arXiv subjects

A. V. Sidorov

Publications and source records attributed to A. V. Sidorov.

47 records · Page 3Linked to original sources

arXiv1997

Next-to-next-to-leading order QCD analysis of the revised CCFR data for xF_3 structure function and the higher twist contributions

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 extraction of the $x$-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 $α_s(M_Z)^{NNLO}=0.117 \pm 0.002(stat) \pm 0.005 (syst)\pm 0.003 (theory)$. 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.

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arXiv1996

Next-to-next-to-leading order QCD analysis of combined data for $xF_3$ structure function and higher--twist contribution

The simultaneous QCD analysis of the $xF_3$ structure functions measured in deep-inelastic scattering by several collaborations is done up to 3--loop order of QCD. The x dependence of the higher--twist contribution is evaluated and turns out to be in a qualitative agreement with the results of "old" CCFR data analysis and with renormalon approach predictions. The Gross--Llewellyn Smith sum rule and its higher--twist corrections are evaluated.

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arXiv1996

QCD analysis of the CCFR data for $xF_3$ and Higher--Twist Contribution

The QCD analysis of the $xF_3$ structure function measured in deep-inelastic scattering of neutrinos and antineutrinos on an iron target at the Fermilab Tevatron is done in 1--, 2-- and 3--loop order of QCD. The x dependence of the higher--twist contribution is evaluated. The experimental value of higher--twist corrections to the Gross--Llewellyn Smith sum rule is discussed.

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arXiv1996

Continuous mass-dependent analysis of the non--singlet DIS data

We consider the issue of an accurate description of the evolution of the non-singlet structure function moments $M_n(Q)$ near heavy quark threshold. To this aim we propose a simple modification of the standard massless \MSbar scheme approach to the next-to-leading QCD analysis of DIS data. We apply it to the processing of the modern CCFR data for $xF_3$ structure function and extract the value of $α_s(M_z) \approx 0.108 \pm 0.004$ We check also the consistency of light gluino hypothesis with CCFR data.

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arXiv1996

Experimental constraints on coefficients of $α_S$-expansion of Gottfried sum rule

The $x$- and $Q^2$-dependences of the Gottfried sum rule $S_G(x,Q^2)$ based on the experimental data on proton and deuteron structure functions are studied. The dependence of $S_G(x,Q^2)$ on $Q^2$ for low $x$ points to flavour asymmetry of sea quark distributions. For the first time, the coefficients $c_1, c_2$ of the expansion of $S_G(x,Q^2)$ in $α_S/π$ up to second order are evaluated through the phenomenological analysis of NMC and H1 data. It is found that $c_1$ is negative while $c_2$ is positive. The obtained result is in disagreement with QCD predictions for these coefficients. We suggest measuring the low $x$-dependence of the $F_2^D$ deuteron structure function at HERA in order to study the $Q^2$-dependence of the Gottfried sum rule.

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arXiv1996

On a Possibility to Determine the Sign of the Polarized Gluon Distribution

We investigate the possibility to draw conclusions on the sign of the spin-dependent gluon distribution, $ΔG(x, Q^2)$, from existing polarized DIS data. The spin-dependent parton distributions $Δu_v, Δd_v, Δ{\bar u}, Δ{\bar d}, Δ{s}$, and $ΔG$ are constructed in the framework of a phenomenological procedure taking into account some assumptions on signs of valence and sea parton distributions motivated by 't Hooft's mechanism of quark-quark interaction induced by instantons. The axial gluon anomaly and data on integral quark contributions to the proton spin, $Δ\tilde u, Δ\tilde d$, and $Δ\tilde s$, are also taken into account. Predictions for the $x$- and $Q^2$-dependencies of the polarized proton and neutron structure functions, $g_1^p$ and $g_1^n$, are compared to experimental data. It is shown that the neutron structure function, $g_1^n$, is especially sensitive to the sign of $ΔG(x, Q^2)$. The results of our analysis supports the conclusion that this sign should be positive.

