New measurements of the resonance parameters of the χc0(13P0) state of charmonium

Abstract The resonance parameters of the χ c 0 , the 1 3 P 0 state of charmonium, have been measured at the Fermilab Antiproton Accumulator in the reaction p p→χ c0 →γJ/ψ→γ(e + e − ) . A large data sample collected during the year 2000 run yields the results: M ( χ c 0 )=3415.4±0.4±0.2 MeV/ c 2 , Γ ( χ c 0 )=9.8±1.0±0.1 MeV, B (χ c0 → p p)× B (χ c0 →γJ/ψ)× B (J/ψ→(e + e − ))=(1.61±0.11±0.08)×10 −7 . Taking B (χ c0 →γJ/ψ) and B (J/ψ→e + e − ) from the literature, we obtain B (χ c0 → p p)=(4.1±0.3 +1.6 −0.9 )×10 −4 and Γ(χ c0 → p p)=(4.0±0.4 +1.6 −0.9 )  keV.