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匹配条件: “Evgeny ALEKHIN” ,找到相关结果约1002条。
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Assessment of Current State of Urban Resettlement in a Russian Region. Case Study: Orel Region
Evgeny ALEKHIN,Vladimir TIKHII
Journal of Settlements and Spatial Planning , 2012,
Abstract: This article gives the evaluation of the state of urban resettlement in Orel region, one of the Central Russia provinces. It provides the research of the change in urban population of the region, urbanization dynamics. The article reveals the main reasons for the decrease in urbanization intensity, gives the analysis of the rate of urbanization in terms of administrative districts of the region, provides the classification of urban settlements of the region according to population and researches the changes in urban population resettlement during intercensal periods.
Extraction of parton distributions and $α_s$ from DIS data within the Bayesian treatment of systematic errors
Sergey Alekhin
Physics , 1996, DOI: 10.1007/s100520050763
Abstract: We have performed the NLO QCD global fit of BCDMS, NMC, H1 and ZEUS data with full account of point-to-point correlations using the Bayesian approach to the treatment of systematic errors. Parton distributions in the proton associated with experimental uncertainties, including both statistical and systematic ones were obtained. The gluon distribution in the wide region of $x$ was determined and it turned out to be softer than in the global analysis using prompt photon data. We also obtained the robust estimate of $\alpha_s(M_Z) = 0.1146\pm0.0036 (75% C.L.)$ based on Chebyshev's inequality, which is compatible with the earlier determination of $\alpha_s$ from DIS data, but with less dependence on high twist effects.
Value of $α_s$ and high twists from combined analysis $e-μ$ DIS data
Alekhin Sergey
Physics , 1999,
Abstract: We perform a NLO QCD analysis of the combined SLAC-BCDMS-NMC-E665-H1-ZEUS data on inclusive deep inelastic cross section. Particular attention was paid to the extraction of strong coupling constant $\alpha_s$ and high twist (HT) contribution to the structure functions $F_2$ and $F_L$. It was shown that at small and moderate x there is a visible dependence of the extracted values of HT contribution to $F_2$ on the QCD renormalization scale, which indicates that in this region extracted HT can absorb NNLO QCD corrections. At larger x the dependence of HT on the renormalization scale is negligible and the influence of NNLO correction on their values should be less significant. The value of $\alpha_s(M_Z)=0.1159\pm0.0031$ (total) is obtained, where the error includes statistical, systematical and theoretical uncertainties.
The QCD renormalization scale stability of high twists and $α_s$ in deep inelastic scattering
Alekhin Sergey
Physics , 1999,
Abstract: A sensitivity of twist-4 and $\alpha_s$ values extracted in the NLO QCD analysis of nonsinglet SLAC-BCDMS-NMC deep inelastic scattering data to the choice of QCD renormalization scale (RS) is analysed. It is obtained that the high twist (HT) contribution to structure function $F_2$, is retuned with the change of RS. This retuning depends on the choice of starting QCD evolution point $Q_0$ and x. At $Q_0 > 10 GeV^2$ the HT contribution to $F_2$ is retuned at small $x$ and almost not retuned at large $x$; at small $Q_0$ it exhibits approximate RS stability for all x in question. The HT contribution to $F_ L$ is RS stable for all $Q_0$ and x. The RS sensitivity of $\alpha_s$ also depends on the choice of $Q_0$: at large $Q_0$ this sensitivity is weaker, than at small one. For $Q_0^2=9 GeV^2$ the value $\alpha_s(M_Z)=0.1183\pm0.0021(stat+syst)\pm0.0013(RS)$ is obtained. Connection with the higher order QCD corrections is discussed.
Statistical properties of the estimator using covariance matrix
Alekhin Sergey
Physics , 2000,
Abstract: The statistical properties of estimator using covariance matrix for the account of point-to-point correlations due to systematic errors are analyzed. It is shown that the covariance matrix estimator (CME) is consistent for the realistic cases (when systematic errors on the fitted parameters are not extremely large comparing with the statistical ones) and its dispersion is always smaller, than the dispersion of the simplified $\chi^2$ estimator applied to the correlated data. The CME bias is negligible for the realistic cases if the covariance matrix is calculated during the fit iteratively using the parameter estimator itself. Analytical formula for the covariance matrix inversion allows to perform fast and precise calculations even for very large data sets. All this allows for efficient use of the CME in the global fits.
