be 26%, with a mis-tag rate of 0.016 per neutrino event. The uncertainty of the tagging efficiency is estimated to be 9.0%. Measurement of the tagging efficiency with data from an Americium-Beryllium calibration agrees with this value within 10%. The tagging procedure was performed on 3,244.4 days of SK-IV atmospheric neutrino data, identifying 18,091 neutrons in 26,473 neutrino events. The fitted neutron capture lifetime was measured as 218 \pm 9 \mu s.
Published: 2022
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4. Search for supernova bursts in Super-Kamiokande IV

Author: collaboration, The Super-Kamiokande, Mori, M., Abe, K., Hayato, Y., Hiraide, K., Ieki, K., Ikeda, M., Imaizumi, S., Kameda, J., Kanemura, Y., Kaneshima, R., Kashiwagi, Y., Kataoka, Y., Miki, S., Mine, S., Miura, M., Moriyama, S., Nagao, Y., Nakahata, M., Nakano, Y., Nakayama, S., Noguchi, Y., Okada, T., Okamoto, K., Orii, A., Sato, K., Sekiya, H., Shiba, H., Shimizu, K., Shiozawa, M., Sonoda, Y., Suzuki, Y., Takeda, A., Takemoto, Y., Takenaka, A., Tanaka, H., Tomiya, T., Watanabe, S., Yano, T., Yoshida, S., Han, S., Kajita, T., Okumura, K., Tashiro, T., Wang, X., Xia, J., Megias, G. D., Bravo-Berguno, D., Fernandez, P., Labarga, L., Ospina, N., Zaldivar, B., Zsoldos, S., Pointon, B. W., Blaszczyk, F. d. M., Kearns, E., Raaf, J. L., Stone, J. L., Wan, L., Wester, T., Bian, J., Griskevich, N. J., Kropp, W. R., Locke, S., Smy, M. B., Sobel, H. W., Takhistov, V., Yankelevich, Hill, J., Kim, J. Y., Lim, I. T., Park, R. G., Bodur, B., Scholberg, K., Walter, C. W., Bernard, L., Coffani, A., Drapier, O., Hedri, S. El, Giampaolo, A., Mueller, Th. A., Paganini, P., Quilain, B., Santos, A. D., Ishizuka, T., Nakamura, T., Jang, J. S., Learned, J. G., Anthony, L. H. V., Martin, D., Scott, M., Sztuc, A. A., Uchida, Y., Berardi, V., Catanesi, M. G., Radicioni, E., Calabria, N. F., Machado, L. N., De Rosa, G., Collazuol, G., Iacob, F., Lamoureux, M., Mattiazzi, M., Ludovici, L., Gonin, M., Pronost, G., Maekawa, Y., Nishimura, Y., Fujisawa, C., Friend, M., Hasegawa, T., Ishida, T., Kobayashi, T., Jakkapu, M., Matsubara, T., Nakadaira, T., Nakamura, K., Oyama, Y., Sakashita, K., Sekiguchi, T., Tsukamoto, T., Ozaki, H., Shiozawa, T., Suzuki, A. T., Takeuchi, Y., Yamamoto, S., Kotsar, Y., Ashida, Y., Bronner, C., Feng, J., Hirota, S., Kikawa, T., Nakaya, T., Wendell, R. A., Yasutome, K., McCauley, N., Mehta, P., Tsui, K. M., Fukuda, Y., Itow, Y., Menjo, H., Ninomiya, K., Niwa, T., Tsukada, M., Lagoda, J., Lakshmi, S. M., Mijakowski, P., Zalipska, J., Mandal, M., Prabhu, Y. S., Jiang, J., Jung, C. K., Vilela, C., Wilking, M. J., Yanagisawa, C., Jia, M., Hagiwara, K., Harada, M., Horai, T., Ishino, H., Ito, S., Kitagawa, H., Koshio, Y., Ma, W., Nakanishi, F., Piplani, N., Sakai, S., Barr, G., Barrow, D., Cook, L., Samani, S., Wark, D., Nova, F., Boschi, T., Gao, J., Goldsack, A., Katori, T., Di Lodovico, F., Migenda, J., Taani, M., Yang, J. Y., Jenkins, S. J., Malek, M., McElwee, J. M., Stone, O., Thiesse, M. D., Thompson, L. F., Okazawa, H., Kim, S. B., Seo, J. W., Yu, I., Nishijima, K., Koshiba, M., Nakagiri, K., Nakajima, Y., Iwamoto, K., Taniuchi, N., Yokoyama, M., Martens, K., de Perio, P., Vagins, M. R., Kuze, M., Izumiyama, S., Yoshida, T., Inomoto, M., Ishitsuka, M., Ito, H., Kinoshita, T., Matsumoto, R., Ohta, K., Ommura, Y., Shigeta, N., Shinoki, M., Suganuma, T., Yamauchi, K., Martin, J. F., Tanaka, H. A., Towstego, T., Akutsu, R., Gousy-Leblanc, V., Hartz, M., Konaka, A., Prouse, N. W., Chen, S., Xu, B. D., Zhang, B., Posiadala-Zezula, M., Hadley, D., Nicholson, M., Flaherty, M. O', Richards, B., Ali, A., Jamieson, B., Walker, J., Marti, Ll., Minamino, A., Pintaudi, G., Sasaki, R., Sano, S., Suzuki, S., Wada, K., Cao, S., Ichikawa, A., Nakamura, K. D., and Tairafun, S.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract: Super-Kamiokande has been searching for neutrino bursts characteristic of core-collapse supernovae continuously, in real time, since the start of operations in 1996. The present work focuses on detecting more distant supernovae whose event rate may be too small to trigger in real time, but may be identified using an offline approach. The analysis of data collected from 2008 to 2018 found no evidence of distant supernovae bursts. This establishes an upper limit of 0.29 year$^{-1}$ on the rate of core-collapse supernovae out to 100 kpc at 90% C.L.. For supernovae that fail to explode and collapse directly to black holes the limit reaches to 300 kpc.
Published: 2022
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5. Pre-Supernova Alert System for Super-Kamiokande

Author: Collaboration, Super-Kamiokande, Machado, L. N., Abe, K., Hayato, Y., Hiraide, K., Ieki, K., Ikeda, M., Kameda, J., Kanemura, Y., Kaneshima, R., Kashiwagi, Y., Kataoka, Y., Miki, S., Mine, S., Miura, M., Moriyama, S., Nakano, Y., Nakahata, M., Nakayama, S., Noguchi, Y., Okamoto, K., Sato, K., Sekiya, H., Shiba, H., Shimizu, K., Shiozawa, M., Sonoda, Y., Suzuki, Y., Takeda, A., Takemoto, Y., Takenaka, A., Tanaka, H., Watanabe, S., Yano, T., de Perio, P., Martens, K., Vagins, M. R., Bian, J., Griskevich, N. J., Kropp, W. R., Locke, S., Smy, M. B., Sobel, H. W., Takhistov, V., Yankelevich, A., Han, S., Kajita, T., Okumura, K., Tashiro, T., Tomiya, T., Wang, X., Xia, J., Yoshida, S., Megias, G. D., Fernandez, P., Labarga, L., Ospina, N., Zaldivar, B., Pointon, B. W., Akutsu, R., Gousy-Leblanc, V., Hartz, M., Konaka, A., Prouse, N. W., Kearns, E., Raaf, J. L., Wan, L., Wester, T., Hill, J., Kim, J. Y., Lim, I. T., Park, R. G., Bodur, B., Scholberg, K., Walter, C. W., Bernard, L., Coffani, A., Drapier, O., Hedri, S. El, Giampaolo, A., Mueller, Th. A., Santos, A. D., Paganini, P., Quilain, B., Ishizuka, T., Nakamura, T., Jang, J. S., Learned, J. G., Cao, S., Choi, K., Anthony, L. H. V., Martin, D., Scott, M., Sztuc, A. A., Uchida, Y., Berardi, V., Catanesi, M. G., Radicioni, E., Calabria, N. F., De Rosa, G., Collazuol, G., Iacob, F., Lamoureux, M., Mattiazzi, M., Ludovici, L., Gonin, M., Pronost, G., Fujisawa, C., Maekawa, Y., Nishimura, Y., Sasaki, R., Friend, M., Hasegawa, T., Ishida, T., Jakkapu, M., Kobayashi, T., Matsubara, T., Nakadaira, T., Nakamura, K., Oyama, Y., Sakashita, K., Sekiguchi, T., Tsukamoto, T., Boschi, T., Di Lodovico, F., Gao, J., Goldsack, A., Katori, T., Migenda, J., Taani, M., Zsoldos, S., Kotsar, Y., Ozaki, H., Suzuki, A. T., Takeuchi, Y., Yaamoto, S., Bronner, C., Feng, J., Kikawa, T., Mori, M., Nakaya, T., Wendell, R. A., Yasutome, K., Jenkins, S. J., McCauley, N., Mehta, P., Tsui, K. M., Fukuda, Y., Itow, Y., Menjo, H., Ninomiya, K., Lagoda, J., Lakshmi, S. M., Mandal, M., Mijakowski, P., Prabhu, Y. S., Zalipska, J., Jia, M., Jiang, J., Jung, C. K., Wilking, M. J., Yanagisawa, C., Harada, M., Ishino, H., Ito, S., Kitagawa, H., Koshio, Y., Ma, W., Nakanishi, F., Sakai, S., Barr, G., Barrow, D., Cook, L., Samani, S., Wark, D., Nova, F., Yang, J. Y., Malek, M., McElwee, J. M., Stone, O., Thiesse, M. D., Thompson, L. F., Okazawa, H., Kim, S. B., Seo, J. W., Yu, I., Ichikawa, A. K., Nakamura, K. D., Tairafune, S., Nishijima, K., Iwamoto, K., Nakagiri, K., Nakajima, Y., Taniuchi, N., Yokoyama, M., Izumiyama, S., Kuze, M., Inomoto, M., Ishitsuka, M., Ito, H., Kinoshita, T., Matsumoto, R., Ommura, Y., Shigeta, N., Shinoki, M., Suganuma, T., Yonenaga, M., Martin, J. F., Tanaka, H. A., Towstego, T., Chen, S., Xu, B. D., Zhang, B., Posiadala-Zezula, M., Hadley, D., Nicholson, M., O'Flaherty, M., Richards, B., Ali, A., Jamieson, B., Marti, Ll., Minamino, A., Pintaudi, G., Sano, S., Suzuki, S., and Wada, K.
Subjects: High Energy Physics - Experiment, Astrophysics - High Energy Astrophysical Phenomena, Physics - Instrumentation and Detectors
Abstract: In 2020, the Super-Kamiokande (SK) experiment moved to a new stage (SK-Gd) in which gadolinium (Gd) sulfate octahydrate was added to the water in the detector, enhancing the efficiency to detect thermal neutrons and consequently improving the sensitivity to low energy electron anti-neutrinos from inverse beta decay (IBD) interactions. SK-Gd has the potential to provide early alerts of incipient core-collapse supernovae through detection of electron anti-neutrinos from thermal and nuclear processes responsible for the cooling of massive stars before the gravitational collapse of their cores. These pre-supernova neutrinos emitted during the silicon burning phase can exceed the energy threshold for IBD reactions. We present the sensitivity of SK-Gd to pre-supernova stars and the techniques used for the development of a pre-supernova alarm based on the detection of these neutrinos in SK, as well as prospects for future SK-Gd phases with higher concentrations of Gd. For the current SK-Gd phase, high-confidence alerts for Betelgeuse could be issued up to nine hours in advance of the core-collapse itself., Comment: 20 pages
Published: 2022
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6. Testing Non-Standard Interactions Between Solar Neutrinos and Quarks with Super-Kamiokande

