The Effect of a Rapidity Gap Veto on the Discrete BFKL Pomeron
  We investigate the sensitivity of the discrete BFKL spectrum, which appears in the gluon Green function when the running coupling is considered, to a lower cut-off in the relative rapidities of the emitted particles. We find that the eigenvalues associated to each of the discrete eigenfunctions decrease with the size of the rapidity veto. The effect is stronger on the lowest eigenfunctions. The net result is a reduction of the growth with energy for the Green function together with a suppression in the regions with small transverse momentum. 
Douglas A. Ross and Agustin Sabio Vera
hep-ph