NONLINEARITIES AND POMERON NONFACTORIZABILITY IN CONVENTIONAL DIFFRACTION

Alternatives for describing the nonlinear behavior of the first diffra ction cone in differential pp and <(p)over bar p> elastic cross-sectio n are investigated. High-quality fits to the data are presented. We sh ow that the presence in the pomeron amplitude of two terms with differ ent t dependences is strongly suggested by the data, hinting at a non- factorizable pomeron even in the field of purely hadronic reactions. T he available data, however, do no allow to choose among a nonlinearity in the residues or in the pomeron trajectory or in both. In all cases , we find an effective slope of the trajectory larger than the one cur rently used. A nonlinear trajectory with the fitted parameters is used for predicting the mass and the width of the 2(++) glueball. An excel lent agreement is found with the X(1900) candidate from the WA91 exper iment.