We report the first measurement of the lepton forward-backward asymmetry A(FB) as a function of the squared four-momentum of the dilepton system, q(2), for the electroweak penguin process B -> X(s)l(+)l(-) with a sum of exclusive final states, where l is an electron or a muon and X-s is a hadronic recoil system with an s quark. The results are based on a data sample containing 772 x 10(6) B (B) over bar pairs recorded at the gamma (4S) resonance with the Belle detector at the KEKB e(+)e(-) collider. A(FB) for the inclusive B -> X(s)l(+)l(-) is extrapolated from the sum of 10 exclusive X-s states whose invariant mass is less than 2 GeV/c(2). For q(2) > 10.2 GeV2/c(2), A(FB) < 0 is excluded at the 2.3 sigma level, where sigma is the standard deviation. For q(2) < 4.3 GeV2/c(2), the result is within 1.8 sigma of the standard model theoretical expectation.
Julia Schmale, Ivo Fabio Beck, Benjamin Jérémy Laurent Heutte, Nora Bergner, Hélène Paule Angot, Lubna Dada
Julia Schmale, Ivo Fabio Beck, Benjamin Jérémy Laurent Heutte, Lubna Dada
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