Soft and hard Pomeron in the structure function of the proton at low x and low Q2
U. D'Alesio - A. Metz - H.J. Pirner
Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 19, D-69120 Heidelberg, Germany
Received: 6 December 1998 / Revised version: 19 April 1999 / Published online: 18 June 1999
We study inclusive electroproduction on the proton at low x and low Q2 using a soft and a hard Pomeron. The contribution of the soft Pomeron is based on the Stochastic Vacuum Model, in which a nonperturbative dipole-dipole cross section can be calculated by means of a gauge invariant gluon field strength correlator. To model the hard Pomeron exchange we phenomenologically extend the leading order evolution of a power-behaved structure function, , proposed by López and Ynduráin. This extension allows to consider both the case Q2 = 0 and the region of higher Q2 on the basis of the same parametrization. A good simultaneous fit to the data on F2 and on the cross section of real photoproduction is obtained for .With four parameters we achieve a for 222 data points. In addition, we use our model of the inclusive interaction to compute the longitudinal structure function FL.