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A. L. Kataev

Publications and source records attributed to A. L. Kataev.

At least 73 records · Page 4Linked to original sources
arXiv2007

Fixation of theoretical ambiguities in the improved fits to $xF_3$ CCFR data at the next-to-next-to-leading order and beyond

Using the results for the NNLO QCD corrections to anomalous dimensions of odd $xF_3$ Mellin moments and N$^3$LO corrections to their coefficient functions we improve our previous analysis of the CCFR'97 data for $xF_3$. The possibility of extracting from the fits of $1/Q^2$-corrections is analysed using three independent models,including infrared renormalon one. Theoretical quetion of applicability of the renormalon-type inspired large-$β_0$ approximation for estimating corrections to the coefficient functions of odd $xF_3$ and even non-singlet $F_2$ moments are considered. The comparison with [1/1] Padé estimates is given. The obtained NLO and NNLO values of $α_s(M_Z)$ are supporting the results of our less definite previous analysis and are in agreement with the world average value $α_s(M_Z)\approx 0.118$. We also present first N$^3$LO extraction of $α_s(M_Z)$. The interplay between higher-order perturbative QCD corrections and $1/Q^2$-terms is demonstrated. The results of our studies are compared with those obtained recently using the NNLO model of the kernel of DGLAP equation and with the results of the NNLO fits to CCFR'97 $xF_3$ data, performed by the Bernstein polynomial technique.

hep-ph↗
arXiv2006

New relations between DIS sum rules

New relations between Bjorken polarized, Gross-Llewellyn Smith and Bjorken unpolarized sum rules are proposed. They are based on the ``universality'' of the perturbative and non-perturbative $\rm{1/Q^2}$ contributions to these sum rules. The letter facts can be deduced from the corresponding renormalon calculations. The similarity of $\rm{1/Q^2}$ corrections are checked by inspecting the numerical results obtained within several approaches.The discussed relations are in agreement with existing experimental data.Some possible new phenomenological applications are mentioned including estimates of not yet measured Bjorken unpolarized sum rule.

hep-ph↗
arXiv2006

Reconsidered estimates of the 10th order QED contributions to the muon anomaly

The problem of estimating the 10th order QED corrections to the muon anomalous magnetic moment is reconsidered. The incorporation of the recently improved contributions to the $α^4$ and $α^5$- corrections to $a_μ$ within the renormalization-group inspired scheme-invariant approach leads to the estimate $a_μ^{(10)}\approx 643(α/pi)^5$. It is in good agreement with the estimate $a_μ^{(10)}= 663(20) (α/π)^5$, obtained by Kinoshita and Nio from the numerical calculations of 2958 10-th order diagrams, which are considered to be more important than the still uncalculated 6122 10th-order $m_μ/m_e$-dependent vertex graphs, and 12672 5-loop diagrams, responsible for the mass-independent constant contribution both to $a_μ$ and $a_e$. This confirms Kinoshita and Nio guess about dominance of the 10-th order diagrams calculated by them. Comparisons with other estimates of the $α^5$- contributions to $a_μ$, which exist in the literature, are presented.

hep-ph↗
arXiv2006

The Comments on QED Contributions to $(g-2)_μ$

The comparison of definite numerical values of analytically evaluated asymptotic expressions for order $α^4$ and $α^5$ QED contributions to the muon anomalous magnetic moment with the results of numerical calculations are presented. It is stressed that observed agreement can be considered as the additional argument in favour of correctness of the recent direct numerical calculations.

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arXiv2005

The relations between Bjorken polarized, Bjorken unpolarized and Gross--Llewellyn Smith sum rules

New relations between Bjorken polarized, Bjorken unpolarized and Gross-Llewellyn Smith sum rules are desribed. These relations are valid in the region, where both perturbative series and the series in power-suppressed $1/Q^2$-terms do not yet mahifest the features of asymptotic expansions. The experimentally based considerations support these relations which may surve as the guide for possible in future measurements of the Bjorken unpolarized sum rule at Neutrino Factories.

hep-ph↗
arXiv2005

Renormalons at the boundaries between perturbative and non-perturbative QCD

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 shown that the renormalon structures of theses sum rules are closely related. These properties are giving us the hint that theoretical expressions of these three sum rules are similar both in the and non-perturbative sectors. Some phenomenological consequances of the new relations are discussed.

hep-ph↗
arXiv2005

Infrared renormalons and the relations between the Gross-Llewellyn Smith and the Bjorken polarized and unpolarized sum rules

It is demonstrated that the infrared renormalon calculus indicates that the QCD theoretical expressions for the Gross-Llewelln Smith sum rules and for the Bjorken polarized and unpolarized ones contain an identical negative twist-4 1/Q^2 correction. This observation is supported by the consideration of the results of calculations of the corresponding twist-4 matrix elements. Together with the indication of the similarity of perturbative QCD corrections to these three sum rules, this observation leads to simple new theoretical relations between the Gross-Llewellyn Smith and Bjorken polarized and unpolarized sum rules in the energy region $Q^2\geq 1 GeV^2$. The validity of this relation is checked using concrete experimental data for the Gross-Llewellyn Smith and Bjorken polarized sum rules

hep-ph↗
arXiv2005

Evaluation of the isospin asymmetry of the nucleon structure functions with CLAS++

The possibility to estimate the isospin symmetry breaking effects in the non-perturbative part of F_2 structure function of the chargeg lN deep-pnelastic scattering, which will provide CLAS++ dewtector of the upgraded TJNAF machine at $Q^2\approx 2 GeV^2$, is discussed. The problems of the Gottfried sum rule extraction are also considered.

