Eur. Phys. J. C 16, 337-347
DOI 10.1007/s100520000369
Structure function of the nucleus in the perturbative
QCD
with
(BFKL pomeron fan diagrams)
M. Braun
Department of High Energy Physics,
University of St. Petersburg,
198904 St. Petersburg, Russia
Received: 26 January 2000 / Published online: 8 June 2000 - © Springer-Verlag 2000
Abstract
The equation for the sum of BFKL pomeron fan diagrams
is rederived by a direct summation and
solved
numerically for rapidities 
.
At high rapidities, y>20,
the resulting cross-sections for the scattering of a longitudinally
polarized 
pair on
the nucleus cease to depend on its transverse dimension and tend
to a
constant limit of
0.1768 RA2, which corresponds to scattering
of
a color dipole on a black disk.
Thus the
unitarity is restored and the
singularity in the j plane is reduced to a simple pole at j=1.
The nuclear
structure function at small x behaves as
.
The gluon density found has a
soliton-like form in the 
space: its form is close to
Gaussian,
independent
of rapidity, the center
moving towards higher
with a nearly constant velocity
as
the rapidity increases.
Copyright Società Italiana di Fisica, Springer-Verlag 2000
