1203.0940 (The Super-Kamiokande Collaboration: K. Ueno et al.)

Search for GUT Monopoles at Super-Kamiokande    [PDF]

The Super-Kamiokande Collaboration: K. Ueno, K. Abe, Y. Hayato, T. Iida, K. Iyogi, J. Kameda, Y. Koshio, Y. Kozuma, M. Miura, S. Moriyama, M. Nakahata, S. Nakayama, Y. Obayashi, H. Sekiya, M. Shiozawa, Y. Suzuki, A. Takeda, Y. Takenaga, K. Ueshima, S. Yamada, T. Yokozawa, K. Martens, J. Schuemann, M. Vagins, C. Ishihara, H. Kaji, T. Kajita, K. Kaneyuki, T. McLachlan, K. Okumura, Y. Shimizu, N. Tanimoto, E. Kearns, M. Litos, J. L. Raaf, J. L. Stone, L. R. Sulak, K. Bays, W. R. Kropp, S. Mine, C. Regis, A. Renshaw, M. B. Smy, H. W. Sobel, K. S. Ganezer, J. Hill, W. E. Keig, J. S. Jang, J. Y. Kim, I. T. Lim, J. B. Albert, K. Scholberg, C. W. Walter, R. Wendell, T. Wongjirad, T. Ishizuka, S. Tasaka, J. G. Learned, S. Matsuno, T. Hasegawa, T. Ishida, T. Ishii, T. Kobayashi, T. Nakadaira, K. Nakamura, K. Nishikawa, Y. Oyama, K. Sakashita, T. Sekiguchi, T. Tsukamoto, A. T. Suzuki, Y. Takeuchi, M. Ikeda, A. Minamino, T. Nakaya, L. Labarga, Ll. Marti, Y. Fukuda, Y. Itow, G. Mitsuka, T. Tanaka, C. K. Jung, G. Lopez, I. Taylor, C. Yanagisawa, H. Ishino, A. Kibayashi, S. Mino, T. Mori, M. Sakuda, H. Toyota, Y. Kuno, M. Yoshida, S. B. Kim, B. S. Yang, H. Okazawa, Y. Choi, K. Nishijima, M. Koshiba, Y. Totsuka, M. Yokoyama, S. Chen, Y. Heng, Z. Yang, H. Zhang, D. Kielczewska, P. Mijakowski, K. Connolly, M. Dziomba, E. Thrane, R. J. Wilkes

GUT monopoles captured by the Sun's gravitation are expected to catalyze proton decays via the Callan-Rubakov process. In this scenario, protons, which initially decay into pions, will ultimately produce \nu_{e}, \nu_{\mu} and \bar{\nu}_{\mu}. After undergoing neutrino oscillation, all neutrino species appear when they arrive at the Earth, and can be detected by a 50,000 metric ton water Cherenkov detector, Super-Kamiokande (SK). A search for low energy neutrinos in the electron total energy range from 19 to 55 MeV was carried out with SK and gives a monopole flux limit of F_M(\sigma_0/1 mb) < 6.3 \times 10^{-24} (\beta_M/10^{-3})^2 cm^{-2} s^{-1} sr^{-1} at 90% C.L., where \beta_M is the monopole velocity in units of the speed of light and \sigma_0 is the catalysis cross section at \beta_M=1. The obtained limit is more than eight orders of magnitude more stringent than the current best cosmic-ray supermassive monopole flux limit, F_M < 1 \times 10^{-15} cm^{-2} s^{-1} sr^{-1} for \beta_M < 10^{-3} and also two orders of magnitude lower than the result of the Kamiokande experiment, which used a similar detection method.

View original: http://arxiv.org/abs/1203.0940