Observation of a resonance X(1835) in J / psi -> gamma pi+ pi- eta-prime
Aug, 20055 pages
Published in:
- Phys.Rev.Lett. 95 (2005) 262001
e-Print:
- hep-ex/0508025 [hep-ex]
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Abstract: (arXiv)
The decay channel J/\psi --> \gamma \pi^+ \pi^- \eta^{\prime} is analyzed using a sample of 5.8\times 10^7 J\psi events collected with the BESII detector. A resonance, the X(1835), is observed in the \pi^+ \pi^- \eta^{\prime} invariant mass spectrum with a statistical significance of 7.7 \sigma. A fit with a Breit-Wigner function yields a mass M = 1833.7 \pm 6.1(stat) \pm 2.7(syst) MeV/c^2, a width \Gamma = 67.7 \pm 20.3(stat) \pm 7.7(syst) MeV/c^2 and a product branching fraction B(J/\psi --> \gamma X) B(X --> \pi^+ \pi^- \eta^{\prime}) = (2.2 \pm 0.4(stat) \pm 0.4(syst)) \times 10^{-4}. The mass and width of the X(1835) are not compatible with any known meson resonance. Its properties are consistent with expectations for the state that produces the strong p\bar{p} mass threshold enhancement observed in the J\psi -->\gamma p \bar{p} process at BESII.- 13.75.Ev
- 12.39.Mk
- 12.40.Yx
- 13.20.Gd
- electron positron: colliding beams
- electron positron: annihilation
- J/psi(3100): electroproduction
- J/psi(3100): radiative decay
- mass spectrum: (eta(958) pi+ pi-)
- resonance: X(1830)
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