hep-ph↗
arXiv2004

The puzzle of the non-planar structure of the QCD contributions to the Gottfried sum rule

The recent finding, that in QCD at the $O(α_s^2)$-level only non-planar diagrams, which are suppressed by a factor $1/N_c^2$ relative to planar ones, are contributing to the valence part of the Gottfried sum rule, is described. To our knowledge, this intriguing unique feature did not manifest itself previously in any perturbative expansion of any gauge quantum field model. We hope that this discovery may have some theoretical explanation.

hep-ph↗
arXiv2004

QCD sum rules and radial excitaions of light pseudoscalar and scalar mesons

The calculations of masses and decay constants of the radial excitations of light pseudoscalar and scalar mesons within QCD sum rules method are briefly reviewed. The predictions are based on the $1/N_c$-supported model spectra, which consist of infinite number of infinitely narrow resonances, and on the assumption that the ground states of light scalar mesons may be considered as the $\bar{q}q$-bound states. The results of the studies are compared with the existing experimental data and with the predictions of other theoretical approaches.

hep-ph↗
arXiv2004

New Application of the large-Nc expansion : comparison of the Gottfried and Adler sum rules

The Adler sum rule for deep inelastic neutrino scattering measures the isospin of the nucleus, and is hence exact. In contrast the Gottfried sum rule for charged lepton scattering does receive perturbative and non-perturbative corrections. We show that at two-loop level the Gottfried sum rule is suppressed by a factor 1/Nc^2 relative to higher moments, and we conjecture that this suppression holds to all-orders, and also for higher-twist effects. It is further noted that differences between radiative corrections for higher moments of neutrino and charged lepton deep inelastic scattering, are 1/Nc^2 suppressed at two-loops, and this is also conjectured to hold to all-orders. The 1/Nc^2 suppression of corrections to the Gottfried sum rule makes it plausible that the deviations from the parton model value are dominated by a light quark flavour asymmetry in the nucleon sea. This asymmetry indeed persists as Nc-->infinity as predicted in a chiral soliton model.

hep-ph↗
arXiv2004

Comparison of the Gottfried and Adler sum rules within the large-Nc expansion

The Adler sum rule for deep inelastic neutrino scattering measures the isospin of the nucleon and is hence exact. By contrast, the corresponding Gottfried sum rule for charged lepton scattering was based merely on a valence picture and is modified both by perturbative and non-perturbative effects. Noting that the known perturbative corrections to two-loop order are suppressed by a factor 1/N_c^2, relative to those for higher moments, we propose that this suppression persists at higher orders and also applies to higher-twist effects. Moreover, we propose that the differences between the corresponding radiative corrections to higher non-singlet moments in charged-lepton and neutrino deep inelastic scattering are suppressed by 1/N_c^2, in all orders of perturbation theory. For the first moment, in the Gottfried sum rule, the substantial discrepancy between the measured value and the valence-model expectation may be attributed to an intrinsic isospin asymmetry in the nucleon sea, as is indeed the case in a chiral-soliton model, where the discrepancy persists in the limit N_c-->infinity.

hep-ph↗
arXiv2003

The Gottfried sum rule: theory vs experiment

The current status of theoretical QCD calculations and experimental measurements of the Gottfried sum rule are discussed. The interesting from our point of view opened problems are summarised. Among them is the task of estimating the measure of light-quark flavour asymmetry in possible future experiments.

hep-ph↗
arXiv2003

The consequences of the relations between non-singlet contributions to $g_1^N$ and $F_1^N$ structure functions within infrared renormalon model

We report on the following consequences of the relations between non-singlet contributions to $g_1^N$ and $F_1^N$ structure functions found within infrared renormalon model: the discovery of new next-to-leading order inequalities between non-singlet polarized and unpolarized parton densities, and the existence of the effects of similarity between non-perturbative and perturbative contributions to the unpolarized and polarized Bjorken sum rules.

hep-ph↗
arXiv2003

Order $α_s^2$ perturbative QCD corrections to the Gottfried sum rule

The order $α_s^2$ perturbative QCD correction to the Gottfried sum rule is obtained. The result is based on numerical calculation of the order $α_s^2$ contribution to the coefficient function and on the new estimate of the three-loop anomalous dimension term. The correction found is negative and rather small. Therefore it does not affect the necessity to introduce flavour-asymmetry between $\bar{u}$ and $\bar{d}$ antiquarks for the description of NMC result for the Gottfried sum rule.

hep-ph↗
arXiv2003

The constraints on the non-singlet polarised parton densities from the infrared-renormalon model

Using the infrared-renormalon approach, we obtain the constraints on the next-to-leading order non-singlet polarised parton densities. The advocated feature follows from the consideration of the effect revealed in the process of the next-to-leading order fits to the data for the assymetry of polarised lepton-nucleon scattering which result in the approximate nullification of the $1/Q^2$-correction to A_1^N(x,Q^2).

hep-ph↗
arXiv2002

N^3LO fits to xF_3 data : $α_s$ vs 1/Q^2 contributions

The results of approximate N$^$3LO and detailed NNLO fits to $xF_3$ data of the CCFR'97 collaboration are presented. We demonstrate that $1/Q^2$ non-perturbative corrections to $xF_3$ modeled by three independent procedures are shadowed by perturbative QCD effects, starting at the NNLO. Special attention is paid to revealing the role of the recently calculated NNLO corrections to the anomalous dimensions and $N^3$LO corrections to the coefficient functions of odd moments of $xF_3$ with $n\leq 13$. The related values of $α_s(M_Z)$ are extracted.

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