Spin-parity analysis of $p\bar{p}$ mass threshold structure in $J/\psi$ and $\psi (3686)$ radiative decays

Abstract
A partial wave analysis of the $p\bar{p}$ mass-threshold enhancement in the reaction $J/\psi\rightarrow\gamma p\bar{p}$ is used to determine its $J^\text{PC}$ quantum numbers to be $0^{-+}$, its peak mass to be below threshold at $M=1832_{-5}^{+19}(\text{stat})_{-17}^{+18}(\text{syst})±19(\text{model})$ $\text{MeV}/c^2$, and its total width to be $\Gamma <76$ $\text{MeV}/c^2$ at the 90% C.L. The product of branching ratios is measured to be $\text{BR}[J/\psi\rightarrow\gamma X(p\bar{p})]$ $\text{BR}[X(p\bar{p})\rightarrow p\bar{p}]=[9.0_{-1.1}^{+0.4}(\text{stat})_{-5.0}^{+1.5}(\text{syst})±2.3(\text{model})]×10^{-5}$. A similar analysis performed on $\psi (3686)\rightarrow\gamma p\bar{p}$ decays shows, for the first time, the presence of a corresponding enhancement with a production rate relative to that for $J/\psi$ decays of $R=[5.08_{-0.45}^{+0.71}(\text{stat})_{-3.58}^{+0.67}(\text{syst}) ±0.12(\text{model})]%$.
Description
Keywords
Branching ratio, Partial wave analysis, Production rates, Quantum numbers, Radiative decay, Similar analysis, Atomic physics, Physics, Quantum theory
Citation
Ablikim, M., Achasov, M. N., Alberto, D., Ambrose, D. J., An, F. F., An, Q., . . . Zuo, J. X. (2012). Spin-parity analysis of $p\bar{p}$ mass threshold structure in $J/\psi$ and $\psi (3686)$ radiative decays. Physical Review Letters, 108(11), 112003. http://dx.doi.org/10.1103/PhysRevLett.108.112003
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© 2012 American Physical Society.
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Article