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arXiv1996

On QCD $Q^2$-evolution of Deuteron Structure Function $F_2^D(x_D,Q^2)$ for $x_D>1$

The deep-inelastic deuteron structure function (SF) $F_2^D(x_D,Q^2)$ in the covariant approach in light-cone variables is considered. The $x_D$ and $Q^2$-dependences of SF are calculated. The QCD analysis of generated data both for non-cumulative $x_D<1$ and cumulative $x_D>1$ ranges was performed. It was shown that $Q^2$-evolution of SF is valid for ranges $0.275<x_D<0.85$ and $1.1<x_D<1.4$ for the same value of QCD scale parameter $Λ$. It was found the $x_D$-dependence of SF for the ranges is essentially different.

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arXiv1996

Constraints on "Second Order Fixed Point" QCD from the CCFR Data on Deep Inelastic Neutrino-Nucleon Scattering

The results of LO {\it Fixed point} QCD (FP-QCD) analysis of the CCFR data for the nucleon structure function $~xF_3(x,Q^2)~$ are presented. The predictions of FP-QCD, in which the Callan-Symanzik $~β~$ function admits a {\it second order} ultraviolet zero at $~α= α_0~$ are in good agreement with the data. Constraints for the possible values of the $~β~$ function parameter $~b~$ regulating how fast $~α_ s(Q^2)~$ tends to its asymptotic value $~α_{0}\ne 0~$ are found from the data. The corresponding values of $~α_{0}~$ are also determined. Having in mind our recent " First order fixed point" QCD fit to the same data we conclude that in spite of the high precision and the large $~(x,Q^2)~$ kinematic range of the CCFR data they cannot discriminate between QCD and FP-QCD predictions for $~xF_3(x,Q^2)~$.

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arXiv1996

Next-to-next-to-leading order QCD analysis of the CCFR data for xF_3 and F_2 structure functions of the deep-inelastic neutrino-nucleon scattering

The next-to-next-to-leading order (NNLO) non-singlet QCD analysis of the experimental data of the CCFR collaboration for the $xF_3$ and $F_2$ structure functions of the deep-inelastic scattering of neutrinos and antineutrinos on the nucleon by means of the Jacobi polinomial expansion method is made. The target mass corrections are also taken into account. We demonstrate that the NNLO corrections have the important: they are decreasing the difference between the values of $α_s(M_Z)$, extracted from the NLO fit of $xF_3$ data and from the NLO non-singlet fit of the combined $xF_3$ and $F_2$ CCFR data. The obtained NNLO results for $α_s(M_Z)$ are :$α_s(M_Z)=0.109 \pm 0.003(stat) \pm 0.005(syst) \pm 0.003 (theor)$ (from $xF_3$ data) and $α_s(M_Z)=0.111\pm 0.002 (stat) \pm 0.003 (syst) \pm 0.003 (theor)$ (from the combined $xF_3$ and $F_2$ data). We also estimate the values of the order $O(α_s^2)$-corrections to the Gottfried sum rule.

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arXiv1995

The QCD Analysis of the Structure Functions and Effective Nucleon Mass

On the basis of the target mass corrections to structure functions of deep-inelastic scattering of leptons, we evaluate effective nucleon mass that turns out to be twice $M_{nucl.}$ for deep-inelastic scattering on the nucleus target and equals $M_{nucl.}$ for the hydrogen target.

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arXiv1995

"Fixed point" QCD Analysis of the CCFR Data on Deep Inelastic Neutrino- Nucleon Scattering

The results of LO \it {Fixed Point} QCD (FP - QCD) analysis of the CCFR data for the nucleon structure function $~xF_3(x,Q^2)~$ are presented. The predic- tions of FP - QCD, in which $~α_s(Q^2)~$ tends to a nonzero coupling constant $~α_0~$ as $~Q^2\to \infty~$, are in good agreement with the data. The description of the data is even better than that in the case of LO QCD. The FP-QCD parameter $~α_0~$ is determined with a good accuracy: $~α_0 = 0.198\pm 0.009~$. Having in mind the recent QCD fits to the same data we conclude that unlike the high precision and large $~(x,Q^2)~$ kinematic range of the CCFR data they cannot discriminate between QCD and FP - QCD predictions for $~xF_3(x,Q^2)~$.

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