Evidence for a J/psi-ppbar Pauli Strong Coupling ?

Abstract

The couplings of charmonia and charmonium hybrids (generically Psi) to ppbar are of great interest in view of future plans to study these states using an antiproton storage ring at GSI. These low to moderate energy Psi-ppbar couplings are not well understood theoretically, and currently must be determined from experiment. In this letter we note that the two independent Dirac (gamma_mu) and Pauli (sigma_munu) ppbar couplings of the J/psi and psi' can be constrained by the angular distribution of e+e- -> (J/psi, psi') -> ppbar on resonance. A comparison of our theoretical results to recent unpolarized data allows estimates of the ppbar couplings; in the better determined J/psi case the data is inconsistent with a pure Dirac (gamma_mu) coupling, and can be explained by the presence of a sigma_munu term. This Pauli coupling may significantly affect the cross section of the PANDA process p pbar -> pi0 J/psi near threshold. There is a phase ambiguity that makes it impossible to uniquely determine the magnitudes and relative phase of the Dirac and Pauli couplings from the unpolarized angular distributions alone; we show in detail how this can be resolved through a study of the polarized reactions.

7 pages, 7 figures. v2 generalizes v1 to complex J/psi-ppbar couplings

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• Charmonium production in p pbar annihilation: Estimating cross sections from decay widths
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• Measurements of J/psi --> p \bar{p}
• Associated Charmonium Production in Low Energy p-pbar Annihilation
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Cited by in corpus (10)

• Production of X(3872) at PANDA
• Revisiting the production of charmonium plus a light meson at PANDA
• Meson Emission Model of Psi to N Nbar m Charmonium Strong Decays
• Implication of the observed $\psi (3770)\to p\bar{p}{\pi }^0$ for studying the $p\bar{p}\to \psi (3770){\pi }^0$ process
• Production of the charmoniumlike state $Y(4220)$ through the $p\bar{p}\to Y(4220){\pi }^0$ reaction
• Resonances contribution to two-photon exchange effects and possible large forward-backward asymmetry in $e^{+}{e}^{-}\to p\bar{p}$
• Branching fractions for chi_cJ -> p p-bar pi^0, p p-bar eta, and p p-bar omega
• Role of the low-lying nucleon resonances in the $p\bar{p}\to \psi \eta$ reaction
• Rescattering effects in antiproton-induced exclusive $J/\psi$ and ${\psi }^{\prime }$ production on the deuteron
• Psi to N Nbar m