Author: Collaboration, Super-Kamiokande, Weatherly, P., Abe, K., Bronner, C., Hayato, Y., Hiraide, K., Ikeda, M., Iyogi, K., Kameda, J., Kanemura, Y., Kataoka, Y., Kato, Y., Kishimoto, Y., Miki, S., Miura, M., Moriyama, S., Mochizuki, T., Nakahata, M., Nakano, Y., Nakayama, S., Okada, T., Okamoto, K., Orii, A., Pronost, G., Sato, K., Sekiya, H., Shiozawa, M., Sonoda, Y., Suzuki, Y., Takeda, A., Takemoto, Y., Takenaka, A., Tanaka, H., Tasaka, S., Wang, X., Watanabe, S., Yano, T., Han, S., Kajita, T., Kaneyuki, K., Okumura, K., Tashiro, T., Wang, R., Xia, J., Megias, G. D., Labarga, L., Zaldivar, B., Pointon, B. W., Blaszczyk, F. d. M., Kachulis, C., Kearns, E., Raaf, J. L., Stone, J. L., Sulak, L. R., Sussman, S., Wan, L., Wester, T., Berkman, S., Tobayama, S., Bian, J., Elnimr, M., Griskevich, N. J., Kropp, W. R., Locke, S., Mine, S., Smy, M. B., Sobel, H. W., Takhistov, V., Yankelevich, A., Ganezer, K. S., Hill, J., Kim, J. Y., Lim, I. T., Park, R. G., Bodur, B., Li, Z., Scholberg, K., Walter, C. W., Bernard, L., Coffani, A., Drapier, O., Giampaolo, A., Hedri, S. El, Imber, J., Mueller, Th. A., Paganini, P., Quilain, B., Santos, A. D., Ishizuka, T., Nakamura, T., Jang, J. S., Learned, J. G., Matsuno, S., Cao, S., Amey, J., Anthony, L. H. V., Litchfield, R. P., Ma, W. Y., Martin, D., Scott, M., Sztuc, A. A., Uchida, Y., Wascko, M. O., Berardi, V., Catanesi, M. G., Intonti, R. A., Radicioni, E., Calabria, N. F., Machado, L. N., De Rosa, G., Collazuol, G., Iacob, F., Lamoureux, M., Mattiazzi, M., Ospina, N., Ludovici, L., Gonin, M., Maekawa, Y., Nishimura, Y., Friend, M., Hasegawa, T., Ishida, T., Jakkapu, M., Kobayashi, T., Matsubara, T., Nakadaira, T., Nakamura, K., Oyama, Y., Sakashita, K., Sekiguchi, T., Tsukamoto, T., Boschi, T., Di Lodovico, F., Gao, J., Katori, T., Migenda, J., Taani, M., Zsoldos, S., Abe, KE., Hasegawa, M., Isobe, Y., Kotsar, Y., Miyabe, H., Ozaki, H., Sugimoto, T., Suzuki, A. T., Takeuchi, Y., Yamamoto, S., Ashida, Y., Feng, J., Hayashino, T., Hirota, S., Jiang, M., Kikawa, T., Mori, M., Nakaya, T., Wendell, R. A., Yasutome, K., Fernandez, P., McCauley, N., Mehta, P., Pritchard, A., Tsui, K. M., Fukuda, Y., Itow, Y., Menjo, H., Murase, M., Frankiewicz, K., Lagoda, J., Lakshmi, S. M., Mandal, M., Mijakowski, P., Prabhu, Y. S., Zalipska, J., Jia, M., Jiang, J., Jung, C. K., Li, X., Palomino, J. L., Santucci, G., Vilela, C., Wilking, M. J., Yanagisawa, C., Fukuda, D., Hagiwara, K., Harada, M., Ishino, H., Ito, S., Kitagawa, H., Koshio, Y., Ma, W., Sakai, S., Sakuda, M., Takahira, Y., Xu, C., Kuno, Y., Barr, G., Barrow, D., Cook, L., Goldsack, A., Samani, S., Simpson, C., Wark, D., Sedgwick, S. Molina, Tacik, R., Nova, F., Yang, J. Y., Jenkins, S. J., Malek, M., McElwee, J. M., Stone, O., Thiesse, M. D., Thompson, L. F., Okazawa, H., Choi, Y., Kim, S. B., Seo, J. W., Yu, I., Ichikawa, A., Nakamura, K. D., Nishijima, K., Koshiba, M., Iwamoto, K., Nakagiri, K., Nakajima, Y., Suda, Y., Taniuchi, N., Yokoyama, M., Martens, K., Murdoch, M., Vagins, M. R., Hamabe, D., Izumiyama, S., Kuze, M., Okajima, Y., Yoshida, T., Inomoto, M., Ishitsuka, M., Ito, H., Kinoshita, T., Matsumoto, R., Shinoki, M., Suganuma, T., Yonenaga, M., Martin, J. F., Nantais, C. M., Tanaka, H. A., Towstego, T., Akutsu, R., de Perio, P., Gousy-Leblanc, V., Hartz, M., Konaka, A., Prouse, N. W., Chen, S., Xu, B. D., Zhang, B., Posiadala-Zezula, M., Hadley, D., Nicholson, M., O'Flaherty, M., Richards, B., Ali, A., Jamieson, B., Giorgio, P., Marti, Ll., Minamino, A., Pintaudi, G., Sano, S., Sasaki, R., and Wada, K.
Subjects: High Energy Physics - Experiment, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics
Abstract: Non-Standard Interactions (NSI) between neutrinos and matter affect the neutrino flavor oscillations. Due to the high matter density in the core of the Sun, solar neutrinos are suited to probe these interactions. Using the $277$ kton-yr exposure of Super-Kamiokande to $^{8}$B solar neutrinos, we search for the presence of NSI. Our data favors the presence of NSI with down quarks at 1.8$\sigma$, and with up quarks at 1.6$\sigma$, with the best fit NSI parameters being ($\epsilon_{11}^{d},\epsilon_{12}^{d}$) = (-3.3, -3.1) for $d$-quarks and ($\epsilon_{11}^{u},\epsilon_{12}^{u}$) = (-2.5, -3.1) for $u$-quarks. After combining with data from the Sudbury Neutrino Observatory and Borexino, the significance increases by 0.1$\sigma$., Comment: Author: Pierce Weatherly 25 pages. To be submitted to Physical Review D
Published: 2022

7. New Methods and Simulations for Cosmogenic Induced Spallation Removal in Super-Kamiokande-IV

Author: Collaboration, Super-Kamiokande, Locke, S., Coffani, A., Abe, K., Bronner, C., Hayato, Y., Ikeda, M., Imaizumi, S., Ito, H., Kameda, J., Kataoka, Y., Miura, M., Moriyama, S., Nagao, Y., Nakahata, M., Nakajima, Y., Nakayama, S., Okada, T., Okamoto, K., Orii, A., Pronost, G., Sekiya, H., Shiozawa, M., Sonoda, Y., Suzuki, Y., Takeda, A., Takemoto, Y., Takenaka, A., Tanaka, H., Yano, T., Hirade, K., Kanemura, Y., Miki, S., Watabe, S., Han, S., Kajita, T., Okumura, K., Tashiro, T., Xia, J., Wang, X., Megias, G. D., Bravo-Berguño, D., Labarga, L., Marti, Ll., Zaldivar, B., Pointon, B. W., Blaszczyk, F. d. M., Kearns, E., Raaf, J. L., Stone, J. L., Wan, L., Wester, T., Bian, J., Griskevich, N. J., Kropp, W. R., Mine, S., Yankelevic, A., Smy, M. B., Sobel, H. W., Takhistov, V., Hill, J., Kim, J. Y., Lim, I. T., Park, R. G., Bodur, B., Scholberg, K., Walter, C. W., Bernard, L., Drapier, O., Hedri, S. El, Giampaolo, A., Gonin, M., Mueller, Th. A., Paganini, P., Quilain, B., Santos, A. D., Ishizuka, T., Nakamura, T., Jang, J. S., Learned, J. G., Anthony, L. H. V., Sztuc, A. A., Uchida, Y., Martin, D., Scott, M., Berardi, V., Catanesi, M. G., Radicioni, E., Calabria, N. F., Machado, L. N., De Rosa, G., Collazuol, G., Iacob, F., Lamoureux, M., Ospina, N., Mattiazzi, M., Ludovici, L., Nishimura, Y., Maewaka, Y., Cao, S., Friend, M., Hasegawa, T., Ishida, T., Kobayashi, T., Jakkapu, M., Matsubara, T., Nakadaira, T., Nakamura, K., Oyama, Y., Sakashita, K., Sekiguchi, T., Tsukamoto, T., Nakano, Y., Shiozawa, T., Suzuki, A. T., Takeuchi, Y., Yamamoto, S., Kotsar, Y., Ozaki, H., Ali, A., Ashida, Y., Feng, J., Hirota, S., Ichikawa, A. K., Kikawa, T., Mori, M., Nakaya, T., Wendell, R. A., Yasutome, K., Fernandez, P., McCauley, N., Mehta, P., Tsui, K. M., Fukuda, Y., Itow, Y., Menjo, H., Niwa, T., Sato, K., Tsukada, M., Mijakowski, P., Lagoda, J., Lakshmi, S. M., Zalipska, J., Jung, C. K., Vilela, C., Wilking, M. J., Yanagisawa, C., Jiang, J., Hagiwara, K., Harada, M., Horai, T., Ishino, H., Ito, S., Koshio, Y., Ma, W., Piplani, N., Sakai, S., Kitagawa, H., Barr, G., Barrow, D., Cook, L., Goldsack, A., Samani, S., Wark, D., Nova, F., Boschi, T., Di Lodovico, F., Taani, M., Zsoldos, S., Gao, J., Migenda, J., Yang, J. Y., Jenkins, S. J., Malek, M., McElwee, J. M., Stone, O., Thiesse, M. D., Thompson, L. F., Okazawa, H., Kim, S. B., Yu, I., Seo, J. W., Nishijima, K., Koshiba, M., Iwamoto, K., Ogawa, N., Yokoyama, M., Martens, K., Vagins, M. R., Nakagiri, K., Kuze, M., Izumiyama, S., Yoshida, T., Inomoto, M., Ishitsuka, M., Matsumoto, R., Ohta, K., Shinoki, M., Suganuma, T., Kinoshita, T., Martin, J. F., Tanaka, H. A., Towstego, T., Akutsu, R., Hartz, M., Konaka, A., de Perio, P., Prouse, N. W., Chen, S., Xu, B. D., Zhang, Y., Posiadala-Zezula, M., Richards, B., Jamieson, B., Walker, J., Minamino, A., Pintaudi, G., and Sasaki, R.
Subjects: High Energy Physics - Experiment, Astrophysics - High Energy Astrophysical Phenomena
Abstract: Radioactivity induced by cosmic muon spallation is a dominant source of backgrounds for $\mathcal{O}(10)~$MeV neutrino interactions in water Cherenkov detectors. In particular, it is crucial to reduce backgrounds to measure the solar neutrino spectrum and find neutrino interactions from distant supernovae. In this paper we introduce new techniques to locate muon-induced hadronic showers and efficiently reject spallation backgrounds. Applying these techniques to the solar neutrino analysis with an exposure of $2790\times22.5$~kton.day increases the signal efficiency by $12.6\%$, approximately corresponding to an additional year of detector running. Furthermore, we present the first spallation simulation at SK, where we model hadronic interactions using FLUKA. The agreement between the isotope yields and shower pattern in this simulation and in the data gives confidence in the accuracy of this simulation, and thus opens the door to use it to optimize muon spallation removal in new data with gadolinium-enhanced neutron capture detection.
Published: 2021

