UC Berkeley

We study the process γγ→J/ψω using a data sample of 519.2fb -1 recorded by the BABAR detector at SLAC at the PEP-II asymmetric-energy e +e - collider at center-of-mass energies near the Υ(nS) (n=2,3,4) resonances. We confirm the existence of the charmoniumlike resonance X(3915) decaying to J/ψω with a significance of 7.6 standard deviations, including systematic uncertainties, and measure its mass (3919.4±2.2±1.6)MeV/c2 and width (13±6±3)MeV, where the first uncertainty is statistical and the second systematic. A spin-parity analysis supports the assignment JP=0 + and therefore the identification of the signal as due to the χ c0(2P) resonance. In this hypothesis we determine the product between the two-photon width and the final state branching fraction to be (52±10±3)eV. © 2012 American Physical Society.