Stephen L. Olsen, for the BESII Collaboration
Published 2003-05-17Version 1
We observe a narrow enhancement near 2m_p in the invariant mass spectrum of p\bar{p} pairs from radiative J/psi-->gamma p\bar{p} decays. No similar structure is seen in J/psi-->pi0 p\bar{p} decays. The results are based on an analysis of a 58 million event sample of J/psi decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit either with an S- or P-wave Breit Wigner resonance function; in the case of the S-wave fit, the peak mass is below 2m_p at M=1859 +3 -10(stat) +5 -25 (syst) MeV/c**2 and the total width is Gamma < 30 MeV/c**2, at the 90% confidence level. These mass and width values are not consistent with the properties of any known resonance.
Comments: 6 pages, 4 figures, invited talk at the International Symposium on Hadron Spectroscopy, Chiral Symmetry and Relativistic Description of Bound States, Nihon University, Ichigaya, Tokyo, February 24-26, 2003
Observation of a state $X(2600)$ in the $π^{+}π^{-}η'$ system in the process $J/ψ\rightarrowγπ^{+}π^{-}η'$
Observation of a structure at 1.84 GeV/c$^2$ in the $3(π^+π^-)$ mass spectrum in $J/ψ\rightarrow γ3(π^+π^-)$ decays
Observation of Y(2175) in $J/ψ\to ηφf_0(980)$
