Aleksander V. Sidorov

Determination of polarized parton densities from a QCD analysis of inclusive and semi-inclusive deep inelastic scattering data

A new combined next to leading order QCD analysis of the polarized inclusive and semi-inclusive deep inelastic lepton-hadron scattering (DIS) data is presented. In contrast to previous combined analyses, the 1/Q 2 terms (kinematic - target mass corrections, and dynamic - higher twist corrections) in the expression for the nucleon spin structure function g1 are taken into account. The new COMPASS data are included in the analysis. The impact of the semi-inclusive data on the polarized parton densities (PDFs) and on the higher twist corrections is discussed. The new results for the PDFs are compared to our (Leader, Sidorov, Stamenov) LSS’06 PDFs, obtained from the fit to the inclusive DIS data alone, and to those obtained from the de Florian, Sassot, Stratmann, and Vogelsang global analysis.

Higher twists and αs(MZ) extractions from the NNLO QCD analysis of the CCFR data for the xF3 structure function

Abstract A detailed next-to-next-to-leading order (NNLO) QCD analysis is performed for the experimental data of the CCFR collaboration for the xF 3 structure function. Theoretical ambiguities of the results of our NNLO fits are estimated by application of the Pade resummation technique and variation of the factorization and renormalization scales. The NNLO and N 3 LO α s ( Q 2 ) MS -matching conditions are used. In the process of the fits we are taking account of twist-4 1/ Q 2 -terms. We found that the amplitude of the x-shape of the twist-4 factor is decreasing in NLO and NNLO, though some remaining twist-4 structure seems to retain in NNLO in the case when only statistical uncertainties are taken into account. The question of the stability of these results to the application of the [0/2] Pade resummation technique is considered. Our NNLO results for α s ( M Z ) values, extracted from the CCFR xF 3 data, are α s ( M Z )=0.118±0.002(stat)±0.005(syst)±0.003(theory) provided the twist-4 contributions are fixed through the infrared renormalon model and α s ( M Z )=0.121 +0.007 −0.010 (stat)±0.005(syst)±0.003(theory) provided the twist-4 terms are considered as free parameters.

NEXT-TO-NEXT-TO-LEADING ORDER QCD ANALYSIS OF THE REVISED CCFR DATA FOR XF3 STRUCTURE FUNCTION AND THE HIGHER TWIST CONTRIBUTIONS

Abstract We present the results of the next-to-next-to-leading order QCD analysis of the recently revised experimental data of the CCFR collaboration for the xF 3 structure function using the Jacobi polynomial expansion method. The effects of the higher twist contributions are included into the fits following the infrared renormalon motivated model. The special attention is paid to the checks of the predictive abilities of the infrared renormalon model and to the independent extractions of the x -dependent shape of the twist-4 contributions to the xF 3 structure function in the process of the leading order, next-to-leading order and next-to-next-to-leading order fits of the revised CCFR data. We stress that at the next-to-next-to-leading order the results for α s ( M Z ) turn out to be almost nonsensitive to the higher-twist terms. We obtain the following result α s NNLO ( M Z )=0.117±0.002(stat)±0.005(syst)±0.003(theory). The comparison of the outcomes of our next-to-leading order and next-to-next-to-leading order analysis indicate that the theoretical QCD uncertainties were underestimated in the process of the next-to-leading order determination of α s ( M Z ), made recently by the CCFR collaboration itself.We present the results of the next-to-next-to-leading order QCD analysis of the recently revised experimental data of the CCFR collaboration for the

Longitudinal polarized parton densities updated

xF_3

Impact of CLAS and COMPASS data on polarized parton densities and higher twist

structure function using the Jacobi polynomial expansion method. The effects of the higher twist contributions are included into the fits following the infrared renormalon motivated model. The special attention is paid to the checks of the predictive abilities of the infrared renormalon model and to the independent extraction of the

Test of QCD and a measurement of Λ from scaling violations in the proton structure function F2(x, Q2) at high Q2

x

A new evaluation of polarized parton densities in the nucleon

-shape of the twist-4 contributions to the

Test of QCD and a measurement of Λ from scaling violations in the nucleon structure function F2(x,Q2)

xF_3

NLO QCD ANALYSIS OF POLARIZED DEEP INELASTIC SCATTERING

structure function in the process of the leading order, next-to-leading order and next-to-next-to-leading order fits of the revised CCFR data. We stress that at the next-to-next-to-leading order the results for

Next to next-to-leading order QCD analysis of the CCFR data for xF3 and F2 structure functions of the deep inelastic neutrino - nucleon scattering

\alpha_s(M_Z)