Using a sample of 771.6 x 10(6) Upsilon Upsilon(4S) decays collected by the Belle experiment at the KEKB e(+)e(-) collider, we observe, for the first time, the transition Upsilon(4S) -> eta h(b)(1P) with the branching fraction B[Upsilon(4S) -> eta h(b)(1P)] = (2.18 +/- 0.11 +/- 0.18) x 10(-3) and we measure the h(b)(1P) mass M-hb(1P) = (9899.3 +/- 0.4 +/- 1.0) MeV/c(2), corresponding to the hyperfine (HF) splitting Delta M-HF(1P) = (0.6 +/- 0.4 +/- 1.0) MeV/c(2). Using the transition h(b)(1P) -> gamma eta(b)(1S), we measure the eta(b)(1S) mass M-eta b(1S) = (9400.7 +/- 1.7 +/- 1.6) MeV/c(2), corresponding to Delta M-HF(1S) = (59.6 +/- 1.7 +/- 1.6) MeV/c(2), the eta(b)(1S) width Gamma(eta b)(1S) = (8(-5)(+6)+/- 5) MeV/c(2) and the branching fraction B[h(b)(1P) -> gamma eta(b)(1S)] = (56 +/- 8 +/- 4)%.
Jian Wang, Lesya Shchutska, Olivier Schneider, Yiming Li, Yi Zhang, Aurelio Bay, Guido Haefeli, Christoph Frei, Frédéric Blanc, Tatsuya Nakada, Michel De Cian, François Fleuret, Elena Graverini, Renato Quagliani, Federico Betti, Aravindhan Venkateswaran, Vitalii Lisovskyi, Sebastian Schulte, Veronica Sølund Kirsebom, Elisabeth Maria Niel, Ettore Zaffaroni, Mingkui Wang, Zhirui Xu, Chao Wang, Lei Zhang, Ho Ling Li, Mark Tobin, Minh Tâm Tran, Niko Neufeld, Matthew Needham, Maurizio Martinelli, Vladislav Balagura, Donal Patrick Hill, Liang Sun, Xiaoxue Han, Liupan An, Federico Leo Redi, Maxime Schubiger, Hang Yin, Violaine Bellée, Preema Rennee Pais, Pavol Stefko, Tara Nanut, Maria Elena Stramaglia, Yao Zhou, Tommaso Colombo, Vladimir Macko, Guillaume Max Pietrzyk, Evgenii Shmanin, Maxim Karpov, Simone Meloni, Xiaoqing Zhou, Surapat Ek-In, Carina Trippl, Sara Celani, Marco Guarise, Serhii Cholak, Dipanwita Dutta, Zheng Wang, Yong Yang, Yi Wang, Hao Liu, Hans Dijkstra, Gerhard Raven, Peter Clarke, Frédéric Teubert, Giovanni Carboni, Victor Coco, Shuai Liu, Adam Davis, Paolo Durante, Yu Zheng, Anton Petrov, Maxim Borisyak, Feng Jiang, Alexey Boldyrev, Almagul Kondybayeva, Hossein Afsharnia
Olivier Schneider, Yiming Li, Mingkui Wang, Chao Wang, Tagir Aushev, Sun Hee Kim, Donghyun Kim, Xiao Wang
Jian Wang, Olivier Schneider, Yiming Li, Yi Zhang, Aurelio Bay, Guido Haefeli, Christoph Frei, Frédéric Blanc, Tatsuya Nakada, Michel De Cian, Luca Pescatore, François Fleuret, Elena Graverini, Chitsanu Khurewathanakul, Renato Quagliani, Maria Vieites Diaz, Federico Betti, Aravindhan Venkateswaran, Luis Miguel Garcia Martin, Vitalii Lisovskyi, Mingkui Wang, Zhirui Xu, Lei Zhang, Jessica Prisciandaro, Mark Tobin, Minh Tâm Tran, Niko Neufeld, Matthew Needham, Marc-Olivier Bettler, Greig Alan Cowan, Maurizio Martinelli, Vladislav Balagura, Donal Patrick Hill, Cédric Potterat, Liang Sun, Pietro Marino, Mirco Dorigo, Jean Wicht, Xiaoxue Han, Sebastiana Gianì, Liupan An, Federico Leo Redi, Plamen Hristov Hopchev, Thibaud Humair, Maxime Schubiger, Hang Yin, Guido Andreassi, Violaine Bellée, Olivier Göran Girard, Axel Kuonen, Preema Rennee Pais, Pavol Stefko, Maria Elena Stramaglia, Tommaso Colombo, Vladimir Macko, Guillaume Max Pietrzyk, Lino Ferreira Lopes, Dipanwita Dutta, Yi Wang, Hans Dijkstra, Gerhard Raven, Peter Clarke, Frédéric Teubert, Giovanni Carboni, Victor Coco, Adam Davis, Paolo Durante, Yu Zheng, Anton Petrov, Maxim Borisyak, Feng Jiang, Zhipeng Tang, Luis Alberto Granado Cardoso, Daniel Hugo Cámpora Pérez