Renormalization of twist-4 operators in QCD Bjorken and Ellis-Jaffe sum rules

The QCD effects of twist-4 operators on the first moment of nucleon spin-dependent structure function g_1(x, Q^2 ) are studied in the framework of operator product expansion and renormalization group method. We investigate the operator mixing through renormalization of the twist-4 operators including those proportional to the equation of motion by evaluating off-shell Green's functions. Through this procedure we extract the one-loop anomalous dimension of the spin 1 and twist-4 operator which determines the logarithmic correction to the 1/Q^2 behavior of the contribution from the twist-4 operators to the first moment of g_1(x,Q^2)