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Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/131518
Observation of e+e−→ρ+ρ− near √s=10.58 GeV
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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.
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GARRA TICÓ, Jordi, GRAUGÉS POUS, Eugeni and BABAR Collaboration. Observation of e+e−→ρ+ρ− near √s=10.58 GeV. Physical Review D. 2008. Vol. 78, num. 7, pags. 071103. ISSN 1550-7998. [consulted: 11 of August of 2026]. Available at: https://hdl.handle.net/2445/131518