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We prove that Pade approximants yield increasingly accurate predictions of higher-order coefficients in QCD perturbation series whose high-order behaviour is governed by a renormalon. We also prove that this convergence is accelerated if…
We present details of study of the Bjorken polarized sum rule carried out recently in [1] within the range of energies where the data were collected by JLAB collaboration, 0.05 GeV2 < Q2 < 3 GeV2. Three approaches to QCD with analytic…
We present a NLO perturbative analysis of all available data on the polarized structure function g_1(x,Q^2) with the aim of making a quantitative test of the validity of the Bjorken sum rule, of measuring \alpha_s, and of deriving helicity…
Results of applying analytic perturbation theory (APT) to the Bjorken sum rule are presented. We study the third-order QCD correction within the analytic approach and investigate its renormalization scheme dependence. We demonstrate that,…
We present in detail a new systematic method which can be used to automatically eliminate the renormalization scheme and scale ambiguities in perturbative QCD predictions at all orders. We show that all of the nonconformal \beta-dependent…
We have extracted QCD matrix elements from our data on double polarized inelastic scattering of electrons on nuclei. We find the higher twist matrix element \tilde{d_2}, which arises strictly from quark- gluon interactions, to be…
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…
We present recent results on the Bjorken and the generalized forward spin polarizability sum rules from Jefferson Lab Hall A and CLAS experiments, focusing on the low $Q^2$ part of the measurements. We then discuss the comparison of these…
The power correction, surviving the zero quark mass limit and found earlier to restore the validity of Burkhardt-Cottingham sum rule, provides the contribution to the Bjorken sum rule as well. The leading perturbative correction to the…
We consider heavy quark contributions to the polarized Bjorken sum rule. We found good agreement between the experimental data and the predictions of analytic QCD. To satisfy the limit of photoproduction, we use new representation of the…
We present the estimates of the order $O(\alpha^{4}_{s})$ QCD corrections to $R(s)$, $R_{\tau}$ and to the deep-inelastic scattering sum rules, namely to the non-polarized and polarized Bjorken sum rules and to the Gross-Llewellyn Smith sum…
We have discovered 7 intimate connections between the published results for the radiative corrections, $\Ck$, to the Gross--Llewellyn Smith (GLS) sum rule, in deep-inelastic lepton scattering, and the radiative corrections, $\Cr$, to the…
Infrared renormalons and $1/Q^2$ power corrections in deep-inelastic sum rules are studied. The renormalization of operators with power divergence are discussed. The higher-twist terms in the operator product expansion are shown to account…
We investigate the Gross-Llewellyn Smith sum rule within the framework of analytic QCD. A comparison is performed between experimental data, lattice calculations, and perturbative QCD based on conventional and analytic versions of…
We clarify conflicting results in the literature on coefficient functions in front of higher twist operators contributing to the parton sum rules for deep inelastic scattering from polarized targets. The necessary corrections do not affect…
The zero to four loop contribution to the cross section $R_{e^{+}e^{-}}$ for $e^{+}e^{-} \longrightarrow$ hadrons, when combined with the renormalization group equation, allows for summation of all leading-log ($LL$), next-to-leading-log…
We present the attempt to study the problem of the estimates of higher-order perturbative corrections to physical quantities in the Euclidean region. Our considerations are based on the application of the scheme-invariant methods, namely…
We show how to fix the renormalization scale for hard-scattering exclusive processes such as deeply virtual meson electroproduction by applying the BLM prescription to the imaginary part of the scattering amplitude and employing a fixed-t…
We propose a renormalon-inspired resummation of QCD perturbation theory based on approximating the renormalization scheme (RS) invariant effective charge beta-function coefficients by the portion containing the highest power of…
Previously developed Pade-related method of resummation for QCD observables, which achieves exact renormalization-scale-invariance, is extended so that the scheme-invariance is obtained as well. The dependence on the leading scheme…