Related papers: Testing $\chi_c$ properties at BELLE II
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…
We search for the $e^+ e^- \to \gamma \chi_{bJ}$ ($J$ = 0, 1, 2) processes at center-of-mass energies $\sqrt{s}$ = 10.653, 10.701, 10.746, and 10.804 GeV. These data were collected with the Belle II detector at the SuperKEKB collider and…
Contributions from the reaction e+e- --> pi+pi- e+e- to the pion form factor measurement via radiative return method are discussed basing on the results of a Monte Carlo generator (EKHARA). The generator contains contributions from the…
The Monte Carlo generator EKHARA allows to simulate the process (e+e- to e+e-pi0) at energies of meson factories. We review the motivation, describe the current status of the generator, and discuss features, which will appear in the…
In this talk, we review the recent experimental developments on charmonium and charm spectroscopy base on the data samples taken by the BESIII, Belle, LHCb and CMS experiments. We concentrate on the resonant parameter measurement of…
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.…
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…
We report a new analysis of double charmonium production in e+ e- annihilation using a data sample collected by the Belle experiment. We confirm our previous observation of the processes e+ e- -> J/psi eta_c (chi_c0, eta_c(2S)) and perform…
Using a sample of 106 million $\psi(3686)$ decays, the branching fractions of $\psi(3686) \to \gamma \chi_{c0}, \psi(3686) \to \gamma \chi_{c1}$, and $\psi(3686) \to \gamma \chi_{c2}$ are measured with improved precision to be $(9.389 \pm…
A Monte Carlo generator (EKHARA) has been constructed to simulate the reaction e+e- -> pi+pi-e+e- based on initial and final state emission of a e+e- pair from e+e- -> pi+pi- production diagram.A detailed study of the process, as a…
The form factor of the electromagnetic excitation of $^{12}$C to its 2$^+_1$ state was measured at extremely low momentum transfers in an electron scattering experiment at the S-DALINAC. A combined analysis with the world form factor data…
We investigate the ${\cal O}(\alpha_s)$ correction to $e^+e^-\to J/\psi+\eta_{c2}$ in the NRQCD factorization approach. A detailed comparative study between $e^+e^-\to J/\psi+\eta_{c2}$ and $e^+e^-\to J/\psi+\chi^\prime_{c1}$ at $B$ factory…
We present the first analytic ${\cal O}(\alpha_s)$-computation at twist-$1$,$2$ of the $\bar B_{u,d,s} \to \gamma$ form factors within the framework of sum rules on the light-cone. These form factors describe the charged decay $\bar B_u \to…
With accumulation of high statistics data at BES and CLEO-c, many new interesting channels can get enough statistics for partial wave analysis (PWA). Among them, $\psi \to \gamma p\bar p, \gamma\Lambda\bar \Lambda, \gamma\Sigma \bar\Sigma,…
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…
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…
With the arrival of high luminosity B-factories like the Belle II experiment, $\tau$ decay measurements have become more precise than ever, allowing rarer processes to be explored, and finer details of $\tau$ decays to be studied. These are…
A factorization hypothesis is tested by examining a form factor of the $\omega\pi$ production in hadronic $B^0 \to D^{\ast \pm}\omega\pi^\mp$ decays. The form factor is compared to that from available $\tau$-lepton as well as $e^+e^-$ data…
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…
A short review of experimental and theoretical results on the large angle cross sections \gamma\gamma --> {two mesons} and the form factors \gamma*\gamma --> P={pi, \eta, \eta'} is given.