Related papers: BELLE Data on the $\pi^0 \gamma* \gamma$ Form Fact…
The new data on the $\gamma^*\gamma \to \pi^0$ transition form factor of the Belle Collaboration are analyzed in comparison with those of BaBar (including the older data of CELLO and CLEO) using an approach based on light-cone sum rules.…
We perform a comparative theoretical study of the data at spacelike momentum transfer for the $\gamma^*\gamma\to\pi^0$ transition form factor, just reported by the Belle Collaboration, vs. those published before by BaBar, also including the…
The model of the $\chi_{c_i}-\gamma^*-\gamma^*$ and $\chi_{c_i}-J/\psi^*-\gamma^*$ form factors developed in [1] for $\chi_{c_1}$ and $\chi_{c_2}$ is extended to $\chi_{c_0}$ case. The studies performed within this model have shown that at…
The recent measured \gamma*\gamma \rightarrow \pi^0 transition form factor in the space-like region by the Belle Collaboration together with the previous published results by CLEO, CELLO and BABAR collaborations are analyzed using the…
The spin wave function of the f0(980)-meson is constructed under the assumption that the meson is dominantly a quark-antiquark state. This wave function is used in a calculation of the gamma* - f0 transition form factors. In the real-photon…
We study the transition form factor of $\pi^0\to\gamma^* \gamma$ as a function of the momentum transfer $Q^2$ within the light-front quark model (LFQM). We compare our result with the experimental data by BaBar as well as other calculations…
We discuss the impact of recent Belle data on our description of the pion transition form factor based on the assumption that a perturbative formalism and a nonperturbative one can be matched in a physically acceptable manner at a certain…
The photon transition form factors of $\pi$, $\eta$ and $\eta'$ are discussed in view of recent measurements. It is shown that the exact axial anomaly sum rule allows a precise comparison of all three form factors at high-$Q^2$ independent…
Implications of the recent new measurements of $B\to K_1\gamma$ by Belle are examined. It is shown that the new branching ratio $\calB(B\to K_1(1270)\gamma)$ requires very large form factor compared to the theoretically predicted one. This…
We present a recent treatment of the $\pi^0\gamma^\star\gamma$ transition form factor in the coupled Schwinger-Dyson and Bethe-Salpeter approach to stress the desirability of measuring it at CEBAF.
Belle data on gamma-gamma -> eta'-pi-pi are refitted using a broad J^{PC}=0^(-+) signal peaking in the mass range 2250-2300 MeV, but without \eta (1760). There is the possibility that this broad 0^(-+) signal may be identified with the…
Using the CLEO-II detector, we have measured the form factors associated with the electromagnetic transitions $\gamma^*\gamma \to $ meson. We have measured these form factors in the momentum transfer ranges from 1.5 to 9, 20, and 30 GeV^2…
It is noted that the low-energy behavior of the pion-photon transition form factor $F_{\pi\gamma}(Q^2)$ is sensitive to the transverse distribution of the pion wavefunction, and its high-energy behavior is sensitive to the longitudinal one.…
I discuss the progress in our theoretical understanding of the eta-gamma and eta'-gamma transition form factors, including the recent data from CLEO and L3 at large momentum transfer, Q^2. The experimental data above Q^2=1 GeV^2 can be well…
A dispersion integral is derived that connects data on $\eta\to \pi^+\pi^-\gamma$ to the $\eta\to \gamma\gamma^*$ transition form factor. A detailed analysis of the uncertainties is provided. We find for the slope of the $\eta$ transition…
We perform a dispersive analysis of the $\omega\pi$ electromagnetic transition form factor, using as input the discontinuity provided by unitarity below the $\omega\pi$ threshold and including for the first time experimental data on the…
We study the reaction e+e- --> e+e-pi0 and measure the gamma gamma* --> pi0 transition form factor in the momentum transfer range from 4 to 40 GeV^2. The analysis is based on 442 fb^-1 of integrated luminosity collected at PEP-II with the…
We discuss form factors and coupling constants for the $\gamma^* \pi^0 \gamma$, $\rho\pi\pi$ and $\gamma \pi \rho$ interactions generated by a model field theory that produces finite size $\bar{q}q$ meson modes. The approach implements…
The "handbag" model was proposed as an alternative, at the present day energies, to the leading term QCD predictions for some hard exclusive processes. The recent precise data from the Belle Collaboration on the large angle cross sections…
We report a measurement of the process gamma gamma* --> pi0 with a 759 fb^{-1} data sample recorded with the Belle detector at the KEKB asymmetric-energy e+e- collider. The pion transition form factor, F(Q^2), is measured for the…