Measurements of the mass and width of the etac meson and of an etac(2S) candidate
Abstract
The mass and total width of the etac meson have been measured in two-photon interactions at the SLAC asymmetric B-Factory with the BABAR detector. With a sample of approximately 2500 reconstructed etac -> Ks K pi decays in 88 fb-1 of data, the measured etac mass and width are respectively 2982.5 +- 1.1 (stat) +- 0.9 (syst) MeV/c2 and 34.3 +- 2.3 (stat) +- 0.9 (syst) MeV/c2. Using the same decay mode, a second resonance with 112 +- 24 events is observed with a mass of 3630.8 +- 3.4 (stat) +- 1.0 (syst) MeV/c2 and width of 17.0 +- 8.3 (stat) +- 2.5 (syst) MeV/c2. This observation is consistent with expectations for the etac(2S) state.
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