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Aubert, B.; Lees, J. P.; Prudent, X.; Tisserand, V.; Lopez, L.; Stugu, B.; Abrams, G. S.; Brown, D. N.; Jacobsen, R. G.; Kolomensky, Yu. G.; Kukartsev, G.; Osipenkov, I. L.; Hawkes, C. M.; Soni, N.; Teodorescu, L.; Buzykaev, A. R.; Onuchin, A. P.; Curry, S.; Kirkby, D.; Lankford, A. J.; Abachi, S.; Long, O.; Porter, F. C.; Gaz, A.; Kreisel, A.; Ayad, R.; Toki, W. H.; Petzold, A.; Spaan, B.; Mader, W. F.; Gradl, W.; Cibinetto, G.; Franchini, P.; Petrella, A.; Piccolo, M.; Patrignani, C.; Schenk, S.; Vazquez, W. Panduro; Chai, X.; Cochran, J.; Crawley, H. B.; Arnaud, N.; Lutz, A. M.; Pruvot, S.; Stocchi, A.; Wright, D. M.; Gamet, R.; Payne, D. J.; Bevan, A. J.; Clarke, C. K.; Lodovico, F. Di; Hopkins, D. A.; Yi, J. I.; Anderson, J.; Dallapiccola, C.; Saremi, S.; Spitznagel, M.; Lombardo, V.; Palombo, F.; Bauer, J. M.; Zhao, H. W.; Onorato, G.; Jessop, C. P.; Regensburger, J. J.; Igonkina, O.; Lu, M.; Rahmat, R.; Briand, H.; Hamon, O.; Gladney, L.; Bettarini, S.; Baracchini, E.; del Re, D.; Gioi, L. Li; Renga, F.; Waldi, R.; Emery, S.; Esteve, L.; Purohit, M. V.; Aston, D.; Gowdy, S. J.; Kaminski, J.; Li, S.; Luitz, S.; Ratcliff, B. N.; Thompson, J. M.; West, C. A.; Wisniewski, W. J.; Wittgen, M.; Ahmed, S.; Pan, B.; Zain, S. B.; Eckmann, R.; Della Ricca, G.; Martinez-Vidal, F.; Albert, J.; Nugent, I. M.; Roney, J. M.; Gershon, T. J.; Prepost, R.
Physical review. D, Particles, fields, gravitation, and cosmology, 10/2008, Letnik: 78, Številka: 7Journal Article
We report the first observation of e + e − → ρ + ρ − , in a data sample of 379 fb − 1 collected with the BABAR detector at the PEP-II e + e − storage ring at center-of-mass energies near √ s = 10.58 GeV . We measure a cross section of σ ( e + e − → ρ + ρ − ) = 8.3 ± 0.7 ( stat ) ± 0.8 ( syst ) fb within the range of | cos θ ∗ | < 0.8 and | cos θ ± | < 0.85 , where θ ∗ is the center-of-mass polar angle of the ρ ± meson and θ ± are the angles in the ρ ± rest frame between the direction of the boost from the laboratory frame and the direction of the π ± . Assuming production through single-photon annihilation, there are three independent helicity amplitudes. We measure the ratios of their squared moduli to be | F 00 | 2 ∶ | F 10 | 2 ∶ | F 11 | 2 = 0.51 ± 0.14 ( stat ) ± 0.07 ( syst ) ∶ 0.10 ± 0.04 ( stat ) ± 0.01 ( syst ) ∶ 0.04 ± 0.03 ( stat ) ± 0.01 ( syst ) . The | F 00 | 2 result is inconsistent with the prediction of 1.0 made by QCD models with a significance of 3.1 standard deviations including systematic uncertainties.
