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Observation of Y(2175) in J/psi --> etaphif0 (980)
1Institute of High Energy Physics, Beijing 100049, People's Republic of China.
Physical Review Letters
|March 21, 2008
Summary
Researchers analyzed J/psi decays and observed a new structure, Y(2175), in the phi f(0)(980) invariant mass spectrum. This finding provides new insights into charmonium physics and exotic meson spectroscopy.
Area of Science:
- Particle Physics
- High Energy Physics
- Quantum Chromodynamics
Background:
- The J/psi meson is a crucial probe for studying charmonium spectroscopy.
- Understanding the nature of scalar and vector mesons is essential for advancing quantum chromodynamics (QCD).
Purpose of the Study:
- To investigate the decays of J/psi into eta phi f(0)(980).
- To search for and characterize new resonant structures in the phi f(0)(980) invariant mass spectrum.
Main Methods:
- Analysis of 5.8 x 10^7 J/psi events collected by the BESII detector.
- Reconstruction of the eta, phi, and f(0)(980) mesons through their respective decay channels.
- Fit of the phi f(0)(980) invariant mass spectrum using a Breit-Wigner function.
Main Results:
- Observation of a significant structure (approx. 5 sigma) around 2.18 GeV/c^2 in the phi f(0)(980) mass spectrum.
- Determination of the resonance parameters: mass m = 2.186 +/- 0.010(stat) +/- 0.006(syst) GeV/c^2 and width Gamma = 0.065 +/- 0.023(stat) +/- 0.017(syst) GeV/c^2.
- Measurement of the production branching ratio Br(J/psi --> eta Y(2175))Br(Y(2175) --> phi f(0)(980))Br(f(0)(980) --> pi(+)pi(-)) = [3.23 +/- 0.75(stat) +/- 0.73(syst)] x 10^-4, assuming Y(2175) is a 1(--) state.
Conclusions:
- The observed structure is consistent with the Y(2175) resonance previously seen in e+e- initial-state radiation processes.
- This study provides evidence for the Y(2175) in J/psi decays, contributing to its understanding within the context of charmonium physics.
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