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Study of the reaction e+e- → ψ (2S)π+π- via initial-state radiation at B a B ar Garra Ticó, Jordi Graugés Pous, Eugeni BABAR Collaboration Massa (Física) Radiació Energia Física de partícules Mass (Physics) Radiation Energy Particle physics We study the process e + e − → ψ ( 2 S ) π + π − with initial-state-radiation events produced at the PEP-II asymmetric-energy collider. The data were recorded with the BABAR detector at center-of-mass energies at and near the Υ ( nS ) ( n = 2 , 3 , 4 ) resonances and correspond to an integrated luminosity of 520     fb − 1 . We investigate the ψ ( 2 S ) π + π − mass distribution from 3.95 to 5.95     GeV / c 2 , and measure the center-of-mass energy dependence of the associated e + e − → ψ ( 2 S ) π + π − cross section. The mass distribution exhibits evidence of two resonant structures. A fit to the ψ ( 2 S ) π + π − mass distribution corresponding to the decay mode ψ ( 2 S ) → J / ψ π + π − yields a mass value of 4340 ± 16   ( stat )   ± 9   ( syst )     MeV / c 2   and a width of 94 ± 32   ( stat )   ± 13   ( syst )     MeV for the first resonance, and for the second a mass value of 4669 ± 21   ( stat )   ± 3   ( syst )     MeV / c 2   and a width of 104 ± 48   ( stat )   ± 10   ( syst )     MeV . In addition, we show the π + π − mass distributions for these resonant regions. 2019-03-25T11:51:30Z 2019-03-25T11:51:30Z 2014-06-25 2019-03-25T11:51:30Z info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Reproducció del document publicat a: https://doi.org/10.1103/PhysRevD.89.111103 Physical Review D, 2014, vol. 89, num. 11, p. 111103 https://doi.org/10.1103/PhysRevD.89.111103 (c) American Physical Society, 2014 info:eu-repo/semantics/openAccess American Physical Society Articles publicats en revistes (Física Quàntica i Astrofísica)