8. Diffuse Supernova Neutrino Background Search at Super-Kamiokande

Author: Collaboration, Super-Kamiokande, Abe, K., Bronner, C., Hayato, Y., Hiraide, K., Ikeda, M., Imaizumi, S., Kameda, J., Kanemura, Y., Kataoka, Y., Miki, S., Miura, M., Moriyama, S., Nagao, Y., Nakahata, M., Nakayama, S., Okada, T., Okamoto, K., Orii, A., Pronost, G., Sekiya, H., Shiozawa, M., Sonoda, Y., Suzuki, Y., Takeda, A., Takemoto, Y., Takenaka, A., Tanaka, H., Watanabe, S., Yano, T., Han, S., Kajita, T., Okumura, K., Tashiro, T., Xia, J., Megias, G. D., Bravo-Bergu, D., Labarga, L., Marti, Ll., Zaldivar, B., Pointon, B. W., Blaszczyk, F. d. M., Kearns, E., Raaf, J. L., Stone, J. L., Wan, L., Wester, T., Bian, J., Griskevich, N. J., Kropp, W. R., Locke, S., Mine, S., Smy, M. B., Sobel, H. W., Takhistov, V., Hill, J., Kim, J. Y., Lim, I. T., Park, R. G., Bodur, B., Scholberg, K., Walter, C. W., Cao, S., Bernard, L., Coffani, A., Drapier, O., Hedri, S. El, Giampaolo, A., Gonin, M., Mueller, Th. A., Paganini, P., Quilain, B., Ishizuka, T., Nakamura, T., Jang, J. S., Learned, J. G., Anthony, L. H. V., Martin, D., Scott, M., Sztuc, A. A., Uchida, Y., Berardi, V., Catanesi, M. G., Radicioni, E., Calabria, N. F., Machado, L. N., De Rosa, G., Collazuol, G., Iacob, F., Lamoureux, M., Mattiazzi, M., Ospina, N., Ludovici, L., Maekawa, Y., Nishimura, Y., Friend, M., Hasegawa, T., Ishida, T., Kobayashi, T., Jakkapu, M., Matsubara, T., Nakadaira, T., Nakamura, K., Oyama, Y., Sakashita, K., Sekiguchi, T., Tsukamoto, T., Kotsar, Y., Nakano, Y., Ozaki, H., Shiozawa, T., Suzuki, A. T., Takeuchi, Y., Yamamoto, S., Ali, A., Ashida, Y., Feng, J., Hirota, S., Kikawa, T., Mori, M., Nakaya, T., Wendell, R. A., Yasutome, K., Fernandez, P., McCauley, N., Mehta, P., Tsui, K. M., Fukuda, Y., Itow, Y., Menjo, H., Niwa, T., Sato, K., Tsukada, M., Lagoda, J., Lakshmi, S. M., Mijakowski, P., Zalipska, J., Jiang, J., Jung, C. K., Vilela, C., Wilking, M. J., Yanagisawa, C., Hagiwara, K., Harada, M., Horai, T., Ishino, H., Ito, S., Kitagawa, H., Koshio, Y., Ma, W., Piplani, N., Sakai, S., Barr, G., Barrow, D., Cook, L., Goldsack, A., Samani, S., Wark, D., Nova, F., Boschi, T., Di Lodovico, F., Gao, J., Migenda, J., Taani, M., Zsoldos, S., Yang, J. Y., Jenkins, S. J., Malek, M., McElwee, J. M., Stone, O., Thiesse, M. D., Thompson, L. F., Okazawa, H., Kim, S. B., Seo, J. W., Yu, I., Nishijima, K., Koshiba, M., Iwamoto, K., Nakagiri, K., Nakajima, Y., Ogawa, N., Yokoyama, M., Martens, K., Vagins, M. R., Kuze, M., Izumiyama, S., Yoshida, T., Inomoto, M., Ishitsuka, M., Ito, H., Kinoshita, T., Matsumoto, R., Ohta, K., Shinoki, M., Suganuma, T., Ichikawa, A. K., Martin, J. F., Tanaka, H. A., Towstego, T., Akutsu, R., Gousy-Leblanc, V., Hartz, M., Konaka, A., de Perio, P., Prouse, N. W., Chen, S., Xu, B. D., Zhang, Y., Posiadala-Zezula, M., Hadley, D., O'Flaherty, M., Richards, B., Jamieson, B., Walker, J., Minamino, A., Pintaudi, G., Sano, S., and Sasaki, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract: A new search for the diffuse supernova neutrino background (DSNB) flux has been conducted at Super-Kamiokande (SK), with a $22.5\times2970$-kton$\cdot$day exposure from its fourth operational phase IV. The new analysis improves on the existing background reduction techniques and systematic uncertainties and takes advantage of an improved neutron tagging algorithm to lower the energy threshold compared to the previous phases of SK. This allows for setting the world's most stringent upper limit on the extraterrestrial $\bar{\nu}_e$ flux, for neutrino energies below 31.3 MeV. The SK-IV results are combined with the ones from the first three phases of SK to perform a joint analysis using $22.5\times5823$ kton$\cdot$days of data. This analysis has the world's best sensitivity to the DSNB $\bar{\nu}_e$ flux, comparable to the predictions from various models. For neutrino energies larger than 17.3 MeV, the new combined $90\%$ C.L. upper limits on the DSNB $\bar{\nu}_e$ flux lie around $2.7$ cm$^{-2}$$\cdot$$\text{sec}^{-1}$, strongly disfavoring the most optimistic predictions. Finally, potentialities of the gadolinium phase of SK and the future Hyper-Kamiokande experiment are discussed., Comment: 42 pages, 37 figures, 14 tables
Published: 2021
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9. First Gadolinium Loading to Super-Kamiokande

Author: Abe, K., Bronner, C., Hayato, Y., Hiraide, K., Ikeda, M., Imaizumi, S., Kameda, J., Kanemura, Y., Kataoka, Y., Miki, S., Miura, M., Moriyama, S., Nagao, Y., Nakahata, M., Nakayama, S., Okada, T., Okamoto, K., Orii, A., Pronost, G., Sekiya, H., Shiozawa, M., Sonoda, Y., Suzuki, Y., Takeda, A., Takemoto, Y., Takenaka, A., Tanaka, H., Watanabe, S., Yano, T., Han, S., Kajita, T., Okumura, K., Tashiro, T., Xia, J., Megias, G. D., Bravo-Berguno, D., Labarga, L., Marti, Ll., Zaldivar, B., Pointon, B. W., Blaszczyk, F. d. M., Kearns, E., Raaf, J. L., Stone, J. L., Wan, L., Wester, T., Bian, J., Griskevich, N. J., Kropp, W. R., Locke, S., Mine, S., Smy, M. B., Sobel, H. W., Takhistov, V., Hill, J., Kim, J. Y., Lim, I. T., Park, R. G., Bodur, B., Scholberg, K., Walter, C. W., Bernard, L., Coffani, A., Drapier, O., Hedri, S. El, Giampaolo, A., Gonin, M., Mueller, Th. A., Paganini, P., Quilain, B., Ishizuka, T., Nakamura, T., Jang, J. S., Learned, J. G., Anthony, L. H. V., Martin, D., Scott, M., Sztuc, A. A., Uchida, Y., Cao, S., Berardi, V., Catanesi, M. G., Radicioni, E., Calabria, N. F., Machado, L. N., De Rosa, G., Collazuol, G., Iacob, F., Lamoureux, M., Mattiazzi, M., Ospina, N., Ludovici, L., Maekawa, Y., Nishimura, Y., Friend, M., Hasegawa, T., Ishida, T., Kobayashi, T., Jakkapu, M., Matsubara, T., Nakadaira, T., Nakamura, K., Oyama, Y., Sakashita, K., Sekiguchi, T., Tsukamoto, T., Boschi, T., Gao, J., Di Lodovico, F., Migenda, J., Taani, M., Zsoldos, S., Kotsar, Y., Nakano, Y., Ozaki, H., Shiozawa, T., Suzuki, A. T., Takeuchi, Y., Yamamoto, S., Ali, A., Ashida, Y., Feng, J., Hirota, S., Kikawa, T., Mori, M., Nakaya, T., Wendell, R. A., Yasutome, K., Fernandez, P., McCauley, N., Mehta, P., Tsui, K. M., Fukuda, Y., Itow, Y., Menjo, H., Niwa, T., Sato, K., Tsukada, M., Lagoda, J., Lakshmi, S. M., Mijakowski, P., Zalipska, J., Jiang, J., Jung, C. K., Vilela, C., Wilking, M. J., Yanagisawa, C., Hagiwara, K., Harada, M., Horai, T., Ishino, H., Ito, S., Kitagawa, F., Koshio, Y., Ma, W., Piplani, N., Sakai, S., Barr, G., Barrow, D., Cook, L., Goldsack, A., Samani, S., Wark, D., Nova, F., Yang, J. Y., Jenkins, S. J., Malek, M., McElwee, J. M., Stone, O., Thiesse, M. D., Thompson, L. F., Okazawa, H., Kim, S. B., Seo, J. W., Yu, I., Ichikawa, A. K., Nishijima, K., Koshiba, M., Iwamoto, K., Nakajima, Y., Ogawa, N., Yokoyama, M., Martens, K., Vagins, M. R., Kuze, M., Izumiyama, S., Yoshida, T., Inomoto, M., Ishitsuka, M., Ito, H., Kinoshita, T., Matsumoto, R., Ohta, K., Shinoki, M., Suganuma, T., Martin, J. F., Tanaka, H. A., Towstego, T., Akutsu, R., Hartz, M., Konaka, A., de Perio, P., Prouse, N. W., Chen, S., Xu, B. D., Posiadala-Zezula, M., Hadley, D., O'Flaherty, M., Richards, B., Jamieson, B., Walker, J., Minamino, A., Pintaudi, G., Sano, S., and Sasaki, R.
Subjects: Physics - Instrumentation and Detectors, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: In order to improve Super-Kamiokande's neutron detection efficiency and to thereby increase its sensitivity to the diffuse supernova neutrino background flux, 13 tons of $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$ (gadolinium sulfate octahydrate) was dissolved into the detector's otherwise ultrapure water from July 14 to August 17, 2020, marking the start of the SK-Gd phase of operations. During the loading, water was continuously recirculated at a rate of 60 m$^3$/h, extracting water from the top of the detector and mixing it with concentrated $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$ solution to create a 0.02% solution of the Gd compound before injecting it into the bottom of the detector. A clear boundary between the Gd-loaded and pure water was maintained through the loading, enabling monitoring of the loading itself and the spatial uniformity of the Gd concentration over the 35 days it took to reach the top of the detector. During the subsequent commissioning the recirculation rate was increased to 120 m$^3$/h, resulting in a constant and uniform distribution of Gd throughout the detector and water transparency equivalent to that of previous pure-water operation periods. Using an Am-Be neutron calibration source the mean neutron capture time was measured to be $115\pm1$ $\mu$s, which corresponds to a Gd concentration of $111\pm2$ ppm, as expected for this level of Gd loading. This paper describes changes made to the water circulation system for this detector upgrade, the Gd loading procedure, detector commissioning, and the first neutron calibration measurements in SK-Gd., Comment: 37 pages, 19 Figures, Accepted for publication in Nucl. Instrum. Meth. A
Published: 2021
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10. Search for neutrinos in coincidence with gravitational wave events from the LIGO-Virgo O3a Observing Run with the Super-Kamiokande detector

