A STRUCTURE-FUNCTION TEST OF THE QCD LIPATOV BEHAVIOR AT HERA

The structure functions for deep-inelastic electron-proton scattering at small x are calculated using the QCD k(T)-factorization theorem tog ether with the gluon distribution obtained from solving the Lipatov (o r BFKL) equation. We study the theoretical uncertainties in the predic tions and show, in the HERA regime, that the effective slope lambda, d efined by F-2(x,Q(2))-F-2(bg)(x,Q(2))=Cx(-lambda), is a remarkably sta ble prediction of perturbative QCD, where F-2(bg) is suitably defined background. We propose a procedure for identifying the Lipatov effect from small x measurements of F-2. We apply it to the recent HERA data, and hence determine lambda.