Related papers: $\eta'-g^*-g$ Transition Form Factor with Gluon Co…
I briefly review the formalism for treating the leading-twist two-gluon states appearing in processes which involve eta and eta' mesons. The constraints on the size of the lowest order Gegenbauer coefficients of the two-gluon distribution…
A phenomenological analysis of radiative $V\to P\gamma$ and $P\to V\gamma$ decays is performed with the purpose of determining the gluonic content of the $\eta$ and $\eta^\prime$ wave functions. Our results show that within our model there…
We argue that high-quality data on the reaction $e^+e^-\to \pi^+\pi^-\eta$ will allow one to determine the doubly-virtual form factor $\eta\to \gamma^*\gamma^*$ in a model-independent way with controlled accuracy. This is an important step…
We review our recent results for production of $\eta_c(1S)$ and $\eta_c(2S)$ in the $\gamma^* \gamma^* \to \eta_c(1S,2S)$ fusion and in proton-proton collisions via gluon-gluon fusion. The quarkonium wave functions are calculated by solving…
Using a continuum approach to the hadron bound-state problem, we calculate $\gamma^\ast \gamma \to \eta, \eta^\prime$ transition form factors on the entire domain of spacelike momenta, for comparison with existing experiments and in…
Using the CLEO~II detector, we have measured the differential cross sections for exclusive two-photon production of light pseudoscalar mesons $\pi^0$, $\eta$, and $\eta^{\prime}$. From our measurements we have obtained the form factors…
We present our model-independent and data-driven method to describe pseudoscalar meson transition form factors in the space- and (low-energy) time-like regions. The method is general and conforms a toolkit applicable to any other form…
The eta_c-gamma transition form factor is calculated within a perturbative approach. For the eta_c-meson, a wave function of the Bauer-Stech-Wirbel type is used where the two free parameters, namely the decay constant f(eta_c) and the…
We present the results of our recent analysis of the meson-photon transition form factors $F_{P\gamma}(Q^2)$ for the pseudoscalar mesons $P = \pi^0,\eta,\eta',\eta_c$, using the local-duality version of QCD sum rules.
The electromagnetic transition form factors of $\eta$ and $\eta'$ are calculated in the light-cone perturbation theory. We show that it is unreliable to determine the \eta-\etap'$ mixing angle without any additional normalization conditions…
The eta_c-gamma transition form factor is calculated in a model based on a modified hard scattering approach to exclusive reactions, in which transverse degrees of freedom are taken into account. For the eta_c-meson a distribution amplitude…
Power-suppressed corrections arising from end-point integration regions to the space-like vertex function of the massive eta'-meson virtual gluon transition eta' - g*g* are computed. Calculations are performed within the standard…
It has been realized for a long time that knowing the \eta and \eta' wave functions in terms of quark and gluon components probes our understanding of non-perturbative QCD dynamics. Great effort has been given to this challenge -- yet no…
The rare decays $\eta^{(\prime)}\to\ell^+\ell^-$, $\ell\in\{e,\mu\}$, are highly suppressed in the Standard Model, both by their chirality structure and the required loop attaching the lepton line to the $\eta^{(\prime)}\to\gamma^*\gamma^*$…
The mixing of $\eta-\eta'$ or $\eta-\eta'-G$ is of a great theoretical interest, because it concerns many aspects of the underlying dynamics and hadronic structure of pseudoscalar mesons and glueball. Determining the mixing parameters by…
One of the main goals of future electron-ion colliders is to improve our understanding of the structure of hadrons. In this letter, we study the exclusive $\eta_c$ production by $\gamma^{*} \gamma$ interactions in $eA$ collisions and…
In this paper, we study the transition form factors of the lightest pseudoscalar mesons, $\pi^0$, $\eta$, and $\eta'$, within the framework of resonance chiral theory. Our analysis is performed based on the data of time-like and space-like…
We discuss the effect of $\eta$--$\eta'$ mixing and of axial current anomalies on various decay processes. We describe the 2$\gamma$ decays of $\eta$ and $\eta'$, the radiative decays of low-lying vector mesons as well as the decays…
With a sample of $(10087\pm44)\times10^{6}$ $J/\psi$ events accumulated with the BESIII detector, we analyze the decays $\eta'\rightarrow\pi^+\pi^-l^+l^-(l=e,$ $\mu)$ via the process $J/\psi\rightarrow\gamma\eta'$. The branching fractions…
Using the CLEO II detector at CESR, we measure the eta' - gluon - gluon form-factor in Y(1S) decays. This form-factor especially at large eta' energies may provide an explanation of the large rate for B -> Xs eta'. Our data do not support a…