Measurements of the mass, total width, and two-photon partial width of the eta(c) meson

Abstract

Using 13.4 fb(-1) of data collected with the CLEO detector at the Cornell Electron Storage Ring, we have observed 300 events for the two-photon production of ground-state pseudoscalar charmonium in the decay eta(c) --> K(S)(0)K(+/-)pi(+/-). We have measured the eta(c) mass to be [2980.4 +/- 2.3 (stat) +/- 0.6 (syst)] MeV and its full width as [27.0 +/- 5.8 (stat) +/- 1.4 (syst)] MeV. We have determined the two-photon partial width of the eta(c) meson to be [7.6 +/- 0.8 (stat) +/- 0.4 (syst) +/- 2.3 (br)] keV, with the last uncertainty associated with the decay branching fraction.