Related papers: Pion form factor and QCD sum rules: case of pseudo…
Nonperturbative Wilson coefficients associated with the leading chiral-symmetry-breaking operators in the operator product expansion of the pseudoscalar QCD correlation function are derived. Implementation of the new, instanton-induced…
Light-cone sum rules have proved to be very useful in calculating hadronic matrix elements for exclusive processes. I present recent applications of this method to the pion electromagnetic form factor and to the form factors of $\gamma^*…
We derive a novel model-independent result for the pion susceptibility in QCD via the isovector-pseudoscalar vacuum polarisation. In the neighbourhood of the chiral-limit, the pion susceptibility can be expressed as a sum of two independent…
We perform a QCD sum rule analysis for the $f_0$ light tetraquark taking into account the contribution arising from the two pion intermediate state. With the interpolating currents of the different chiral combinations of scalar and…
The method of light-cone QCD sum rules is applied to the calculation of the form factors of $\gamma^*\rho \to \pi$ and $\gamma^*\gamma \to \pi^0$ transitions. We consider the dispersion relation for the $\gamma^*(Q^2)\gamma^*(q^2) \to…
We review a nonlocal-condensate approach and its application in QCD sum rules for the spacelike electromagnetic pion form factor. It is shown that the nonlocality of the condensates is a key point to include nonperturbative contributions to…
We use the method of QCD sum rules in the presence of an external pion field to investigate isospin symmetry breakings in pion-nucleon couplings. Possible manifestations of such isospin symmetry breaking are examined in the context of…
We present an extension of the QCD sum rule method in the external fields so as to determine the induced pseudoscalar coupling constant g_P, which tests the validity of the partially conserved axial current (PCAC) hypothesis. This is…
In this paper we calculate the power corrections to the pion transition form factor within the framework of perturbative QCD approach on the basis of $k_T$ factorization. The power suppressed contributions from higher twist pion wave…
We report a calculation of the nucleon axial form factors $G_A^q(Q^2)$ and $G_P^q(Q^2)$ for all three light quark flavors $q\in\{u,d,s\}$ in the range $0\leq Q^2\lesssim 1.2\text{ GeV}^2$ using lattice QCD. This work was done using a single…
The extrapolation of nucleon magnetic form factors calculated within lattice QCD is investigated within a framework based upon heavy baryon chiral effective-field theory. All one-loop graphs are considered at arbitrary momentum transfer and…
We develop a QCD sum rule analysis of the form factor $F_{\gamma^*\gamma^*\pi^0}(q^2,Q^2)$ in the region where virtuality of one of the spacelike photons is small $q^2 \ll 1 GeV^2$ while another is large: $Q^2 \gapprox 1 GeV^2$. We…
The pion electromagnetic form factor F_{\pi}(Q^{2}) is calculated at the leading order of pQCD using the running coupling constant (\alpha_{S}(Q^{2}(1-x)(1-y))) approach. The resummed expression for F_{\pi}(Q^{2}) is found. It is shown that…
We analyze new QCD sum rules for the pion wave function $\phi_{\pi}(x)$, obtained recently by A.V. Radyushkin in the framework of the non-local vacuum condensates method for non-diagonal correlators, and suggest a new approach for…
We consider finite volume effects on the electromagnetic form factor of the pion. We compute the peudoscalar-vector-pseudoscalar correlator in the $\epsilon$ expansion of chiral perturbation theory up to the next-to-leading order and find a…
Using the approach based on conformal symmetry we calculate the two-loop coefficient function for the axial-vector contributions to two-photon processes in the $\overline{\rm MS}$ scheme. This is the last missing element for the complete…
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…
In this paper we study QCD and power corrections to sum rules which show up in deep inelastic lepton-hadron scattering. Furthermore we will make a distinction between fundamental sum rules which can be derived from quantum field theory and…
We reinvestigate the QCD sum rule for the pi NN coupling constant, g, starting from the vacuum-to-pion matrix element of the correlation function of the interpolating fields of two nucleons. We study in detail the physical content of the…
The form-factors for the transition $ N^*(1535)\to N $ induced by isovector and isoscalar axial currents within the framework of light-cone QCD sum rules by using the most general form of the interpolating current are calculated. In…