Related papers: Bjorken sum rule with analytic coupling at low Q2 …
The $Q^2$ evolution of polarised parton distributions at small $x$ is studied. Various analytic approximations are critically discussed. We compare the full evolution with that obtained from the leading-pole approximation to the splitting…
The generalized Gerasimov-Drell-Hearn (GDH) sum rule is known to be very sensitive to QCD radiative and power corrections. We improve the previously developed QCD-inspired model for the $Q^2$-dependence of the GDH sum rule. We take into…
A new analysis of baryon sum rules is done with modern values of parameters and known perturbative corrections. The restriction for gluon and quark condensates and the new value of nucleon coupling constant are found.
We discuss the possible target mass corrections in the QCD analysis of nucleon's spin-dependent structure functions measured in the polarized deep-inelastic leptoproduction. The target mass correction for the QCD Bjorken sum rule is…
The basis of renormalon calculus is briefly discussed. The method is applied to study QCD predictions for three sum rules of deep-inelastic scattering, namely for the Gross-Llewellyn Smith, Bjorken polarized and unpolarized sum rules. It is…
The QCD analytic running coupling alpha_{an} which has no nonphysical singularities for all Q^2>0 is considered for the initial perturbation theory approximations up to four loop order. The finiteness of the analytic coupling at zero is…
In this talk results from a new QCD analysis in leading (LO) and next--to--leading (NLO) order are presented. New parametrizations of the polarized quark and gluon densities are derived together with parametrizations of their fully…
The identity between expressions for the coefficient functions of the Bjorken and Ellis-Jaffe sum rules is derived in the conformal invariant limit of massless U(1) theory, namely in the perturbative quenched QED model, and in the same…
As is known from QED, a possible solution to the ghost-pole trouble can be obtained by imposing the $Q^2$-analyticity imperative. Here, the pole is compensated by the $\alpha$ non-analytic contribution that results in finite coupling…
A description of the generalized Gerasimov-Drell-Hearn sum rules for proton and neutron is suggested, using their relation to the Bjorken sum rule. The results support an earlier conjecture, that the structure function g_T features a smooth…
In the small $Q^2$ region, the sum rule for the polarized structure function $g_2$ corresponding to the moment at $n=0$ is derived. This sum rule shows that there is a tight connection among the resonances,the elastic and the continuum in…
This review article discusses the experimental and theoretical status of various Parton Model sum rules. The basis of the sum rules in perturbative QCD is discussed. Their use in extracting the value of the strong coupling constant is…
Two new sets of QCD sum rules for the nucleon axial coupling constants are derived using the external-field technique and generalized interpolating fields. An in-depth study of the predicative ability of these sum rules is carried out using…
We present skeleton-motivated evaluation of QCD observables. The approach can be applied in analytic versions of QCD in certain classes of renormalization schemes. We present two versions of analytic QCD which can be regarded as low-energy…
We discuss how the renormalisation scheme ambiguities in QCD can be fixed, when two observables are related, by requiring the coefficients in the perturbative expansion relating the two observables to have their conformal limit values, i.e.…
It is shown, that the possibility of a freezing of QCD running coupling constant at zero in the approach with "forced analyticity" can not be in accord with Schwinger-Dyson equation for gluon propagator. We propose to add to the analytic…
The generalized Baldin sum rule at finite four-momentum transfer Q^2 is evaluated utilizing a structure function parameterization fit to recent experimental data. The most recent measurements on F_1 from Hall C at Jlab, as well as the F_2…
We present the recent JLab measurements on moments of spin structure functions at intermediate and low Q^2. The Bjorken sum and Burkhardt-Cottingham sum on the neutron are presented. The later appears to hold. Higher moments (generalized…
An analytic ghost-free model for the QCD running coupling $\alpha(Q^2)$ is proposed. It is constructed from a more general approach we developed particularly for investigating physical observables of the type $F(Q^2)$ in regions that are…
A variant of QCD with the coupling suppressed in the infrared (IR) regime, as suggested by large-volume lattice calculations of the Landau-gauge gluon and ghost dressing functions, is considered. The coupling is further restricted by the…