Author: collaboration, The Super-Kamiokande, Abe, K., Bronner, C., Hayato, Y., Ikeda, M., Imaizumi, S., Kameda, J., Kanemura, Y., Kataoka, Y., Miki, S., Miura, M., Moriyama, S., Nagao, Y., Nakahata, M., Nakayama, S., Okada, T., Okamoto, K., Orii, A., Pronost, G., Sekiya, H., Shiozawa, M., Sonoda, Y., Suzuki, Y., Takeda, A., Takemoto, Y., Takenaka, A., Tanaka, H., Watanabe, S., Yano, T., Han, S., Kajita, T., Okumura, K., Tashiro, T., Wang, R., Xia, J., Megias, G. D., Bravo-Berguño, D., Labarga, L., Marti, Ll., Zaldivar, B., Pointon, B. W., Blaszczyk, F. d. M., Kearns, E., Raaf, J. L., Stone, J. L., Wan, L., Wester, T., Bian, J., Griskevich, N. J., Kropp, W. R., Locke, S., Mine, S., Smy, M. B., Sobel, H. W., Takhistov, V., Weatherly, P., Hill, J., Kim, J. Y., Lim, I. T., Park, R. G., Bodur, B., Scholberg, K., Walter, C. W., Bernard, L., Coffani, A., Drapier, O., Hedri, S. El, Giampaolo, A., Gonin, M., Mueller, Th. A., Paganini, P., Quilain, B., Ishizuka, T., Nakamura, T., Jang, J. S., Learned, J. G., Anthony, L. H. V., Martin, D. G. R., Sztuc, A. A., Uchida, Y., Berardi, V., Catanesi, M. G., Radicioni, E., Calabria, N. F., Machado, L. N., De Rosa, G., Collazuol, G., Iacob, F., Lamoureux, M., Ospina, N., Ludovici, L., Maekawa, Y., Nishimura, Y., Cao, S., Friend, M., Hasegawa, T., Ishida, T., Jakkapu, M., Kobayashi, T., Matsubara, T., Nakadaira, T., Nakamura, K., Oyama, Y., Sakashita, K., Sekiguchi, T., Tsukamoto, T., Kotsar, Y., Nakano, Y., Ozaki, H., Shiozawa, T., Suzuki, A. T., Takeuchi, Y., Yamamoto, S., Ali, A., Ashida, Y., Feng, J., Hirota, S., Kikawa, T., Mori, M., Nakaya, T., Wendell, R. A., Yasutome, K., Fernandez, P., McCauley, N., Mehta, P., Pritchard, A., Tsui, K. M., Fukuda, Y., Itow, Y., Menjo, H., Niwa, T., Sato, K., Tsukada, M., Mijakowski, P., Jiang, J., Jung, C. K., Vilela, C., Wilking, M. J., Yanagisawa, C., Hagiwara, K., Harada, M., Horai, T., Ishino, H., Ito, S., Koshio, Y., Kitagawa, H., Ma, W., Piplani, N., Sakai, S., Kuno, Y., Barr, G., Barrow, D., Cook, L., Goldsack, A., Samani, S., Simpson, C., Wark, D., Nova, F., Boschi, T., Di Lodovico, F., Migenda, J., Sedgwick, S. Molina, Taani, M., Zsoldos, S., Yang, J. Y., Jenkins, S. J., Malek, M., McElwee, J. M., Stone, O., Thiesse, M. D., Thompson, L. F., Okazawa, H., Kim, S. B., Yu, I., Nishijima, K., Koshiba, M., Nakajima, K. Iwamoto Y., Ogawa, N., Yokoyama, M., Martens, K., Vagins, M. R., Izumiyama, S., Kuze, M., Tanaka, M., Yoshida, T., Inomoto, M., Ishitsuka, M., Ito, H., Matsumoto, R., Ohta, K., Shinoki, M., Martin, J. F., Tanaka, H. A., Towstego, T., Akutsu, R., Hartz, M., Konaka, A., de Perio, P., Prouse, N. W., Chen, S., Xu, B. D., Posiadala-Zezula, M., Hadley, D., Richards, B., Jamieson, B., Walker, J., Minamino, A., Pintaudi, G., Sano, S., Sasaki, R., Ichikawa, A. K., and Nakamura, K. D.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, High Energy Physics - Experiment
Abstract: The Super-Kamiokande detector can be used to search for neutrinos in time coincidence with gravitational waves detected by the LIGO-Virgo Collaboration (LVC). Both low-energy ($7-100$ MeV) and high-energy ($0.1-10^5$ GeV) samples were analyzed in order to cover a very wide neutrino spectrum. Follow-ups of 36 (out of 39) gravitational waves reported in the GWTC-2 catalog were examined; no significant excess above the background was observed, with 10 (24) observed neutrinos compared with 4.8 (25.0) expected events in the high-energy (low-energy) samples. A statistical approach was used to compute the significance of potential coincidences. For each observation, p-values were estimated using neutrino direction and LVC sky map ; the most significant event (GW190602_175927) is associated with a post-trial p-value of $7.8\%$ ($1.4\sigma$). Additionally, flux limits were computed independently for each sample and by combining the samples. The energy emitted as neutrinos by the identified gravitational wave sources was constrained, both for given flavors and for all-flavors assuming equipartition between the different flavors, independently for each trigger and by combining sources of the same nature., Comment: 16 pages, 5 figures. v2: adding corrections from The Astrophysical Journal review
Published: 2021
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11. Search for Tens of MeV Neutrinos associated with Gamma-Ray Bursts in Super-Kamiokande

Author: Collaboration, The Super-Kamiokande, Orii, A., Abe, K., Bronner, C., Hayato, Y., Ikeda, M., Imaizumi, S., Ito, H., Kameda, J., Kataoka, Y., Kato, Y., Kishimoto, Y., Miura, M., Moriyama, S., Mochizuki, T., Nagao, Y., Nakahata, M., Nakajima, Y., Nakayama, S., Okada, T., Okamoto, K., Pronost, G., Sekiya, H., Shiozawa, M., Sonoda, Y., Suzuki, Y., Takeda, A., Takemoto, Y., Takenaka, A., Tanaka, H., Yano, T., Han, S., Kajita, T., Okumura, K., Tashiro, T., Wang, R., Xia, J., Megias, G. D., Bravo-Berguno, D., Labarga, L., Marti, Ll., Zaldivar, B., Blaszczyk, F. d. M., Kearns, E., Raaf, J. L., Stone, J. L., Wan, L., Wester, T., Pointon, B. W., Bian, J., Griskevich, N. J., Kropp, W. R., Locke, S., Mine, S., Smy, M. B., Sobel, H. W., Takhistov, V., Weatherly, P., Ganezer, K. S., Hill, J., Kim, J. Y., Lim, I. T., Park, R. G., Bodur, B., Scholberg, K., Walter, C. W., Bernard, L., Coffani, A., Drapier, O., Hedri, S. El, Giampaolo, A., Gonin, M., Mueller, Th. A., Paganini, P., Quilain, B., Ishizuka, T., Nakamura, T., Jang, J. S., Learned, J. G., Matsuno, S., Anthony, L. H. V., Litchfield, R. P., Sztuc, A. A., Uchida, Y., Berardi, V., Catanesi, M. G., Radicioni, E., Calabria, N. F., Machado, L. N., De Rosa, G., Collazuol, G., Iacob, F., Lamoureux, M., Ospina, N., Ludovici, L., Nishimura, Y., Cao, S., Friend, M., Hasegawa, T., Ishida, T., Kobayashi, T., Jakkapu, M., Matsubara, T., Nakadaira, T., Nakamura, K., Oyama, Y., Sakashita, K., Sekiguchi, T., Tsukamoto, T., Boschi, T., Di Lodovico, F., Sedgwick, S. Molina, Taani, M., Zsoldos, S., Hasegawa, M., Isobe, Y., Miyabe, H., Nakano, Y., Shiozawa, T., Sugimoto, T., Suzuki, A. T., Takeuchi, Y., Yamamoto, S., Ali, A., Ashida, Y., Feng, J., Hirota, S., Jiang, M., Ichikawa, A. K., Kikawa, T., Mori, M., Nakamura, KE., Nakaya, T., Wendell, R. A., Yasutome, K., Fernandez, P., McCauley, N., Mehta, P., Pritchard, A., Tsui, K. M., Fukuda, Y., Itow, Y., Menjo, H., Niwa, T., Sato, K., Tsukada, M., Mijakowski, P., Frankiewicz, K., Jung, C. K., Vilela, C., Wilking, M. J., Yanagisawa, C., Fukuda, D., Harada, M., Hagiwara, K., Horai, T., Ishino, H., Ito, S., Koshio, Y., Ma, W., Piplani, N., Sakai, S., Sakuda, M., Takahira, Y., Xu, C., Kuno, Y., Barr, G., Barrow, D., Cook, L., Goldsack, A., Samani, S., Simpson, C., Wark, D., Nova, F., Yang, J. Y., Jenkins, S. J., Malek, M., McElwee, J. M., Stone, O., Thiesse, M. D., Thompson, L. F., Okazawa, H., Choi, Y., Kim, S. B., Yu, I., Nishijima, K., Koshiba, M., Iwamoto, K., Ogawa, N., Yokoyama, M., Martens, K., Vagins, M. R., Izumiyama, S., Kuze, M., Tanaka, M., Yoshida, T., Inomoto, M., Ishitsuka, M., Matsumoto, R., Ohta, K., Shinoki, M., Martin, J. F., Nantais, C. M., Tanaka, H. A., Towstego, T., Akutsu, R., Hartz, M., Konaka, A., de Perio, P., Prouse, N. W., Chen, S., Xu, B. D., Posiadala-Zezula, M., Richards, B., Jamieson, B., Walker, J., Minamino, A., Pintaudi, G., and Sasaki, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract: A search for neutrinos produced in coincidence with Gamma-Ray Bursts(GRB) was conducted with the Super-Kamiokande (SK) detector. Between December 2008 and March 2017, the Gamma-ray Coordinates Network recorded 2208 GRBs that occurred during normal SK operation. Several time windows around each GRB were used to search for coincident neutrino events. No statistically significant signal in excess of the estimated backgrounds was detected. The $\bar\nu_e$ fluence in the range from 8 MeV to 100 MeV in positron total energy for $\bar\nu_e+p\rightarrow e^{+}+n$ was found to be less than $\rm 5.07\times10^5$ cm$^{-2}$ per GRB in 90\% C.L. Upper bounds on the fluence as a function of neutrino energy were also obtained., Comment: 29 pages, 16 figures, 5 tables, accepted by PTEP
Published: 2021

