SMALL-X - 2 POMERONS

Regge theory provides a very simple and economical description of data for (i) the proton structure function with x < 0.7 and all available Q(2) values, (ii) the charm structure function, and (iii) gamma p --> J/psi p. The data are all in agreement with the assumption that there is a second pomeron, with intercept about 1.4. They suggest also that the contribution from the soft pomeron is higher twist. This means tha t there is an urgent need to make perturbative evolution compatible wi th Regge theory at small and not-so-small x, and to reassess the magni tude of higher-twist contributions at quite small x. (C) 1998 Elsevier Science B.V. All rights reserved.