Moments of singlet parton densities on the lattice in the Schroedinger Functional scheme
arXiv:hep-lat/0203002 · doi:10.1016/S0550-3213(02)00407-8
Abstract
A non perturbative computation of the evolution of singlet parton densities without gauge--fixing requires a gauge invariant gluon source operator. Within the Schrödinger Functional scheme (SF), such a source can be defined in terms of path ordered products of gauge links, connected to the time boundaries. In this paper we adopt this definition and perform a one loop lattice computation of the renormalization constants of the twist--2 operators that correspond to the second moment of singlet parton densities. This calculation fixes the connection between the lattice SF scheme where a non perturbative evaluation of the absolute normalization of singlet parton densities can be made at low energy and the $\bar{MS}$ scheme where one can extract the experimental values.
38 pages, 16 figures