Soft and Hard Pomeron in the Structure Function of the Proton at Low x and Low Q² · arXivDesk
hep-ph/9811349Nov 16, 199818 pages, Latex, 6 PS-figures, Regge-exchange neglected, more details concerning the soft Pomeron included, section on the longitudinal structure function added, all conclusions unchanged, final version to appear in Eur. Phys. J. C
Soft and Hard Pomeron in the Structure Function of the Proton at Low x and Low Q^2
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, F2∝x−λ
Nearby in the stack
, 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
σγp
of real photoproduction is obtained for
λ=0.37
. With four parameters we achieve a
χ2/d.o.f.=0.98
for 222 data points. In addition, we use our model of the inclusive
γ∗p
interaction to compute the longitudinal structure function