A DIRECT TEST OF PERTURBATIVE QCD AT SMALL-X

We show that recent data from HERA on the proton structure function F-2 at small x and large Q(2) provide a direct confirmation of the double asymptotic scaling prediction of perturbative QCD. A linear rise of In F-2 With the scaling variable sigma is observed throughout the kinematic region probed at HERA, and the measured slope is in excellent agreement with the QCD prediction. This provides a direct determination of the leading coefficient of the beta function. At large values of the scaling variable rho the data display a small but statistically significant scaling violation.