English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The electromagnetic Dalitz decays$J/\psi\rightarrow\eta^{(\prime)}e^{+}e^{-}$ with large recoil momentum arestudied in the framework of perturbative QCD. Meanwhile, the soft contributionsfrom the small recoil momentum region are described by the overlap of soft wavefunctions, and the resonance contributions are estimated by the vector mesondominance model. Based on this dynamical picture, the transition form factors$f_{\psi\eta^{(\prime)}}(q^{2})$ in full kinematic region are calculated forthe first time, and we find that the transition form factors are insensitive tothe shapes of $\eta^{(\prime)}$ distribution amplitudes. Our prediction of thenormalized transition form factor $F_{\psi \eta}(q^{2})\equivf_{\psi\eta}(q^{2})/f_{\psi\eta}(0)$ agrees well with its experimental data. Inaddition, we also find that the branching ratios$\mathcal{B}(J/\psi\rightarrow\eta^{(\prime)}e^{+}e^{-})$ are dominated by thecontributions of perturbative QCD, and the resonance contributions arenegligibly small as well as the soft contributions due to the suppression ofthe kinematic factor. With all these contributions, our results of thebranching ratios $\mathcal{B}(J/\psi\rightarrow\eta^{(\prime)}e^{+}e^{-})$ andthe ratio $R_{J/\psi}^{e}=\mathcal{B}(J/\psi\rightarrow\etae^{+}e^{-})/\mathcal{B}(J/\psi\rightarrow\eta^{\prime}e^{+}e^{-})$ are in goodagreement with their experimental data. Using the obtained $F_{\psi\eta^{(\prime)}}(q^{2})$, we give the predictions of the branching ratios$\mathcal{B}(J/\psi\rightarrow\eta^{(\prime)}\mu^{+}\mu^{-})$ and their ratio$R_{J/\psi}^{\mu}$.

QCD analysis of electromagnetic Dalitz decays $J/\psi\rightarrow\eta^{(\prime)}\ell^{+}\ell^{-}$