Impact of the three-loop corrections on the QCD analysis of the deep-inelastic-scattering data

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 $α_{s}(M_Z)=0.1143\pm0.0013 (exp)$ 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.

Figures (4)

• Figure 1: The ratios of the leading twist structure functions $F_{2,\rm L}$ calculated in the NNLO and the NLO approximations.
• Figure 2: Ratio of the logarithmic derivatives of the gluon distribution $G'=d\ln G/d \ln Q$ calculated in the NNLO and the NLO approximations (left); the same for the singlet distribution (right). The dotted curves correspond to the choice A and the dashed curves -- to the choice B for the splitting functions approximations of Ref. vanNeerven:2000wp.
• Figure 3: The selected PDFs obtained from the NNLO fits with the different choice of the NNLO splitting functions. (Full curves: the $1\sigma$ experimental bands for the fit with the splitting functions chosen as average of the variants A and B of Ref. vanNeerven:2000wp; dashed curves: the central values for the fit with variant B of Ref. vanNeerven:2000wp).
• Figure 4: The $1\sigma$ bands for the gluon distributions obtained in the NNLO (full lines) and the NLO (dashed lines) analysis at different values of $Q$.