Shadowing correction to the gluon distribution behavior at small x

Abstract

We determined the saturation exponent of the gluon distribution using the solution of the QCD nonlinear Dokshitzer-Gribov-Lipatov-Altarelli-parisi (NLDGLAP) evolution equation at small $x$. The very small $x$ behavior of the gluon distribution is obtained by solving the Gribov, Levin, Ryskin, Mueller and Qiu (GLR-MQ) evolution equation with the nonlinear shadowing term incorporated. The form of initial condition for the equation is determined. We find, with decreasing $x$, the emergence of a singular behavior and the eventual taming (at $R=5\hspace{0.1cm}GeV^{-1}$) and the essential taming (at $R=2\hspace{0.1cm}GeV^{-1}$) of this singular behavior by shadowing term. The nonlinear gluon density functions are calculated and compared with the results for the integrated gluon density from the Balitsky- Kovchegov(BK) equation for the different values of $Q^{2}$. It is shown, that the results for the gluon density function are comparable with the results obtained from BK equation solution. Also we show that for each $x$, the $Q^{2}$ dependence of the data is well described by gluon shadowing corrections to GLR-MQ equation. The resulting analytic expression allow us to predict the logarithmic derivative $\frac{{\partial}F^{s}_{2}(x,Q^{2})}{{\partial}lnQ^{2}}$ and to compare the results with H1 data and a QCD analysis fit.