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Study of the reaction e^{+}e^{-}->psi(2S)pi^{-}pi^{-} via initial state radiation at BaBar
J. P. Lees1, V. Poireau1, V. Tisserand1, N. Arnaud2, M. Davier2, D. Derkach2, G. Grosdidier2, F. Le Diberder2, A. M. Lutz2, B. Malaescu2, P. Roudeau2, M. H. Schune2, A. Stocchi2, G. Wormser2, D. Bernard3, M. Verderi3, S. Emery4, G. Hamel de Monchenault4, G. Vasseur4, Ch. Yèche4, S. Akar5, E. Ben-Haim5, M. Bomben5, G.R. Bonneaud5, H. Briand5, G. Calderini5, J. Chauvau5, O. Hamon5, Ph. Leruste5, G. Marchiori5, J. Ocariz5, S. Sitt5
BABAR Collaboration(s)

We study the process $e^+e^-\to\psi(2S)\pi^{+}\pi^{-}$ 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 $\Upsilon(\mathrm{nS})$ (n = 2, 3, 4) resonances and correspond to an integrated luminosity of 520$fb^{-}$. We investigate the $\psi(2S)\pi^{+}\pi^{-}$ mass distribution from 3.95 to 5.95 $GeV/c^{2}$, and measure the center-of-mass energy dependence of the associated $e^+e^-\to \psi(2S)\pi^{+}\pi^{-}$ cross section. The mass distribution exhibits evidence of two resonant structures. A fit to the $\psi(2S)\pi^{+}\pi^{-}$ mass distribution corresponding to the decay mode $\psi(2S)\to J/\psi \pi^{+}\pi^{-}$ yields a mass value of $4340 \pm16$ (stat) $\pm 9$ (syst) ${\mathrm {MeV/c^{2}}}and a width of $94 \pm 32$ (stat) $\pm 13$ (syst) MeV for the first resonance, and for the second a mass value of $4669 \pm 21$ (stat) $\pm 3$ (syst) ${\mathrm {MeV/c^{2}}}$ and a width of $104 \pm 48$ (stat) $\pm 10$ (syst) MeV. In addition, we show the $pi^{+}\pi^{-}$ mass distributions for these resonant regions.
1 :  LAPP - Laboratoire d'Annecy le Vieux de Physique des Particules
2 :  LAL - Laboratoire de l'Accélérateur Linéaire
3 :  LLR - Laboratoire Leprince-Ringuet
4 :  IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers (ex DAPNIA)
5 :  LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies
Physique/Physique des Hautes Energies - Expérience
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