Observation of a narrow, near-threshold enhancement in the p\bar{p} mass spectrum from radiative J/psi--> gamma p\bar{p} decays
arXiv: High Energy Physics - Experiment(2003)
摘要
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.
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关键词
high energy physics,confidence level,spectrum
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