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Physical Review D 86 (2012) 072002
Study of X(3915) --> J/\psi \omega\ in two-photon collisions
J. P. Lees1, V. Poireau1, V. Tisserand1, D. Bernard2, M. Verderi2, S. Emery3, G. Hamel de Monchenault3, G. Vasseur3, Ch. Yèche3, N. Arnaud4, M. Davier4, D. Derkach4, G. Grosdidier4, F. Le Diberder4, A. M. Lutz4, B. Malaescu4, P. Roudeau4, M. H. Schune4, A. Stocchi4, G. Wormser4, 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
For the BABAR collaboration(s)

We study the process $\gamma \gamma \to J/\psi \omega$ using a data sample of 519.2 $fb^{-1}$ recorded by the BaBar detector at SLAC at the PEP-II asymmetric-energy $e^+ e^-$ collider at center-of-mass energies near the $\Upsilon(nS)$ ($n = 2,3,4$) resonances. We confirm the existence of the charmonium-like resonance X(3915) decaying to $J/\psi \omega$ with a significance of 7.6 standard deviations, including systematic uncertainties, and measure its mass $(3919.4 \pm 2.2 \pm 1.6) MeV/c^2$ and width $(13 \pm 6 \pm 3) MeV$, where the first uncertainty is statistical and the second systematic. A spin-parity analysis supports the assignment $J^P=0^+$ and therefore the ident ification of the signal as due to the $\chi_{c0}(2P)$ resonance. In this hypothesis we determine the product between the two-photon width and the final state branching fraction to be $(52 \pm 10 \pm 3) eV$
1:  LAPP - Laboratoire d'Annecy le Vieux de Physique des Particules
2:  LLR - Laboratoire Leprince-Ringuet
3:  IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers (ex DAPNIA)
4:  LAL - Laboratoire de l'Accélérateur Linéaire
5:  LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies
Physics/High Energy Physics - Experiment
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