1205.1246 (Belle Collaboration et al.)

First observation of exclusive $Υ(1S)$ and $Υ(2S)$ decays
into light hadrons    [PDF]

Belle Collaboration, C. P. Shen, C. Z. Yuan, T. Iijima, I. Adachi, H. Aihara, D. M. Asner, T. Aushev, A. M. Bakich, A. Bay, K. Belous, B. Bhuyan, M. Bischofberger, G. Bonvicini, A. Bozek, M. Bračko, T. E. Browder, M. -C. Chang, P. Chang, A. Chen, P. Chen, B. G. Cheon, K. Chilikin, R. Chistov, I. -S. Cho, K. Cho, S. -K. Choi, Y. Choi, J. Dalseno, Z. Doležal, Z. Drásal, S. Eidelman, J. E. Fast, V. Gaur, N. Gabyshev, Y. M. Goh, B. Golob, J. Haba, H. Hayashii, Y. Horii, Y. Hoshi, W. -S. Hou, Y. B. Hsiung, H. J. Hyun, K. Inami, A. Ishikawa, R. Itoh, M. Iwabuchi, Y. Iwasaki, T. Iwashita, T. Julius, J. H. Kang, T. Kawasaki, C. Kiesling, B. H. Kim, H. O. Kim, J. B. Kim, J. H. Kim, M. J. Kim, Y. J. Kim, K. Kinoshita, B. R. Ko, S. Koblitz, P. Kodyš, S. Korpar, R. T. Kouzes, P. Križan, P. Krokovny, R. Kumar, T. Kumita, A. Kuzmin, Y. -J. Kwon, S. -H. Lee, J. Li, Y. Li, J. Libby, C. Liu, Y. Liu, Z. Q. Liu, R. Louvot, S. McOnie, K. Miyabayashi, H. Miyata, G. B. Mohanty, D. Mohapatra, A. Moll, N. Muramatsu, E. Nakano, M. Nakao, Z. Natkaniec, S. Nishida, K. Nishimura, O. Nitoh, S. Ogawa, T. Ohshima, S. Okuno, S. L. Olsen, P. Pakhlov, G. Pakhlova, C. W. Park, H. Park, H. K. Park, T. K. Pedlar, R. Pestotnik, M. Petrič, L. E. Piilonen, M. Ritter, H. Sahoo, Y. Sakai, D. Santel, T. Sanuki, Y. Sato, O. Schneider, C. Schwanda, K. Senyo, O. Seon, M. E. Sevior, M. Shapkin, V. Shebalin, T. -A. Shibata, J. -G. Shiu, B. Shwartz, A. Sibidanov, F. Simon, P. Smerkol, Y. -S. Sohn, A. Sokolov, E. Solovieva, M. Starič, M. Sumihama, T. Sumiyoshi, G. Tatishvili, Y. Teramoto, M. Uchida, S. Uehara, T. Uglov, Y. Unno, S. Uno, P. Urquijo, Y. Usov, P. Vanhoefer, G. Varner, C. H. Wang, P. Wang, X. L. Wang, M. Watanabe, Y. Watanabe, K. M. Williams, E. Won, B. D. Yabsley, Y. Yamashita, C. C. Zhang, Z. P. Zhang, V. Zhilich, V. Zhulanov, A. Zupanc

Using samples of 102 million $\Upsilon(1S)$ and 158 million $\Upsilon(2S)$ events collected with the Belle detector, we study exclusive hadronic decays of these two bottomonium resonances to the three-body final states $\phi K^+ K^-$, $\omega \pi^+ \pi^-$ and $K^{\ast 0}(892) K^- \pi^+ $, and to the two-body Vector-Tensor ($\phi f_2'(1525)$, $\omega f_2(1270)$, $\rho a_2(1320)$ and $K^{\ast 0}(892) \bar{K}_2^{\ast 0}(1430) $) and Axial-vector-Pseudoscalar ($K_1(1270)^+ K^-$, $K_1(1400)^+ K^- $ and $b_1(1235)^+ \pi^- $) pairs. Signals are observed for the first time in the $\Upsilon(1S) \to \phi K^+ K^-$, $\omega \pi^+ \pi^-$, $K^{\ast 0} K^- \pi^+$, $K^{\ast0} K_2^{\ast 0}$ and $\Upsilon(2S) \to \phi K^+ K^-$, $K^{\ast 0} K^- \pi^+$ decay modes. Branching fractions are determined for all the processes, while 90% confidence level upper limits are established on the branching fractions for the modes with a statistical significance less than $3\sigma$. The ratios of the branching fractions of $\Upsilon(2S)$ and $\Upsilon(1S)$ decays into the same final state are used to test a perturbative QCD prediction for OZI suppressed bottomonium decays.

View original: http://arxiv.org/abs/1205.1246