posted on 2024-08-06, 09:42authored byI. Adachi, H. Aihara, K. Arinstein, D. M. Asner, T. Aushev, T. Aziz, A. M. Bakich, E. Barberio, K. Belous, V. Bhardwaj, B. Bhuyan, A. Bondar, M. Bračko, J. Brodzicka, T. E. Browder, P. Chang, A. Chen, P. Chen, B. G. Cheon, K. Chilikin, R. Chistov, I.-S. Cho, K. Cho, Y. Choi, J. Dalseno, M. Danilov, Z. Drásal, A. Drutskoy, S. Eidelman, D. Epifanov, S. Esen, J. E. Fast, M. Feindt, V. Gaur, N. Gabyshev, A. Garmash, Y. M. Goh, B. Golob, T. Hara, K. Hayasaka, H. Hayashii, Y. Hoshi, W.-S. Hou, Y. B. Hsiung, H. J. Hyun, T. Iijima, A. Ishikawa, M. Iwabuchi, Y. Iwasaki, I. Jaegle, T'Mir Julius, J. H. Kang, N. Katayama, T. Kawasaki, H. Kichimi, H. O. Kim, J. B. Kim, K. T. Kim, M. J. Kim, Y. J. Kim, K. Kinoshita, B. R. Ko, N. Kobayashi, S. Koblitz, S. Korpar, P. Križan, T. Kuhr, T. Kumita, A. Kuzmin, Y.-J. Kwon, J. S. Lange, S.-H. Lee, J. Li, J. Libby, C. Liu, D. Liventsev, R. Louvot, J. MacNaughton, D. Matvienko, S. McOnie, K. Miyabayashi, H. Miyata, Y. Miyazaki, R. Mizuk, G. B. Mohanty, R. Mussa, Y. Nagasaka, E. Nakano, M. Nakao, H. Nakazawa, Z. Natkaniec, S. Neubauer, S. Nishida, K. Nishimura, O. Nitoh, T. Nozaki, T. Ohshima, S. Okuno, S. L. Olsen, Y. Onuki, P. Pakhlov, G. Pakhlova, H. Park, T. K. Pedlar, R. Pestotnik, M. Petrič, L. E. Piilonen, A. Poluektov, M. Ritter, M. Röhrken, S. Ryu, H. Sahoo, Y. Sakai, T. Sanuki, O. Schneider, C. Schwanda, A. J. Schwartz, K. Senyo, O. Seon, M. E. Sevior, M. Shapkin, V. Shebalin, T.-A. Shibata, J.-G. Shiu, B. Shwartz, F. Simon, P. Smerkol, Y.-S. Sohn, A. Sokolov, E. Solovieva, S. Stanič, M. Starič, M. Sumihama, G. Tatishvili, Y. Teramoto, I. Tikhomirov, K. Trabelsi, M. Uchida, S. Uehara, T. Uglov, Y. Unno, S. Uno, S. E. Vahsen, G. Varner, K. E. Varvell, A. Vinokurova, C. H. Wang, X. L. Wang, Y. Watanabe, J. Wicht, E. Won, B. D. Yabsley, Y. Yamashita, C. Z. Yuan, V. Zhilich, A. Zupanc
We report the first observations of the spin-singlet bottomonium states hb(1P) and hb(2P). The states are produced in the reaction e+e−→hb(nP)π+π− using a 121.4 fb−1 data sample collected at energies near the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We determine M[hb(1P)]=(9898.2+1.1+1.0−1.0−1.1) MeV/c2 and M[hb(2P)]=(10 259.8±0.6+1.4−1.0) MeV/c2, which correspond to P-wave hyperfine splittings ΔMHF=(+1.7±1.5) and (+0.5+1.6−1.2) MeV/c2, respectively. The significances of the hb(1P) and hb(2P) are 5.5σ and 11.2σ, respectively. We find that the production of the hb(1P) and hb(2P) is not suppressed relative to the production of the Υ(1S), Υ(2S), and Υ(3S).