109 research outputs found
Two-loop calculations for the propagators of gluonic currents. Erratum
This is an erratum to the paper published in Nucl. Phys. B198(1982)508.Comment: 3 pages, Late
The improved 10th order QED expression for a_{\mu} : new results and related estimates
New estimates of the 10th order QED corrections to the muon anomalous
magnetic moment are presented. The estimates include the information on
definite improved 10th order QED contributions to , calculated by
Kinoshita and Nio. The final estimates are in good agreement with the ones,
given recently by Kinoshita.Comment: Presented at Working Group 4 of 7th Int. Workshop on Neutrino
Factories and Superbeams NuFact05, Frascati 21-26 June 2005; 3 double column
pages, LaTe
The NNLO QCD analysis of the CCFR data for xF_3: is there still the room for the twist-4 terms?
The results of the more detailed NNLO QCD analysis of the CCFR data for
SF are presented. The factorization scale uncertainties are analysed.
The NNLO results for and twist-4 contributions are obtained.
Despite the fact that the amplitude of the -shape of the twist-4 factor is
consequently decreasing at the NLO and NNLO, our new QCD analysis seems to
reveal the remaining twist-4 structure at the NNLO level. The definite NLO
uncertainties are fixed using the [0/2] Pad\'e resummation technique.Comment: LaTeX, 3 pages, 1 figure; to be published in the Proceedings of DIS99
Workshop, Zeuthen, April 19-23; some technical shortcomings are fixed in the
file, 2 referencies correcte
Order perturbative QCD corrections to the Gottfried sum rule
The order perturbative QCD correction to the Gottfried sum rule
is obtained. The result is based on numerical calculation of the order
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 and antiquarks for the
description of NMC result for the Gottfried sum rule.Comment: LaTeX, 7 pages, the discussions of the corrections to
the anomalous dimension are modified; 1 reference added; to be published in
Phys. Lett.
The NNLO non-singlet QCD analysis of parton distributions based on Bernstein polynomials
A non-singlet QCD analysis of the structure function up to NNLO is
performed based on the Bernstein polynomials approach. We use recently
calculated NNLO anomalous dimension coefficients for the moments of the
structure function in scattering. In the fitting procedure, Bernstein
polynomial method is used to construct experimental moments from the
data of the CCFR collaboration in the region of which is inaccessible
experimentally. We also consider Bernstein averages to obtain some unknown
parameters which exist in the valence quark densities in a wide range of
and . The results of valence quark distributions up to NNLO are in good
agreement with the available theoretical models. In the analysis we determined
the QCD-scale MeV (LO), 259 MeV (NLO)
and 230 MeV (NNLO), corresponding to LO,
NLO and NNLO. We compare our
results for the QCD scale and the with those obtained from
deep inelastic scattering processes.Comment: 20 pages, 7 figures, published in JHE
The Jacobi Polynomials QCD analysis for the polarized structure function
We present the results of our QCD analysis for polarized quark distribution
and structure function . We use very recently experimental data
to parameterize our model. New parameterizations are derived for the quark and
gluon distributions for the kinematic range , GeV^2. The analysis is based on the Jacobi polynomials
expansion of the polarized structure functions. Our calculations for polarized
parton distribution functions based on the Jacobi polynomials method are in
good agreement with the other theoretical models. The values of
and are determined.Comment: 23 pages, 8 figures and 4 table
The NLO DGLAP extraction of alpha_s and higher twist terms from CCFR xF_3 and F_2 structure functions data: results and scale dependence
We perform a detailed NLO analysis of the combined CCFR xF_3 and F_2
structure functions data and extract the value of alpha_s, parameters of
distributions and higher-twist (HT) terms using a direct solution of the DGLAP
equation. The value of alpha_s(M_Z)=0.1222\pm 0.0048 (exp) \pm 0.0026 (theor)
is obtained. Our results has a larger central value and errors than the
original one of the CCFR collaboration due to model independent
parameterization of the HT contributions. The dependence of HT contributions on
the QCD renormalization scale is studied.Comment: Contributed to Nucleon99 Proceedings (Frascati, June 7-9, 1999,
Italy), to appear in Nucl.Phys.
An Analytical Expression for the Non-Singlet Structure Functions at Small in the Double Logarithmic Approximation
A simple analytic expression for the non-singlet structure function
is given. The expression is derived from the result of Ref. [1] obtained by low
resummation of the quark ladder diagrams in the double logarithmic
approximation of perturbative QCD.Comment: 5 pages, A few comments and refs are adde
Bjorken unpolarized and polarized sum rules: comparative analysis of large-N_F expansions
Analytical all-orders results are presented for the one-renormalon-chain
contributions to the Bjorken unpolarized sum rule for the F_1 structure
function of nu N deep-inelastic scattering in the large-N_F limit. The
feasibility of estimating higher order perturbative QCD corrections, by the
process of naive nonabelianization (NNA), is studied, in anticipation of
measurement of this sum rule at a Neutrino Factory. A comparison is made with
similar estimates obtained for the Bjorken polarized sum rule. Application of
the NNA procedure to correlators of quark vector and scalar currents, in the
euclidean region, is compared with recent analytical results for the
O(alpha_s^4 N_F^2) terms.Comment: 9 page
N^3LO fits to xF_3 data : vs 1/Q^2 contributions
The results of approximate N^3LO and detailed NNLO fits to data of
the CCFR'97 collaboration are presented. We demonstrate that
non-perturbative corrections to 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 LO corrections to the
coefficient functions of odd moments of with . The related
values of are extracted.Comment: 5 pages, 1 figure, LaTeX; Contributed to the Proceedings of joint 6th
Symposium RADCOR 2002 and 6th Zeuthen Workshop Loops and Legs in Quantum
Field Theory, September 8-13, Kloster Banz, Germany; size of postscript
figure fixe
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