12. Search for solar electron anti-neutrinos due to spin-flavor precession in the Sun with Super-Kamiokande-IV

Author: Collaboration, Super-Kamiokande, Abe, K., Bronner, C., Hayato, Y., Ikeda, M., Imaizumi, S., Ito, H., Kameda, J., Kataoka, Y., Miura, M., Moriyama, S., Nagao, Y., Nakahata, M., Nakajima, Y., Nakayama, S., Okada, T., Okamoto, K., Orii, A., Pronost, G., Sekiya, H., Shiozawa, M., Sonoda, Y., Suzuki, Y., Takeda, A., Takemoto, Y., Takenaka, A., Tanaka, H., Yano, T., Akutsu, R., Han, S., Kajita, T., Okumura, K., Tashiro, T., Wang, R., Xia, J., Bravo-Berguño, D., Labarga, L., Marti, Ll., Zaldivar, B., Blaszczyk, F. d. M., Kearns, E., Raaf, J. L., Stone, J. L., Wan, L., Wester, T., Pointin, B. W., Bian, J., Griskevich, N. J., Kropp, W. R., Locke, S., Mine, S., Smy, M. B., Sobel, H. W., Takhistov, V., Weatherly, P., Hill, J., Kim, J. Y., Lim, I. T., Park, R. G., Bodur, B., Scholberg, K., Walter, C. W., Bernard, L., Coffani, A., Drapier, O., Hedri, S. El, Giampaolo, A., Gonin, M., Mueller, Th. A., Paganini, P., Quilain, B., Ishizuka, T., Nakamura, T., Jang, J. S., Learned, J. G., Anthony, L. H. V., Sztuc, A. A., Uchida, Y., Berardi, V., Catanesi, M. G., Radicioni, E., Calabria, N. F., Machado, L. N., De Rosa, G., Collazuol, G., Iacob, F., Lamoureux, M., Ospina, N., Ludovici, L., Nishimura, Y., Cao, S., Friend, M., Hasegawa, T., Ishida, T., Jakkapu, M., Kobayashi, T., Matsubara, T., Nakadaira, T., Nakamura, K., Oyama, Y., Sakashita, K., Sekiguchi, T., Tsukamoto, T., Nakano, Y., Shiozawa, T., Suzuki, A. T., Takeuchi, Y., Yamamoto, S., Ali, A., Ashida, Y., Feng, J., Hirota, S., Ichikawa, A. K., Kikawa, T., Mori, M., Nakaya, T., Wendell, R. A., Yasutome, Y., Fernandez, P., McCauley, N., Mehta, P., Pritchard, A., Tsui, K. M., Fukuda, Y., Itow, Y., Menjo, H., Niwa, T., Sato, K., Tsukada, M., Mijakowski, P., Jung, C. K., Vilela, C., Wilking, M. J., Yanagisawa, C., Harada, M., Hagiwara, K., Horai, T., Ishino, H., Ito, S., Koshio, Y., Ma, W., Piplani, N., Sakai, S., Kuno, Y., Barr, G., Barrow, D., Cook, L., Goldsack, A., Samani, S., Simpson, C., Wark, D., Nova, F., Boschi, T., Di Lodovico, F., Taani, M., Migenda, J., Sedgwick, S. Molina, Zsoldos, S., Yang, J. Y., Jenkins, S. J., Malek, M., McElwee, J. M., Stone, O., Thiesse, M. D., Thompson, L. F., Okazawa, H., Kim, S. B., Yu, I., Nishijima, K., Koshiba, M., Iwamoto, K., Ogawa, N., Yokoyama, M., Martens, K., Vagins, M. R., Izumiyama, S., Kuze, M., Tanaka, M., Yoshida, T., Inomoto, M., Ishitsuka, M., Matsumoto, R., Ohta, K., Shinoki, M., Martin, J. F., Tanaka, H. A., Towstego, T., Hartz, M., Konaka, A., de Perio, P., Prouse, N. W., Chen, S., Xu, B. D., Richards, B., Jamieson, B., Walker, J., Minamino, A., Pintaudi, G., Sasaki, R., and Posiadala-Zezula, M.
Subjects: High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract: Due to a very low production rate of electron anti-neutrinos ($\bar{\nu}_e$) via nuclear fusion in the Sun, a flux of solar $\bar{\nu}_e$ is unexpected. An appearance of $\bar{\nu}_e$ in solar neutrino flux opens a new window for the new physics beyond the standard model. In particular, a spin-flavor precession process is expected to convert an electron neutrino into an electron anti-neutrino (${\nu_e\to\bar{\nu}_e}$) when neutrino has a finite magnetic moment. In this work, we have searched for solar $\bar{\nu}_e$ in the Super-Kamiokande experiment, using neutron tagging to identify their inverse beta decay signature. We identified 78 $\bar{\nu}_e$ candidates for neutrino energies of 9.3 to 17.3 MeV in 2970.1 live days with a fiducial volume of 22.5 kiloton water (183.0 kton$\cdot$year exposure). The energy spectrum has been consistent with background predictions and we thus derived a 90% confidence level upper limit of ${4.7\times10^{-4}}$ on the $\nu_e\to\bar{\nu}_e$ conversion probability in the Sun. We used this result to evaluate the sensitivity of future experiments, notably the Super-Kamiokande Gadolinium (SK-Gd) upgrade., Comment: 16 pages, 10 figures, 7 tables
Published: 2020
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13. Neutron-Antineutron Oscillation Search using a 0.37 Megaton$\cdot$Year Exposure of Super-Kamiokande

Author: Collaboration, Super-Kamiokande, Abe, K., Bronner, C., Hayato, Y., Ikeda, M., Imaizumi, S., Ito, H., Kameda, J., Kataoka, Y., Miura, M., Moriyama, S., Nagao, Y., Nakahata, M., Nakajima, Y., Nakayama, S., Okada, T., Okamoto, K., Orii, A., Pronost, G., Sekiya, H., Shiozawa, M., Sonoda, Y., Suzuki, Y., Takeda, A., Takemoto, Y., Takenaka, A., Tanaka, H., Yano, T., Akutsu, R., Han, S., Kajita, T., Okumura, K., Tashiro, T., Wang, R., Xia, J., Bravo-Berguño, D., Labarga, L., Marti, Ll., Zaldivar, B., Blaszczyk, F. d. M., Kearns, E., Gustafson, J. D., Raaf, J. L., Stone, J. L., Wan, L., Wester, T., Bian, J., Griskevich, N. J., Kropp, W. R., Locke, S., Mine, S., Smy, M. B., Sobel, H. W., Takhistov, V., Weatherly, P., Hill, J., Kim, J. Y., Lim, I. T., Park, R. G., Bodur, B., Scholberg, K., Walter, C. W., Coffani, A., Drapier, O., Hedri, S. El, Giampaolo, A., Gonin, M., Mueller, Th. A., Paganini, P., Quilain, B., Ishizuka, T., Nakamura, T., Jang, J. S., Learned, J. G., Anthony, L. H. V., Sztuc, A. A., Uchida, Y., Berardi, V., Catanesi, M. G., Radicioni, E., Calabria, N. F., Machado, L. N., De Rosa, G., Collazuol, G., Iacob, F., Lamoureux, M., Ospina, N., Ludovici, L., Nishimura, Y., Cao, S., Friend, M., Hasegawa, T., Ishida, T., Kobayashi, T., Matsubara, T., Nakadaira, T., Jakkapu, M., Nakamura, K., Oyama, Y., Sakashita, K., Sekiguchi, T., Tsukamoto, T., Nakano, Y., Shiozawa, T., Suzuki, A. T., Takeuchi, Y., Yamamoto, S., Ali, A., Ashida, Y., Feng, J., Hirota, S., Ichikawa, A. K., Kikawa, T., Mori, M., Nakaya, T., Wendell, R. A., Yasutome, K., Fernandez, P., McCauley, N., Mehta, P., Pritchard, A., Tsui, K. M., Fukuda, Y., Itow, Y., Menjo, H., Niwa, T., Sato, K., Tsukada, M., Mijakowski, P., Posiadala-Zezula, M., Jung, C. K., Vilela, C., Wilking, M. J., Yanagisawa, C., Harada, M., Hagiwara, K., Horai, T., Ishino, H., Ito, S., Koshio, Y., Ma, W., Piplani, N., Sakai, S., Kuno, Y., Barr, G., Barrow, D., Cook, L., Goldsack, A., Samani, S., Simpson, C., Wark, D., Nova, F., Boschi, T., Di Lodovico, F., Sedgwick, S. Molina, Taani, M., Zsoldos, S., Yang, J. Y., Jenkins, S. J., McElwee, J. M., Thiesse, M. D., Thompson, L. F., Malek, M., Stone, O., Okazawa, H., Kim, S. B., Yu, I., Nishijima, K., Koshiba, M., Ogawa, N., Iwamoto, K., Yokoyama, M., Martens, K., Vagins, M. R., Kuze, M., Izumiyama, S., Tanaka, M., Yoshida, T., Inomoto, M., Ishitsuka, M., Matsumoto, R., Ohta, K., Shinoki, M., Martin, J. F., Tanaka, H. A., Towstego, T., Hartz, M., Konaka, A., de Perio, P., Prouse, N. W., Pointon, B. W., Chen, S., Xu, B. D., Richards, B., Jamieson, B., Walker, J., Minamino, A., Pintaudi, G., and Sasaki, R.
Subjects: High Energy Physics - Experiment
Abstract: 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..
Published: 2020
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14. Search for proton decay via $p\to e^+\pi^0$ and $p\to \mu^+\pi^0$ with an enlarged fiducial volume in Super-Kamiokande I-IV

Author: Collaboration, Super-Kamiokande, Takenaka, A., Abe, K., Bronner, C., Hayato, Y., Ikeda, M., Imaizumi, S., Ito, H., Kameda, J., Kataoka, Y., Kato, Y., Kishimoto, Y., Marti, Ll., Miura, M., Moriyama, S., Mochizuki, T., Nagao, Y., Nakahata, M., Nakajima, Y., Nakayama, S., Okada, T., Okamoto, K., Orii, A., Pronost, G., Sekiya, H., Shiozawa, M., Sonoda, Y., Suzuki, Y., Takeda, A., Takemoto, Y., Tanaka, H., Yano, T., Akutsu, R., Han, S., Kajita, T., Okumura, K., Tashiro, T., Wang, R., Xia, J., Bravo-Berguno, D., Labarga, L., Fernandez, P., Zaldivar, B., Blaszczyk, F. d. M., Kearns, E., Raaf, J. L., Stone, J. L., Wan, L., Wester, T., Pointon, B. W., Bian, J., Griskevich, N. J., Kropp, W. R., Locke, S., Mine, S., Smy, M. B., Sobel, H. W., Takhistov, V., Weatherly, P., Ganezer, K. S., Hill, J., Kim, J. Y., Lim, I. T., Park, R. G., Bodur, B., Scholberg, K., Walter, C. W., Coffani, A., Drapier, O., Hedri, S. El, Giampaolo, A., Gonin, M., Mueller, Th. A., Paganini, P., Quilain, B., Ishizuka, T., Nakamura, T., Jang, J. S., Learned, J. G., Matsuno, S., Anthony, L. H. V., Litchfield, R. P., Sztuc, A. A., Uchida, Y., Berardi, V., Catanesi, M. G., Radicioni, E., Calabria, N. F., Machado, L. N., De Rosa, G., Collazuol, G., Iacob, F., Lamoureux, M., Ospina, N., Ludovici, L., Nishimura, Y., Cao, S., Friend, M., Hasegawa, T., Ishida, T., Jakkapu, M., Kobayashi, T., Matsubara, T., Nakadaira, T., Nakamura, K., Oyama, Y., Sakashita, K., Sekiguchi, T., Tsukamoto, T., Hasegawa, M., Isobe, Y., Miyabe, H., Nakano, Y., Shiozawa, T., Sugimoto, T., Suzuki, A. T., Takeuchi, Y., Yamamoto, S., Ali, A., Ashida, Y., Feng, J., Hirota, S., Ichikawa, A. K., Jiang, M., Kikawa, T., Mori, M., Nakamura, KE., Nakaya, T., Wendell, R. A., Yasutome, K., McCauley, N., Mehta, P., Pritchard, A., Tsui, K. M., Fukuda, Y., Itow, Y., Menjo, H., Niwa, T., Sato, K., Taani, M., Tsukada, M., Mijakowski, P., Frankiewicz, K., Jung, C. K., Santucci, G., Vilela, C., Wilking, M. J., Yanagisawa, C., Fukuda, D., Harada, M., Hagiwara, K., Horai, T., Ishino, H., Ito, S., Koshio, Y., Ma, W., Piplani, N., Sakai, S., Sakuda, M., Takahira, Y., Xu, C., Kuno, Y., Barr, G., Barrow, D., Cook, L., Simpson, C., Wark, D., Nova, F., Boschi, T., Di Lodovico, F., Sedgwick, S. Molina, Zsoldos, S., Yang, J. Y., Jenkins, S. J., McElwee, J. M., Thiesse, M. D., Thompson, L. F., Okazawa, H., Choi, Y., Kim, S. B., Yu, I., Nishijima, K., Koshiba, M., Iwamoto, K., Ogawa, N., Yokoyama, M., Goldsack, A., Martens, K., Vagins, M. R., Kuze, M., Tanaka, M., Yoshida, T., Inomoto, M., Ishitsuka, M., Matsumoto, R., Ohta, K., Shinoki, M., Martin, J. F., Nantais, C. M., Tanaka, H. A., Towstego, T., Hartz, M., Konaka, A., de Perio, P., Prouse, N. W., Chen, S., Xu, B. D., Posiadala-Zezula, M., Richards, B., Jamieson, B., Walker, J., Minamino, A., Pintaudi, G., and Sasaki, R.
Subjects: High Energy Physics - Experiment
Abstract: We have searched for proton decay via $p\to e^+\pi^0$ and $p\to \mu^+\pi^0$ modes with the enlarged fiducial volume data of Super-Kamiokande from April 1996 to May 2018, which corresponds to 450 kton$\cdot$years exposure. We have accumulated about 25% more livetime and enlarged the fiducial volume of the Super-Kamiokande detector from 22.5 kton to 27.2 kton for this analysis, so that 144 kton$\cdot$years of data, including 78 kton$\cdot$years of additional fiducial volume data, has been newly analyzed. No candidates have been found for $p\to e^+\pi^0$ and one candidate remains for $p\to \mu^+\pi^0$ in the conventional 22.5 kton fiducial volume and it is consistent with the atmospheric neutrino background prediction. We set lower limits on the partial lifetime for each of these modes: $\tau/B(p\to e^+\pi^0) > 2.4 \times 10^{34}$ years and $\tau/B(p\to \mu^+\pi^0) > 1.6 \times 10^{34}$ years at 90% confidence level., Comment: 16 pages, 10 figures
Published: 2020
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15. Magnetization control by angular momentum transfer from surface acoustic wave to ferromagnetic spin moments

