This page contains material intended to supplement hep-ph/0204287, written
in collaboration with Ciafaloni, Colferai and Stasto. It provides
mpeg movies showing the evolution of BFKL "cigars" as one varies
the total rapidity *Y* of a high energy collision. These
cigars indicate the regions in rapidity and (log) transverse
momentum space which contribute significantly to the BFKL
evolution.

The movies illustrate the transition to the non-perturbative
region, which in certain situations occurs through an abrupt
tunneling transition.

They are given for three values of
*t*=ln*Q*^{2}, where *Q*^{2} is the
scale of the colliding objects. The evolution used is leading-log
BFKL with a coupling which runs as a function of the emitted
transverse momenta. The non-perturbative region is modeled by a
cutoff at *t*=4 (except in the last set of movies). The values
used are not intended to be phenomenologically relevant, but rather
have been chosen to illustrate the dynamics at play.

The links labeled "ducks" show vertical cross sections through
the centers of the movie frames, as a function of *Y*.

The picture on the left (a BFKL "alien") is a frame from one of
the movies (*t*=20) illustrating a transition (tunneling)
stage.

Gavin Salam
Last modified: Mon Sep 6 14:48:28 CEST 2004