Small-xbehavior of the singlet polarized structure functiong2in the double logarithmic approximation

Abstract

The small-$x$ behavior of the singlet contributions to the polarized structure function ${g}_{2}{(x,Q}^{2})$ is calculated in the double-logarithmic approximation of perturbative QCD. The dominant contribution is due to the gluons which, in contrast with the unpolarized case, mix with the fermions also in the small-$x$ domain. We find a powerlike growth in $1/x$ in the odd-signature parts of the amplitude with the same power as in the singlet function ${g}_{1}{(x,Q}^{2})$ at $x\ensuremath{\ll}1.$