Observation of the Anomalous Shape of $X(1840)$ in $J/\psi \to \gamma 3({\pi }^{+}{\pi }^{-})$ Indicating a Second Resonance Near $p\bar{p}$ Threshold

Abstract

Using a sample of $(10087\pm 44)\times 10^6$ $J/\psi$ events, which is about 45 times larger than that was previously analyzed, a further investigation on the $J/\psi \to \gamma 3({\pi }^{+}{\pi }^{-})$ decay is performed. A significant distortion at 1.84 GeV/$c^2$ in the line-shape of the $3({\pi }^{+}{\pi }^{-})$ invariant mass spectrum is observed for the first time, which could be resolved by two overlapping resonant structures, $X(1840)$ and $X(1880)$. The new state $X(1880)$ is observed with a statistical significance larger than $10\sigma$. The mass and width of $X(1880)$ are determined to be $1882.1\pm 1.7\pm 0.7$ MeV/$c^2$ and $30.7\pm 5.5\pm 2.4$ MeV, respectively, which indicates the existence of a $p\bar{p}$ bound state.

References in corpus (23)

• Design and Construction of the BESIII Detector
• Coherent Exclusive Exponentiation For Precision Monte Carlo Calculations
• Observation of a near-threshold enhancement in th p pbar mass spectrum from radiative J/psi-->gamma p pbar decays
• Method for detector description transformation to Unity and application in BESIII
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• Observation of a resonance X(1835) in J/ψ--> γπ^+ π^- η^{\prime}
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• Spin-Parity Analysis of ppbar Mass Threshold Structure in J/psi and psi' Radiative Decays
• X(1835) as the Lowest Mass Pseudoscalar Glueball and Proton Spin Problem
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• Observation of a ppb mass threshoud enhancement in ψ^\prime\toπ^+π^-J/ψ(J/ψ\toγp\bar{p}) decay
• A possible 0^{-+} glueball candidate X(1835)
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• On the structure of the X(1835) baryonium
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• Observation of a structure at 1.84 GeV/c${}^2$ in the $3({\pi }^{+}{\pi }^{-})$ mass spectrum in $J/\psi \to \gamma 3({\pi }^{+}{\pi }^{-})$ decays
• A possible mechanism for producing the threshold enhancement in $J/\psi \to \gamma p\bar{p}$

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