Global fit to the charged leptons DIS data: \boldmath{$α_{\rm s}$,} parton distributions, and high twists
Alekhin Sergey
Physics , 2000,
Abstract: We perform the NLO QCD analysis of the world data on inclusive deep inelastic scattering cross sections of charged leptons off the proton and the deuterium targets. The parton distributions, the value of strong coupling constant $\alpha_{\rm s}$, and the twist 4 contributions to the structure functions $F_2$ and $F_{\rm L}$ are extracted with the complete account for the correlations of data points due to the systematic errors. Sensitivity of the $\alpha_{\rm s}$ value and the high twist contribution to the procedures of accounting for the systematic errors is studied. The impact of theoretical uncertainties on the value of $\alpha_{\rm s}$ and on the parton distributions is analysed. The obtained value of strong coupling constant with the account of these uncertainties is $\alpha_{\rm s}(M_{\rm Z})=0.1165\pm0.0017({\rm stat+syst}) \pm^{0.0026}_{0.0034}({\rm theor})$. The uncertainties of parton-parton luminosities for the FNAL and LHC colliders are estimated.
Impact of the three-loop corrections on the QCD analysis of the deep-inelastic-scattering data
Alekhin Sergey
Physics , 2001, DOI: 10.1016/S0370-2693(01)01090-5
Abstract: We perform the analysis of the existing inclusive deep inelastic scattering (DIS) data within NNLO QCD approximation. The parton distributions functions (PDFs) and the value of strong coupling constant $\alpha_{s}(M_Z)=0.1143\pm0.0013 (exp)$ are obtained. The sensitivity of the PDFs to the uncertainty in the value of the NNLO corrections to the splitting functions is analyzed. It is shown that the PDFs errors due to this uncertainty is generally less than the experimental uncertainty in PDFs through the region of $x$ spanned by the existing DIS data.
Combined analysis of SLAC-BCDMS-NMC data at high x: α_s and high twists
Alekhin Sergey
Physics , 1999,
Abstract: We perform a NLO QCD analysis of the nonsinglet part of the combined SLAC-BCDMS-NMC data on inclusive deep inelastic cross section with the extraction of $\alpha_s$. We show that the value of $\alpha_s$ obtained in the analysis is sensitive to the statistical inference procedures dealing with systematic errors on the data. The fit with the complete account of point-to-point correlations of the data gives the value of $\alpha_s(M_Z)=0.1183\pm0.0021(exp.)\pm0.0013(ren.scale)$ that is compatible with the LEP measurements and the world average. Model independent x-shape of high twist contributions to the structure functions $F_L$ and $F_2$ is extracted. Twist-4 contribution to $F_L$ is found to be in qualitative agreement with the predictions of infrared renormalon model. Twist-6 contribution to $F_L$ exhibit weak trend to negative values, and twist-6 contribution to $F_2$ - to positive values, although both are compatible with zero within errors.
On the value of $α_s$ from the analysis of the SLAC/BCDMS deep inelastic scattering data
Alekhin Sergey
Physics , 1998, DOI: 10.1103/PhysRevD.59.114016
Abstract: We performed NLO QCD analysis of the nonsinglet part of the combined SLAC/BCDMS data on $F_2$ with the extraction of $\alpha_s$ and high twist contribution. It was shown that the value of $\alpha_s$ obtained in the analysis is sensitive to the statistical inference procedures dealing with systematic errors on the data. The fit with the complete account of point-to-point correlations of the data gave the value of $\alpha_s(M_Z)=0.1180\pm0.0017 (68% C.L.)$, to be compared with the previously reported value of $\alpha_s(M_Z)=0.113\pm0.003 (99% C.L.)$. This new value of $\alpha_s$ is compatible with the LEP measurements and the world average. The high twist contribution being strongly anti-correlated with the value of $\alpha_s$ became lower than it was previously reported.
High twist contribution to the longitudinal structure function $F_L$ at high $x$
Alekhin Sergey
Physics , 1999, DOI: 10.1007/s100520000179
Abstract: We performed NLO QCD fit of combined SLAC/BCDMS/NMC DIS data at high $x$. Model independent x-shape of high twist contribution to structure function $F_L$ is extracted. Twist-4 contribution is found to be in fair agreement with the predictions of infrared renormalon model. Twist-6 contribution exhibits weak tendency to negative values, although in the whole is compatible with zero within errors.
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