ANOMALOUS DIMENSION OF THE TWIST 4 GLUON OPERATOR AND POMERON CUTS IN DEEP INELASTIC-SCATTERING

The anomalous dimension of the twist four gluonic operator (gamma4) in deep inelastic scattering is calculated in the double log approximation (DLA) of perturbative QCD. It turns out that at N --> 1 gamma4(N - 1) is close to 2gamma2((N - 1)/2) where gamma2 is the anomalous dimension of the leading twist operator. It means that at N --> 1 the contribution of the twist four operator to the deep inelastic structure function becomes very important and gives rise to the screening correction to the deep inelastic structure function as was taken into account in the nonlinear GLR evolution equation.