Author: Sasaki, R., Nii, Y., and Onose, Y.
Subjects: Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract: The angular momentum interconversion between electron spin and other type of angular momenta is useful to develop new spintronic functionalities. The conversions from the angular momentum of photon and mechanical rotation to ferromagnetic spin moment have been well studied. While the recent studies theoretically suggested circular vibration of atoms works as angular momentum of phonon, the direct experimental demonstration of conversion to spin moments remains to be performed. Here we demonstrate that the phonon angular momentum of surface acoustic wave can control the magnetization of a ferromagnetic Ni film by means of the phononic-to-electronic conversion of angular momentum in Ni/LiNbO$_3$ hybrid device. This result clearly shows the phonon angular momentum is useful to further fictionalize spintronic devices.
Published: 2020
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16. Surface acoustic wave coupled to magnetic resonance on a multiferroic CuB$_2$O$_4$

Author: Sasaki, R., Nii, Y., and Onose, Y.
Subjects: Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract: We observed surface acoustic wave (SAW) propagation on a multiferroic material CuB$_2$O$_4$ with use of two interdigital transducers (IDTs). The period of IDT fingers is as short as 1.6 $\mu$m so that the frequency of SAW is 3 GHz, which is comparable with that of magnetic resonance. In antiferromagnetic phase, the SAW excitation intensity varied with the magnitude and direction of the magnetic field, owing to the dynamical coupling between SAWs and antiferromagnetic resonance of CuB$_2$O$_4$. The microscopic mechanism is discussed based on the symmetrically allowed magentoelastic coupling.
Published: 2018
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17. Microwave Magneto-Chiral Effect in a Noncentro-symmetric Magnet CuB2O4

Author: Nii, Y., Sasaki, R., Iguchi, Y., and Onose, Y.
Subjects: Condensed Matter - Materials Science
Abstract: We have investigated microwave nonreciprocity in a noncentro-symmetric magnet CuB2O4. We simultaneously observed differently originated nonreciprocities; the classical magnetic dipolar effect and the magneto-chiral (MCh) effect. By rotating magnetic field in a tetragonal plane, we clearly unveil qualitative difference between them. The MCh effect signal reveals chiral transitions from one enantiomer to the other via intermediate achiral state. We show magnetoelectric effect plays an essential role for the emergence of microwave MCh effect., Comment: 12 pages, 7 figures
Published: 2016
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18. Nonreciprocal propagation of surface acoustic wave in Ni/LiNbO3

Author: Sasaki, R., Nii, Y., Iguchi, Y., and Onose, Y.
Subjects: Condensed Matter - Materials Science
Abstract: We have investigated surface acoustic wave propagation in Ni/LiNbO$_3$ hybrid devices. We have found the absorption and phase velocity are dependent on the sign of wave vector in a device, which indicates the nonreciprocal propagation characteristic of systems with time reversal and spatial inversion simultaneously broken symmetries. The nonreciprocity is reversed by the 180$^\circ$ rotation of magnetic field. Nonreciprocity seems largely dependent on the shape of ferromagnetic Ni film. The origin of these observations is ascribed to film shape dependent magnetoelastic coupling., Comment: 12 pages, 6 figures
Published: 2016
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19. Weight Gain After 20 Years of Age is Associated with Unfavorable Lifestyle and Increased Prevalence of Metabolic Disorders

Author: Takebe N, Tanno K, Ohmomo H, Hangai M, Oda T, Hasegawa Y, Takanashi N, Sasaki R, Shimizu A, Sasaki A, Sakata K, Sasaki M, and Ishigaki Y
Subjects: metabolic syndrome, physical activity, skipping breakfast, sleep duration, waist circumference, weight gain., Specialties of internal medicine, RC581-951
Abstract: Noriko Takebe,1,2 Kozo Tanno,2,3 Hideki Ohmomo,2 Mari Hangai,1,2 Tomoyasu Oda,1 Yutaka Hasegawa,1,2 Nobuyuki Takanashi,2,3 Ryohei Sasaki,2,4 Atsushi Shimizu,2 Akira Sasaki,5 Kiyomi Sakata,2,3 Makoto Sasaki,2 Yasushi Ishigaki1,2 1Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Iwate Medical University, Yahaba, Japan; 2Iwate Tohoku Medical Megabank Organization, Iwate Medical University, Yahaba, Japan; 3Department of Hygiene and Preventive Medicine, Iwate Medical University, Yahaba, Japan; 4Department of Human Sciences, Center for Liberal Arts and Sciences, Iwate Medical University, Yahaba, Japan; 5Department of Surgery, Iwate Medical University, Yahaba, JapanCorrespondence: Yasushi IshigakiDivision of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Iwate Medical University, 2-1-1 Idai-Dori, Yahaba, Iwate, 028-3695, JapanTel +81 19 613 7111Fax +81 19 907 8270Email ishigaki@iwate-med.ac.jpPurpose: It is unclear what kind of modifiable lifestyle factors are associated with long-time weight gain in adulthood. To clarify the lifestyle behavior related to body weight gain since the age of 20 years, we explored the lifestyle risk factor, independently associated with excessive weight gain after 20 years of age as compared to those in subjects with a stable weight, with matching of age, gender, and the current body mass index (BMI).Patients and Methods: From baseline data of a general population-based cohort study, we designed a cross-sectional analysis collecting individual data of medical health check-ups and a questionnaire related to lifestyle, including amount of sleep, frequency of eating breakfast, average times per day engaged in walking and sitting in the prior year, and smoking habits. These data were compared between the subjects with weight gain ≥ 10kg (n=3601) and < 10kg (n=3601) after age 20, matched by a propensity score model which included current BMI, age and gender. We used multivariable logistic regressions to assess the lifestyle factor’s association with high weight gain.Results: Participants who gained ≥ 10 kg were significantly more likely to sleep < 5 hours or ≥ 9 hours per night, skip breakfast, engage in walking < 1 hour per day, and sit ≥ 5 hours per day than those who gained < 10kg. Multivariable logistic regressions analyses showed that, with adjusting for potential confounder, the lifestyles with the positive association with high weight gain were skipping breakfast (OR 1.252; 95% CI 1.053– 1.489, vs regularly), long sleeping duration (9 hours/day≤ OR 1.613; 95% CI 1.018– 2.557 vs 5≤-< 7 hours/day), and former smoker (OR 1.163; 95% CI 1.008– 1.343 vs never smoker), while walking duration was negatively associated with high weight gain. Furthermore, despite similar current BMI, participants with weight gain ≥ 10kg had significantly higher values for waist circumference, blood pressure, HbA1c, LDL-C, triglycerides, and hepatic enzyme levels than those with weight gain < 10kg. Similarly, the prevalence rates of hypertension, dyslipidemia, metabolic syndrome (MetS), and former smoker were higher in the participants with weight gain ≥ 10kg.Conclusion: Major weight gain after 20 years of age was associated with unfavorable lifestyle factors and greater waist circumference, possibly leading to elevated risk for MetS and other non-communicable diseases. These findings highlight the importance of maintaining both weight at age 20 and a favorable lifestyle throughout adulthood.Keywords: metabolic syndrome, physical activity, skipping breakfast, sleep duration, waist circumference, weight gain
Published: 2021

20. Extensions of a class of similarity solutions of Fokker-Planck equation with time-dependent coefficients and fixed/moving boundaries

Author: Ho, C. -L. and Sasaki, R.
Subjects: Mathematical Physics, Condensed Matter - Statistical Mechanics, Mathematics - Analysis of PDEs, Nonlinear Sciences - Exactly Solvable and Integrable Systems, Quantum Physics
Abstract: A general formula in closed form to obtain exact similarity solutions of the Fokker-Planck equation with both time-dependent drift and diffusion coefficients was recently presented by Lin and Ho [ Ann. Phys. \textbf{327}, 386 (2012); J. Math. Phys. \textbf{54}, 041501 (2013)]. In this paper we extend the class of exact solutions by exploiting certain properties of the general formula., Comment: 7 pages, no figures. arXiv admin note: text overlap with arXiv:1205.0763
Published: 2014

21. Magnetization control by angular momentum transfer from surface acoustic wave to ferromagnetic spin moments

Author: Sasaki, R., Nii, Y., and Onose, Y.
Published: 2021
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22. Scattering Amplitudes for Multi-indexed Extensions of Solvable Potentials

Author: Ho, C. -L., Lee, J. -C., and Sasaki, R.
Subjects: Quantum Physics, High Energy Physics - Theory, Mathematical Physics, Mathematics - Spectral Theory, Nonlinear Sciences - Exactly Solvable and Integrable Systems
Abstract: New solvable one-dimensional quantum mechanical scattering problems are presented. They are obtained from known solvable potentials by multiple Darboux transformations in terms of virtual and pseudo virtual wavefunctions. The same method applied to confining potentials, e.g. P\"oschl-Teller and the radial oscillator potentials, has generated the {\em multi-indexed Jacobi and Laguerre polynomials}. Simple multi-indexed formulas are derived for the transmission and reflection amplitudes of several solvable potentials., Comment: 28 pages, no figures. Acknowledgments revised
Published: 2013
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23. Confluence of apparent singularities in multi-indexed orthogonal polynomials: the Jacobi case

Author: Ho, C. -L., Sasaki, R., and Takemura, K.
Subjects: Mathematics - Classical Analysis and ODEs, High Energy Physics - Theory, Mathematical Physics, Nonlinear Sciences - Exactly Solvable and Integrable Systems, Quantum Physics
Abstract: The multi-indexed Jacobi polynomials are the main part of the eigenfunctions of exactly solvable quantum mechanical systems obtained by certain deformations of the P\"oschl-Teller potential (Odake-Sasaki). By fine-tuning the parameter(s) of the P\"oschl-Teller potential, we obtain several families of explicit and global solutions of certain second order Fuchsian differential equations with an apparent singularity of characteristic exponent -2 and -1. They form orthogonal polynomials over $x\in(-1,1)$ with weight functions of the form $(1-x)^\alpha(1+x)^\beta/\{(ax+b)^4q(x)^2\}$, in which $q(x)$ is a polynomial in $x$., Comment: 27 pages, no figures. A Table added to summarize the main results, typos corrected, some statements added to improve presentation. Version in J. Phys. A
Published: 2012
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24. Zeros of the exceptional Laguerre and Jacobi polynomials

Author: Ho, C. -L. and Sasaki, R.
Subjects: Mathematical Physics, High Energy Physics - Theory, Mathematics - Classical Analysis and ODEs, Nonlinear Sciences - Exactly Solvable and Integrable Systems, Quantum Physics
Abstract: An interesting discovery in the last two years in the field of mathematical physics has been the exceptional $X_\ell$ Laguerre and Jacobi polynomials. Unlike the well-known classical orthogonal polynomials which start with constant terms, these new polynomials have the lowest degree $\ell=1,2,...$, and yet they form complete sets with respect to some positive-definite measure. In this paper, we study one important aspect of these new polynomials, namely, the behaviors of their zeros as some parameters of the Hamiltonians change., Comment: 25 pages, 10 figures
Published: 2011

