91 research outputs found
Monte Carlo calculations for the hard Pomeron
Starting from the same input as the standard BFKL Pomeron, we directly
calculate the ``hard'' Pomeron as a gluonic ladder by using Monte Carlo
methods. We reproduce the characteristic features of the the BFKL Pomeron and
are now also able to evaluate new observables. The applicability of the BFKL
approach under realistic kinematical conditions can be tested and the influence
of the running coupling constant examined.Comment: 9 pages and 4 figures included. To appear in Phys.Lett.
On the re-summation of enhanced Pomeron diagrams
Dominant contributions of enhanced Pomeron diagrams to elastic hadron-hadron
scattering amplitude are re-summed to all orders. The formalism is applied to
calculate total hadronic cross sections and elastic scattering slopes. An
agreement with earlier results is obtained
The BFKL Pomeron with running coupling constant: how much of its hard nature survives?
We discuss the BFKL equation with a running gauge coupling and identify in
its solutions the contributions originating from different transverse momentum
scales. We show that for a running coupling constant the distribution of the
gluons making up the BFKL Pomeron shifts to smaller transverse momenta so that
the dominant part of Pomeron can have a nonperturbative origin. It is
demonstrated how this soft physics enters into the BFKL solution through the
boundary condition. We consider two kinematical regimes leading to different
behaviour of the rapidity and transverse momentum dependence of the gluon
distribution. In the diffusion approximation to the BFKL kernel with running
, we find a sequence of poles which replaces the cut for fixed
. The second regime corresponds to the singular part of the kernel,
which gives the dominant contribution in the limit of very large transverse
momenta. Finally, a simple more general picture is obtained for the QCD Pomeron
in hard processes: it is of soft, nonperturbative nature, but has hard ends of
DGLAP-type.Comment: 23 pages REVTEX and 4 figures include
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