$J/\psi \to \gamma {\eta }^{\prime }{\pi }^{+}{\pi }^{-}$ and the structure observed around the $\bar{p}p$ threshold

Abstract

We analyze the origin of the structure observed in the reaction $J/\psi \to \gamma {\eta }^{\prime }{\pi }^{+}{\pi }^{-}$ for ${\eta }^{\prime }{\pi }^{+}{\pi }^{-}$ invariant masses close to the antiproton-proton ($\bar{p}p$) threshold, commonly associated with the $X(1835)$ resonance. Specifically, we explore the effect of a possible contribution from the two-step process $J/\psi \to \gamma \bar{N}N\to \gamma {\eta }^{\prime }{\pi }^{+}{\pi }^{-}$. The calculation is performed in distorted-wave Born approximation which allows an appropriate inclusion of the $\bar{N}N$ interaction in the transition amplitude. The $\bar{N}N$ amplitude itself is generated from a corresponding potential recently derived within chiral effective field theory. We are able to reproduce the measured spectra for the reactions $J/\psi \to \gamma \bar{p}p$ and $J/\psi \to \gamma {\eta }^{\prime }{\pi }^{+}{\pi }^{-}$ for invariant masses around the $\bar{p}p$ threshold. The structure seen in the ${\eta }^{\prime }{\pi }^{+}{\pi }^{-}$ spectrum emerges as a threshold effect due to the opening of the $\bar{p}p$ channel.

arXiv comment9 pages, 5 figures

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Cited by in corpus (8)

• A Review on Partial-wave Dynamics with Chiral Effective Field Theory and Dispersion Relation
• Pole analysis on the hadron spectroscopy of ${\Lambda }_b\to J/\Psi p{K}^{-}$
• Semileptonic $B$ and $B_s$ decays involving scalar and axial-vector mesons
• A comprehensive study on the semileptonic decay of heavy flavor mesons
• New insights into the oscillation of the nucleon electromagnetic form factors
• Invariant-mass spectrum of $\Lambda \bar{\Lambda }$ pair in the process $e^{+}{e}^{-}\to \varphi \Lambda \bar{\Lambda }$
• Structure around $p\bar{p}$ threshold in $J/\psi$ radiative decays
• Reexamination of antinucleon-nucleon interactions in covariant chiral effective field theory