Evidence for the η b ( 1 S ) Meson in Radiative Υ ( 2 S ) Decay

We have performed a search for the η b ( 1 S ) meson in the radiative decay of the Υ ( 2 S ) resonance using a sample of 91.6 × 10 6 Υ ( 2 S ) events recorded with the BABAR detector at the PEP-II B factory at the SLAC National Accelerator Laboratory. We observe a peak in the photon energy spectrum...

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Veröffentlicht in:Physical review letters 2009-10, Vol.103 (16), Article 161801
Hauptverfasser: Aubert, B., Bona, M., Karyotakis, Y., Lees, J. P., Poireau, V., Prencipe, E., Prudent, X., Tisserand, V., Garra Tico, J., Grauges, E., Lopez, L., Palano, A., Pappagallo, M., Eigen, G., Stugu, B., Sun, L., Battaglia, M., Brown, D. N., Kerth, L. T., Kolomensky, Yu. G., Lynch, G., Osipenkov, I. L., Tackmann, K., Tanabe, T., Hawkes, C. M., Soni, N., Watson, A. T., Koch, H., Schroeder, T., Asgeirsson, D. J., Fulsom, B. G., Hearty, C., Mattison, T. S., McKenna, J. A., Barrett, M., Khan, A., Randle-Conde, A., Blinov, V. E., Bukin, A. D., Buzykaev, A. R., Druzhinin, V. P., Golubev, V. B., Onuchin, A. P., Serednyakov, S. I., Skovpen, Yu. I., Solodov, E. P., Todyshev, K. Yu, Bondioli, M., Curry, S., Eschrich, I., Kirkby, D., Lankford, A. J., Lund, P., Mandelkern, M., Martin, E. C., Stoker, D. P., Abachi, S., Buchanan, C., Atmacan, H., Gary, J. W., Liu, F., Long, O., Vitug, G. M., Yasin, Z., Zhang, L., Sharma, V., Campagnari, C., Hong, T. M., Kovalskyi, D., Mazur, M. A., Richman, J. D., Beck, T. W., Eisner, A. M., Heusch, C. A., Kroseberg, J., Lockman, W. S., Martinez, A. J., Schalk, T., Schumm, B. A., Seiden, A., Winstrom, L. O., Cheng, C. H., Doll, D. A., Echenard, B., Fang, F., Hitlin, D. G., Narsky, I., Piatenko, T., Porter, F. C., Andreassen, R., Mancinelli, G., Meadows, B. T., Mishra, K., Sokoloff, M. D., Bloom, P. C., Ford, W. T., Gaz, A., Hirschauer, J. F., Nagel, M., Nauenberg, U.
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Sprache:eng
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Zusammenfassung:We have performed a search for the η b ( 1 S ) meson in the radiative decay of the Υ ( 2 S ) resonance using a sample of 91.6 × 10 6 Υ ( 2 S ) events recorded with the BABAR detector at the PEP-II B factory at the SLAC National Accelerator Laboratory. We observe a peak in the photon energy spectrum at E γ = 609.3 + 4.6 − 4.5 ( stat ) ± 1.9 ( syst )     MeV , corresponding to an η b ( 1 S ) mass of 9394.2 + 4.8 − 4.9 ( stat ) ± 2.0 ( syst )     MeV / c 2 . The branching fraction for the decay Υ ( 2 S ) → γ η b ( 1 S ) is determined to be [ 3.9 ± 1.1 ( stat ) + 1.1 − 0.9 ( syst ) ] × 10 − 4 . We find the ratio of branching fractions B [ Υ ( 2 S ) → γ η b ( 1 S ) ] / B [ Υ ( 3 S ) → γ η b ( 1 S ) ] = 0.82 ± 0.24 ( stat ) + 0.20 − 0.19 ( syst ) .
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.103.161801