Screening corrections in DIS at low Q^2 and x

TL;DR

This paper investigates the derivative of the structure function in deep inelastic scattering at low Q^2 and x, using a coupled analysis of J/Ψ production and DIS data to test and refine QCD models with corrections.

Contribution

It introduces a detailed coupled analysis of J/Ψ production and DIS to improve the understanding of gluon distributions and incorporates specific corrections in pQCD calculations at low Q^2 and x.

Findings

Reproduces recent HERA data well with corrected GRV98NLO model.

Determines the parameter R^2=8.5 GeV^{-2} from J/Ψ photoproduction data.

Achieves excellent fit to J/Ψ and DIS production data using the model.

Abstract

In this investigation we present a detailed study of $\partial F_2/\partial \ln Q^2$ which is supported by a coupled analysis of $J/\Psi$ photo and DIS production. Both channels are directly proportional to $xG(x,Q^2)$, and as such serve as excellent discriminators between different approaches and models. We then show that taking GRV98NLO as input and correcting it for SC, we can reproduce the recent HERA data well. The calculation depends on one parameter $R^2=8.5GeV^{-2}$ which is directly determined from the $J/\Psi$ photoproduction forward differential slope. With this input we obtain an excellent fit to the $J/\Psi$ photo and DIS production data. Our calculations made in the LLA of pQCD take into account the corrections implied by the real part of the production amplitude, off diagonal (skewed) gluon distributions and the Fermi motion of the charm quarks within the bound Charmonium system.