25. Calogero-Sutherland-Moser Systems, Ruijsenaars-Schneider-van Diejen Systems and Orthogonal Polynomials

Author: Odake, S. and Sasaki, R.
Subjects: High Energy Physics - Theory, Mathematical Physics
Abstract: The equilibrium positions of the multi-particle classical Calogero-Sutherland-Moser (CSM) systems with rational/trigonometric potentials associated with the classical root systems are described by the classical orthogonal polynomials; the Hermite, Laguerre and Jacobi polynomials. The eigenfunctions of the corresponding single-particle quantum CSM systems are also expressed in terms of the same orthogonal polynomials. We show that this interesting property is inherited by the Ruijsenaars-Schneider-van Diejen (RSvD) systems, which are integrable deformation of the CSM systems; the equilibrium positions of the multi-particle classical RSvD systems and the eigenfunctions of the corresponding single-particle quantum RSvD systems are described by the same orthogonal polynomials, the continuous Hahn (special case), Wilson and Askey-Wilson polynomials. They belong to the Askey-scheme of the basic hypergeometric orthogonal polynomials and are deformation of the Hermite, Laguerre and Jacobi polynomials, respectively. The Hamiltonians of these single-particle quantum mechanical systems have two remarkable properties, factorization and shape invariance., Comment: 16 pages, 1 figure
Published: 2005
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26. Explicit solutions of the classical Calogero & Sutherland systems for any root system

Author: Sasaki, R. and Takasaki, K.
Subjects: High Energy Physics - Theory, Mathematical Physics, Mathematics - Quantum Algebra, Nonlinear Sciences - Exactly Solvable and Integrable Systems
Abstract: Explicit solutions of the classical Calogero (rational with/without harmonic confining potential) and Sutherland (trigonometric potential) systems is obtained by diagonalisation of certain matrices of simple time evolution. The method works for Calogero & Sutherland systems based on any root system. It generalises the well-known results by Olshanetsky and Perelomov for the A type root systems. Explicit solutions of the (rational and trigonometric) higher Hamiltonian flows of the integrable hierarchy can be readily obtained in a similar way for those based on the classical root systems., Comment: 18 pages, LaTeX, no figure
Published: 2005
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27. Equilibrium Positions and Eigenfunctions of Shape Invariant (`Discrete') Quantum Mechanics

Author: Odake, S. and Sasaki, R.
Subjects: High Energy Physics - Theory, Mathematical Physics, Nonlinear Sciences - Exactly Solvable and Integrable Systems
Abstract: Certain aspects of the integrability/solvability of the Calogero-Sutherland-Moser systems and the Ruijsenaars-Schneider-van Diejen systems with rational and trigonometric potentials are reviewed. The equilibrium positions of classical multi-particle systems and the eigenfunctions of single-particle quantum mechanics are described by the same orthogonal polynomials: the Hermite, Laguerre, Jacobi, continuous Hahn, Wilson and Askey-Wilson polynomials. The Hamiltonians of these single-particle quantum mechanical systems have two remarkable properties, factorization and shape invariance., Comment: 30 pages, 1 figure. Contribution to proceedings of RIMS workshop "Elliptic Integrable Systems" (RIMS, Nov. 2004)
Published: 2005

28. Equilibrium Positions, Shape Invariance and Askey-Wilson Polynomials

Author: Odake, S. and Sasaki, R.
Subjects: High Energy Physics - Theory, Mathematical Physics, Nonlinear Sciences - Exactly Solvable and Integrable Systems
Abstract: We show that the equilibrium positions of the Ruijsenaars-Schneider-van Diejen systems with the trigonometric potential are given by the zeros of the Askey-Wilson polynomials with five parameters. The corresponding single particle quantum version, which is a typical example of "discrete" quantum mechanical systems with a q-shift type kinetic term, is shape invariant and the eigenfunctions are the Askey-Wilson polynomials. This is an extension of our previous study [1,2], which established the "discrete analogue" of the well-known fact; The equilibrium positions of the Calogero systems are described by the Hermite and Laguerre polynomials, whereas the corresponding single particle quantum versions are shape invariant and the eigenfunctions are the Hermite and Laguerre polynomials., Comment: 14 pages, 1 figure. The outline of derivation of the result in section 2 is added
Published: 2004
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29. Shape Invariant Potentials in 'Discrete Quantum Mechanics'

Author: Odake, S. and Sasaki, R.
Subjects: High Energy Physics - Theory, Mathematical Physics, Nonlinear Sciences - Exactly Solvable and Integrable Systems
Abstract: Shape invariance is an important ingredient of many exactly solvable quantum mechanics. Several examples of shape invariant ``discrete quantum mechanical systems" are introduced and discussed in some detail. They arise in the problem of describing the equilibrium positions of Ruijsenaars-Schneider type systems, which are "discrete" counterparts of Calogero and Sutherland systems, the celebrated exactly solvable multi-particle dynamics. Deformed Hermite and Laguerre polynomials are the typical examples of the eigenfunctions of the above shape invariant discrete quantum mechanical systems., Comment: 15 pages, 1 figure. Contribution to a special issue of Journal of Nonlinear Mathematical Physics in honour of Francesco Calogero on the occasion of his seventieth birthday
Published: 2004
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30. $Z_n$ elliptic Gaudin model with open boundaries

Author: Yang, W. -L., Sasaki, R., and Zhang, Y. -Z.
Subjects: High Energy Physics - Theory
Abstract: The $Z_n$ elliptic Gaudin model with integrable boundaries specified by generic non-diagonal K-matrices with $n+1$ free boundary parameters is studied. The commuting families of Gaudin operators are diagonalized by the algebraic Bethe ansatz method. The eigenvalues and the corresponding Bethe ansatz equations are obtained., Comment: 21 pages, Latex file
Published: 2004
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31. Polynomials Associated with Equilibria of Affine Toda-Sutherland Systems

Author: Odake, S. and Sasaki, R.
Subjects: High Energy Physics - Theory
Abstract: An affine Toda-Sutherland system is a quasi-exactly solvable multi-particle dynamics based on an affine simple root system. It is a `cross' between two well-known integrable multi-particle dynamics, an affine Toda molecule and a Sutherland system. Polynomials describing the equilibrium positions of affine Toda-Sutherland systems are determined for all affine simple root systems., Comment: 9 pages
Published: 2004
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32. Equilibria of `Discrete' Integrable Systems and Deformations of Classical Orthogonal Polynomials

Author: Odake, S. and Sasaki, R.
Subjects: High Energy Physics - Theory, Mathematics - Quantum Algebra
Abstract: The Ruijsenaars-Schneider systems are `discrete' version of the Calogero-Moser (C-M) systems in the sense that the momentum operator p appears in the Hamiltonians as a polynomial in e^{\pm\beta' p} (\beta' is a deformation parameter) instead of an ordinary polynomial in p in the hierarchies of C-M systems. We determine the polynomials describing the equilibrium positions of the rational and trigonometric Ruijsenaars-Schneider systems based on classical root systems. These are deformation of the classical orthogonal polynomials, the Hermite, Laguerre and Jacobi polynomials which describe the equilibrium positions of the corresponding Calogero and Sutherland systems. The orthogonality of the original polynomials is inherited by the deformed ones which satisfy three-term recurrence and certain functional equations. The latter reduce to the celebrated second order differential equations satisfied by the classical orthogonal polynomials., Comment: 45 pages. A few typos in section 6 are corrected
Published: 2004
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33. Central elements of the elliptic $Z_n$ monodromy matrix algebra at roots of unity

Author: Yang, W. -L., Belavin, A., and Sasaki, R.
Subjects: High Energy Physics - Theory, Mathematics - Quantum Algebra
Abstract: The central elements of the algebra of monodromy matrices associated with the $\mathbb{Z}_n$ R-matrix are studied. When the crossing parameter $w$ takes a special rational value $w=\frac{n}{N}$, where $N$ and $n$ are positive coprime integers, the center is substantially larger than that in the generic case for which the "quantum determinant" provides the center. In the trigonometric limit, the situation corresponds to the quantum group at roots of unity. This is a higher rank generalization of the recent results by Belavin and Jimbo., Comment: Latex file, 18 pages; V2: minor typos corrected and a reference updated
Published: 2004
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34. Affine Toda-Sutherland Systems

Author: Khare, Avinash, Loris, I., and Sasaki, R.
Subjects: High Energy Physics - Theory, Condensed Matter, Mathematical Physics, Nonlinear Sciences - Exactly Solvable and Integrable Systems, Quantum Physics
Abstract: A cross between two well-known integrable multi-particle dynamics, an affine Toda molecule and a Sutherland system, is introduced for any affine root system. Though it is not completely integrable but partially integrable, or quasi exactly solvable, it inherits many remarkable properties from the parents. The equilibrium position is algebraic, i.e. proportional to the Weyl vector. The frequencies of small oscillations near equilibrium are proportional to the affine Toda masses, which are essential ingredients of the exact factorisable S-matrices of affine Toda field theories. Some lower lying frequencies are integer times a coupling constant for which the corresponding exact quantum eigenvalues and eigenfunctions are obtained. An affine Toda-Calogero system, with a corresponding rational potential, is also discussed., Comment: LaTeX2e 22 pages with amsfonts and graphicx, 5 eps figures
Published: 2003
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35. Exact solution of $Z_n$ Belavin model with open boundary condition

Author: Yang, W. -L. and Sasaki, R.
Subjects: High Energy Physics - Theory, Nonlinear Sciences - Exactly Solvable and Integrable Systems
Abstract: $Z_n$ Belavin model with open boundary condition is studied. The double-row transfer matrices of the model are diagonalized by algebraic Bethe ansatz method in terms of the intertwiner and the face-vertex correspondence relation. The eigenvalues and the corresponding Bethe ansatz equations are obtained., Comment: Latex file, 28 pages
Published: 2003
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36. Solution of the dual reflection equation for $A^{(1)}_{n-1}$ SOS model

Author: Yang, W. -L. and Sasaki, R.
Subjects: High Energy Physics - Theory
Abstract: We obtain a diagonal solution of the dual reflection equation for elliptic $A^{(1)}_{n-1}$ SOS model. The isomorphism between the solutions of the reflection equation and its dual is studied., Comment: Latex file 12 pages, added references
Published: 2003
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37. Classical vs Quantum Mechanics: role of elementary excitations

Author: Loris, I. and Sasaki, R.
Subjects: Quantum Physics
Abstract: Simple theorems relating a quantum mechanical system to the corresponding classical one at equilibrium and connecting the quantum eigenvalues to the frequencies of normal modes oscillations are presented. Corresponding to each quantum eigenfunction, a ` classical eigenfunction' is associated. Those belonging to `elementary excitations' play an important role., Comment: LaTeX2e with amsfonts, 9 pages, no figures. Typos corrected. Three references added. Section 3 with summary and comments added
Published: 2003
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38. Quantum & Classical Eigenfunctions in Calogero & Sutherland Systems

Author: Loris, I. and Sasaki, R.
Subjects: High Energy Physics - Theory, Condensed Matter, Mathematical Physics, Nonlinear Sciences - Exactly Solvable and Integrable Systems, Quantum Physics
Abstract: An interesting observation was reported by Corrigan-Sasaki that all the frequencies of small oscillations around equilibrium are " quantised" for Calogero and Sutherland (C-S) systems, typical integrable multi-particle dynamics. We present an analytic proof by applying recent results of Loris-Sasaki. Explicit forms of `classical' and quantum eigenfunctions are presented for C-S systems based on any root systems., Comment: LaTeX2e 37 pages, references added, typo corrected, a few paragraphs added
Published: 2003
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39. Quantum vs Classical Integrability in Ruijsenaars-Schneider Systems

