相关论文: gamma^* gamma^* -> pi^0 Form Factor from AdS/QCD
The holographic QCD prediction for the pion distribution amplitude (DA) $\phi_{hol}(u)$ is used to compute the pion spacelike electromagnetic form factor $F_{\pi}(Q^2)$ within the QCD light-cone sum rule method. In calculations the pion's…
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 formfactors of B_1 -> pi and D_1 -> pi transitions, where B_1(D_1) is the 1^+ P-wave -> Q gamma_{\nu}\gamma_5q meson state, are calculated in the framework of the light cone QCD. Furthermore these formfactors are compared with the pole…
We reconsider QCD factorization for the leading power contribution to the $\gamma^{\ast} \gamma \to \pi^0$ form factor $F_{\gamma^{\ast} \gamma \to \pi^0} (Q^2)$ at one loop using the evanescent operator approach, and demonstrate the…
We investigate semileptonic form factors of $D_{(s)}$ meson from a modified soft-wall 4-flavor holographic model. The model successfully reproduces the masses and decay constants of various mesons, including $\rho$, $K^*$, $D^*$, $D_s^*$,…
A state-of-the-art analysis of the pion-photon transition form factor is presented based on an improved theoretical calculation that includes the effect of a finite virtuality of the quasi-real photon in the method of light-cone sum rules.…
We study pion in the holographic model of Hirn and Sanz which contains two Yang-Mills fields defined in the background of the sliced AdS space. The infrared boundary conditions imposed on these fields generate the spontaneous breaking of…
An analysis of all available data (CELLO, CLEO, \babar) in the range $[1\div 40]$ GeV$^2$ for the pion-photon transition form factor in terms of light-cone sum rules with next-to-leading-order accuracy is discussed, including twist-four…
We investigate the possibility to constrain the pion distribution amplitude from the gamma* gamma* -> pi transition. For a surprisingly large range in the two photon virtualities we find that the transition form factor is essentially…
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 work, we propose a method to compute the gravitational form factor $D(Q^2)$ in holographic QCD by exploiting the remarkable correspondence between semi-classical light-front QCD and semi-classical field theories in wrapped spacetime…
We discuss the status of the pion distribution amplitude (DA) in connection with QCD sum rules and experimental data on the $\gamma^*\gamma^\to \pi^0$ transition form factor. Contents: (a) Pion DA in generalized QCD Sum Rules (SRs); (b)…
The recent BaBar measurements of the $\gamma\gamma^{*}\to \pi^{0}$ transition form factor show spectacular deviation from perturbative QCD prediction for large space-like $Q^{2}$ up to $34\,\rm GeV^{2}$. When plotted against $Q^{2}$,…
We calculate gravitational form factors of vector mesons using a holographic model of QCD. These provide restrictions on the generalized parton distributions of vector mesons, via the sum rules connecting stress tensor form factors to GPDs.…
We investigate the interactions among the pion, vector mesons and external gauge fields in the holographic dual of massless QCD proposed in a previous paper, hep-th/0412141, on the basis of probe D8-branes embedded in a D4-brane background…
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…
A possibility of KLOE-2 experiment to measure the width Gamma(pi0 to gamma gamma) and the (pi0 gamma gamma*) form factor F(Q^2) at low invariant masses of the virtual photon in the space-like region is considered. This measurement is an…
Confronted with some surprising claims about experimentally measured or theoretically expected dependencies on the involved momentum transfer of various form factors of pseudoscalar mesons, we reassess the present status of these quantities…
We consider the subleading contributions of the hadronic vacuum polarization, involving the $\pi^0\gamma^*\gamma^*$ transition form factor, to the muon anomalous magnetic moment $g-2$. Various models for the form factor, based on hadronic…
To realize massive pions, we study variations of the holographic model of massless QCD using the D4/D8/anti-D8 brane configuration proposed by Sakai and Sugimoto. We propose deformations which break the chiral symmetry explicitly and…