Related papers: The $\gamma^* \gamma^*\to\eta_c$ transition form f…
We evaluate the light-quark meson contributions to three exact light-by-light scattering sum rules in light of new data by the Belle Collaboration, which recently has extracted the transition form factors of the tensor meson $f_2(1270)$ as…
We investigate the form factors for pseudoscalar-meson-photon transitions by means of dispersive QCD sum rules and demonstrate that most of the measurements done so far (in particular, those by BaBar for $\eta,$ $\eta',$ and $\eta_c$ and…
The low $Q^2$ slopes of the the transition form factors provide a unique method to measure the sizes of the neutral pseudo-scalar mesons, since they do not have electromagnetic form factors. From the slope one obtains the "axial transition…
It has been pointed out that the recent BaBar data on the pi gamma^* -> gamma transition form factor F_{pi gamma}(Q^2) at low (high) momentum transfer squared Q^2 indicate an asymptotic (flat) pion distribution amplitude. These seemingly…
We study the pion-photon transition form factor (TFF) $F^{\gamma*\gamma\pi^0}(Q^2)$ using a state-of-the art implementation of light cone sum rules (LCSRs) within fixed-order QCD perturbation theory. The spectral density in the dispersion…
We calculate the transition form factor for the 'B_c -> B_u^* gamma' decay taking into account only the short distance contribution, in framework of QCD sum rules method. We observe that the transition form factor predicted by the QCD sum…
We present the results on the ratios $E_{1+}^{(3/2)}/M_{1+}^{(3/2)}$ and $S_{1+}^{(3/2)}/M_{1+}^{(3/2)}$ for the $\gamma^* N \to \Delta(1232)$ transition at $Q^2\leq 4 (GeV/c)^2$ extracted from the $p(e,e'p)\pi^0$ cross section using two…
It is shown that the pi^0 transition form factor F(Q_1^2,Q_2^2) differs substantially from its one-real-photon limit F(Q_1^2,0) even for rather small values of Q_2^2 (approx 0.1 GeV^2), which cannot be excluded in experiments with one…
Relativistic integral representation in terms of experimental neutron-proton scattering phase shifts alone is used to compute the charge form factor of the deuteron $G_{Cd}(Q^2)$. The results of numerical calculations of $|G_{Cd}(Q^2)|$ are…
We reanalyze the $\gamma\gamma^{*} \to \pi^{0}$ transition form factor $F_{\pi\gamma}(Q^2)$ within the QCD light-cone sum rules method with the twist-4 accuracy. In computations the pion leading twist distribution amplitude (DA) with two…
In this article, we calculate the vector form factors $f^+_{K\pi}(Q^2)$ and $f^-_{K\pi}(Q^2)$ within the framework of the light-cone QCD sum rules approach. The numerical values of the $f^+_{K\pi}(Q^2)$ are compatible with the existing…
We predict contributions of higher $K$-resonances to the radiative rare decays $b\to s\gamma$, in the framework of the QCD sum rules on the light cone, which combines the traditional QCD sum rule method with the description of final state…
We continue our work on the light-front formulation of quarkonium $\gamma^* \gamma$ transition form factors, extending the formalism to $J^{PC} = 2^{++}$ tensor meson states. We present an analysis of $\gamma^* \gamma \to \chi_{c2}$…
The $B\to D$ transition form factor (TFF) $f^{B\to D}_+(q^2)$ is determined mainly by the $D$-meson leading-twist distribution amplitude (DA) , $\phi_{2;D}$, if the proper chiral current correlation function is adopted within the light-cone…
We make a detailed study on the typical production channel of double charmoniums, $e^+e^-\to J/\psi+\eta_c$, at the center-of-mass collision energy $\sqrt{s}=10.58$ GeV. The key component of the process is the form factor $F_{\rm VP}(q^2)$,…
Within the framework of nonrelativistic QCD (NRQCD) factorization formalism, we compute the helicity amplitude as well as the decay width of $\eta_{Q2}$ ($Q=c,b$) electromagnetic decay into two photons up to next-to-next-to-leading order…
Corrections due to gluon condensate to electromagnetic form factors of the transition $\pi+\gamma^* \to A_1$ are calculated by standard QCD sum rules technique. The obtained results are compared to the corresponding light-cone QCD sum…
We present a calculation of $P\to \gamma^{(\ast)}\gamma^{(\ast)}$ processes, where $P=\pi^0,\ \eta,\ \eta'$, at the one-loop level up to and including next-to-next-to-leading order (NNLO) in large-$N_c$ chiral perturbation theory. The…
QCD analysis of F_2^{\gamma}(x,Q^2) is revisited. It is emphasized that the presence of the inhomogeneous term in the evolution equations for quark distribution functions of the photon implies important difference in the way factorization…
Using the results on the electromagnetic pion Form Factor (FF) obtained in the $O(\alpha_s)$ QCD sum rules with non-local condensates \cite{BPS09} we determine the effective continuum threshold for the local duality approach. Then we apply…