Analysis of the J/psi --> pi^0 gamma^* transition form factor

Abstract

In view of the first measurement of the branching fraction for J/psi --> pi^0 e^+ e^- by the BESIII collaboration, we analyze what can be learnt on the corresponding transition form factor using dispersion theory. We show that light-quark degrees of freedom dominate the spectral function, in particular two-pion intermediate states. Estimating the effects of multi-pion states as well as charmonium, we arrive at a prediction for the complete form factor that should be scrutinized experimentally in the future.

6 pages, 3 figures; v2 matches version published in Phys. Rev. D

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Cited by in corpus (7)

• Analysis of rescattering effects in $3\pi$ final states
• Effective-Lagrangian study of ${\psi }^{\prime }(J/\psi )\to VP$ and the insights into $\rho \pi$ puzzle
• Khuri-Treiman analysis of $J/\psi \to {\pi }^{+}{\pi }^{-}{\pi }^0$
• Study of the electromagnetic Dalitz decay $J/\psi \to e^{+}{e}^{-}{\pi }^0$
• Correlations of $C$ and $CP$ violation in $\eta \to {\pi }^0{\ell }^{+}{\ell }^{-}$ and ${\eta }^{\prime }\to \eta {\ell }^{+}{\ell }^{-}$
• QCD analysis of the $P$-wave charmonium electromagnetic Dalitz decays $h_c\to {\eta }^{(\prime )}{\ell }^{+}{\ell }^{-}$
• Dispersive analysis of the $J/\psi \to {\pi }^0{\gamma }^{\ast }$ transition form factor with $\rho$-$\omega$ mixing effects