Author: Ragnisco, O. and Sasaki, R.
Subjects: High Energy Physics - Theory, Mathematical Physics, Mathematics - Quantum Algebra, Nonlinear Sciences - Exactly Solvable and Integrable Systems
Abstract: The relationship (resemblance and/or contrast) between quantum and classical integrability in Ruijsenaars-Schneider systems, which are one parameter deformation of Calogero-Moser systems, is addressed. Many remarkable properties of classical Calogero and Sutherland systems (based on any root system) at equilibrium are reported in a previous paper (Corrigan-Sasaki). For example, the minimum energies, frequencies of small oscillations and the eigenvalues of Lax pair matrices at equilibrium are all "integer valued". In this paper we report that similar features and results hold for the Ruijsenaars-Schneider type of integrable systems based on the classical root systems., Comment: LaTeX2e with amsfonts 15 pages, no figures
Published: 2003
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40. Polynomials Associated with Equilibrium Positions in Calogero-Moser Systems

Author: Odake, S. and Sasaki, R.
Subjects: High Energy Physics - Theory, Condensed Matter, Mathematical Physics
Abstract: In a previous paper (Corrigan-Sasaki), many remarkable properties of classical Calogero and Sutherland systems at equilibrium are reported. For example, the minimum energies, frequencies of small oscillations and the eigenvalues of Lax pair matrices at equilibrium are all "integer valued". The equilibrium positions of Calogero and Sutherland systems for the classical root systems (A_r, B_r, C_r and D_r) correspond to the zeros of Hermite, Laguerre, Jacobi and Chebyshev polynomials. Here we define and derive the corresponding polynomials for the exceptional (E_6, E_7, E_8, F_4 and G_2) and non-crystallographic (I_2(m), H_3 and H_4) root systems. They do not have orthogonality but share many other properties with the above mentioned classical polynomials., Comment: 41 pages. A Mathematica file "poly.m" is attached
Published: 2002
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41. Quantum vs Classical Integrability in Calogero-Moser Systems

Author: Corrigan, E. and Sasaki, R.
Subjects: High Energy Physics - Theory, Condensed Matter, Mathematical Physics, Nonlinear Sciences - Exactly Solvable and Integrable Systems, Quantum Physics
Abstract: Calogero-Moser systems are classical and quantum integrable multi-particle dynamics defined for any root system $\Delta$. The {\em quantum} Calogero systems having $1/q^2$ potential and a confining $q^2$ potential and the Sutherland systems with $1/\sin^2q$ potentials have "integer" energy spectra characterised by the root system $\Delta$. Various quantities of the corresponding {\em classical} systems, {\em e.g.} minimum energy, frequencies of small oscillations, the eigenvalues of the classical Lax pair matrices, etc. at the equilibrium point of the potential are investigated analytically as well as numerically for all root systems. To our surprise, most of these classical data are also "integers", or they appear to be "quantised". To be more precise, these quantities are polynomials of the coupling constant(s) with integer coefficients. The close relationship between quantum and classical integrability in Calogero-Moser systems deserves fuller analytical treatment, which would lead to better understanding of these systems and of integrable systems in general., Comment: LaTeX2e with amsfonts, 63 pages, no figures
Published: 2002
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42. Quantum Inozemtsev model, quasi-exact solvability and N-fold supersymmetry

Author: Sasaki, R. and Takasaki, K.
Subjects: High Energy Physics - Theory, Mathematical Physics, Mathematics - Quantum Algebra, Nonlinear Sciences - Exactly Solvable and Integrable Systems, Quantum Physics
Abstract: Inozemtsev models are classically integrable multi-particle dynamical systems related to Calogero-Moser models. Because of the additional q^6 (rational models) or sin^2(2q) (trigonometric models) potentials, their quantum versions are not exactly solvable in contrast with Calogero-Moser models. We show that quantum Inozemtsev models can be deformed to be a widest class of partly solvable (or quasi-exactly solvable) multi-particle dynamical systems. They posses N-fold supersymmetry which is equivalent to quasi-exact solvability. A new method for identifying and solving quasi-exactly solvable systems, the method of pre-superpotential, is presented., Comment: LaTeX2e 28 pages, no figures
Published: 2001
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43. On the Integrability of Classical Ruijsenaars-Schneider Model of $BC_{2}$ Type

Author: Inozemtsev, V. I. and Sasaki, R.
Subjects: High Energy Physics - Theory
Abstract: The problem of finding most general form of the classical integrable relativistic models of many-body interaction of the $BC_{n}$ type is considered. In the simplest nontrivial case of $n=2$,the extra integral of motion is presented in explicit form within the ansatz similar to the nonrelativistic Calogero-Moser models. The resulting Hamiltonian has been found by solving the set of two functional equations., Comment: 10 pages, LaTeX2e, no figures
Published: 2001
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44. Scalar Symmetries of the Hubbard Models with Variable Range Hopping

Author: Inozemtsev, V. I. and Sasaki, R.
Subjects: High Energy Physics - Theory, Condensed Matter, Nonlinear Sciences - Exactly Solvable and Integrable Systems
Abstract: Examples of scalar conserved currents are presented for trigonometric, hyperbolic and elliptic versions of the Hubbard model with non-nearest neighbour variable range hopping. They support for the first time the hypothesis about the integrability of the elliptic version. The two- electron wave functions are constructed in an explicit form., Comment: 9 pages, LaTex2e, no figures
Published: 2001
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45. Hierarchies of Spin Models related to Calogero-Moser Models

Author: Inozemtsev, V. I. and Sasaki, R.
Subjects: High Energy Physics - Theory, Condensed Matter, Mathematical Physics, Nonlinear Sciences - Exactly Solvable and Integrable Systems
Abstract: The universal formulation of spin exchange models related to Calogero-Moser models implies the existence of integrable hierarchies, which have not been explored. We show the general structures and features of the spin exchange model hierarchies by taking as examples the well-known Heisenberg spin chain with the nearest neighbour interactions. The energy spectra of the second member of the hierarchy belonging to the models based on the $A_r$ root systems $(r=3,4,5)$ are explicitly and {\em exactly} evaluated. They show many many interesting features and in particular, much higher degree of degeneracy than the original Heisenberg model, as expected from the integrability., Comment: 12pages, LaTeX2e, packages used: pstricks, pst-node, pstcol, if these are not available, an eps file will be sent upon request
Published: 2001
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46. Universal Lax pairs for Spin Calogero-Moser Models and Spin Exchange Models

Author: Inozemtsev, V. I. and Sasaki, R.
Subjects: High Energy Physics - Theory, Condensed Matter, Mathematical Physics, Mathematics - Dynamical Systems, Nonlinear Sciences - Exactly Solvable and Integrable Systems
Abstract: For any root system $\Delta$ and an irreducible representation ${\cal R}$ of the reflection (Weyl) group $G_\Delta$ generated by $\Delta$, a {\em spin Calogero-Moser model} can be defined for each of the potentials: rational, hyperbolic, trigonometric and elliptic. For each member $\mu$ of ${\cal R}$, to be called a "site", we associate a vector space ${\bf V}_{\mu}$ whose element is called a "spin". Its dynamical variables are the canonical coordinates $\{q_j,p_j\}$ of a particle in ${\bf R}^r$, ($r=$ rank of $\Delta$), and spin exchange operators $\{\hat{\cal P}_\rho\}$ ($\rho\in\Delta$) which exchange the spins at the sites $\mu$ and $s_{\rho}(\mu)$. Here $s_\rho$ is the reflection generated by $\rho$. For each $\Delta$ and ${\cal R}$ a {\em spin exchange model} can be defined. The Hamiltonian of a spin exchange model is a linear combination of the spin exchange operators only. It is obtained by "freezing" the canonical variables at the equilibrium point of the corresponding classical Calogero-Moser model. For $\Delta=A_r$ and ${\cal R}=$ vector representation it reduces to the well-known Haldane-Shastry model. Universal Lax pair operators for both spin Calogero-Moser models and spin exchange models are presented which enable us to construct as many conserved quantities as the number of sites for {\em degenerate} potentials., Comment: 18 pages, LaTeX2e, no figures
Published: 2001
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47. Quadratic Algebra associated with Rational Calogero-Moser Models

Author: Caseiro, R., Francoise, J. -P., and Sasaki, R.
Subjects: High Energy Physics - Theory, Condensed Matter, Mathematical Physics, Nonlinear Sciences - Exactly Solvable and Integrable Systems, Quantum Physics
Abstract: Classical Calogero-Moser models with rational potential are known to be superintegrable. That is, on top of the r involutive conserved quantities necessary for the integrability of a system with r degrees of freedom, they possess an additional set of r-1 algebraically and functionally independent globally defined conserved quantities. At the quantum level, Kuznetsov uncovered the existence of a quadratic algebra structure as an underlying key for superintegrability for the models based on A type root systems. Here we demonstrate in a universal way the quadratic algebra structure for quantum rational Calogero-Moser models based on any root systems., Comment: 19 pages, LaTeX2e, no figures
Published: 2001
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48. In-Situ Monitoring of Phase Transition and Microstructure Evolution in Ni-Based Superalloys by Electrical Resistivity: Direct Comparison With Differential Scanning Calorimetry and Application to Case Studies

Author: Utada, S, Sasaki, R, Reed, RC, and Tang, YT
Subjects: Mechanics of Materials, Metals and Alloys, Condensed Matter Physics
Abstract: In this study, resistivity measurements are made during continuous heating and cooling on four different Ni-based superalloys of different grain structures and with different phases (i.e., γ′ and carbide). The results are directly compared with differential scanning calorimetry (DSC) profiles to identify the material’s resistivity response. The resistivity measurements have been performed using an electro-thermal mechanical testing (ETMT) system having a capability of heating and cooling a sample at a rate of up to 100 K/s by Joule heating, which is not possible with standard heating methods used in previous in-situ microstructure analysis approaches. By comparing different precipitate variations and thermal histories, γ′ volume fraction and precipitate number density are found to be the most important factors determining the resistivity of the materials. In-situ resistivity measurement was applied to several case studies to show that it can provide microstructural information in complex high temperature experiments.
Published: 2022

49. Liouville Integrability of Classical Calogero-Moser Models

Author: Khastgir, S. P. and Sasaki, R.
Subjects: High Energy Physics - Theory, Condensed Matter, Mathematical Physics, Nonlinear Sciences - Exactly Solvable and Integrable Systems, Quantum Physics
Abstract: Liouville integrability of classical Calogero-Moser models is proved for models based on any root systems, including the non-crystallographic ones. It applies to all types of elliptic potentials, i.e. untwisted and twisted together with their degenerations (hyperbolic, trigonometric and rational), except for the rational potential models confined by a harmonic force., Comment: 8 pages, LaTeX2e, no figures
Published: 2000
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50. Quantum Calogero-Moser Models: Integrability for all Root Systems

Author: Khastgir, S. P., Pocklington, A. J., and Sasaki, R.
Subjects: High Energy Physics - Theory, Condensed Matter, Mathematical Physics, Nonlinear Sciences - Exactly Solvable and Integrable Systems, Quantum Physics
Abstract: The issues related to the integrability of quantum Calogero-Moser models based on any root systems are addressed. For the models with degenerate potentials, i.e. the rational with/without the harmonic confining force, the hyperbolic and the trigonometric, we demonstrate the following for all the root systems: (i) Construction of a complete set of quantum conserved quantities in terms of a total sum of the Lax matrix (L), i.e. (\sum_{\mu,\nu\in{\cal R}}(L^n)_{\mu\nu}), in which ({\cal R}) is a representation space of the Coxeter group. (ii) Proof of Liouville integrability. (iii) Triangularity of the quantum Hamiltonian and the entire discrete spectrum. Generalised Jack polynomials are defined for all root systems as unique eigenfunctions of the Hamiltonian. (iv) Equivalence of the Lax operator and the Dunkl operator. (v) Algebraic construction of all excited states in terms of creation operators. These are mainly generalisations of the results known for the models based on the (A) series, i.e. (su(N)) type, root systems., Comment: 45 pages, LaTeX2e, no figures
Published: 2000
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