The NNLO QCD analysis of gluon distribution function at small-x

Abstract

A next-to-next-to-leading order (NNLO) QCD calculation of gluon distribution function at small-x is presented. The gluon distribution function is explored analytically in the DGLAP approach by a Taylor expansion at small x as two first order partial differential equations in two variables : Bjorken x and t (t = ln(Q2/{\Lambda}2) ). We have solved the system of equations at LO, NLO and NNLO respectively by the La- granges method. The resulting analytical expressions are compared with the available global PDF sets as well as with the results of the BDM model. We have further performed a ḩi}2 test to check the com- patibility of our predictions and observed that our results can be consistently described in the context of perturbative QCD. A comparative analysis of the obtained results at LO, NLO and NNLO reveals that the NNLO approximation has a significant contribution to the gluon distribution function particularly in the small-x region.

Comments: 32 pages, 23 figures