The effect of the infrared phase of the discrete BFKL pomeron on transverse momentum diffusion

A bstract Imposing infrared boundary conditions on the BFKL equation with running coupling transforms the complex momentum ω -plane cut present in the gluon Green function into an infinite series of positive Regge poles. In addition, a cut on the negative ω line remains. We consider a Hermitian kernel at leading order with running coupling and construct the gluon Green function performing the ω integration away from the real axis. We find a strong dependence of the asymptotic intercepts and collinear behaviour on the non-perturbative choice of the boundary conditions, in the form of an infrared phase. This is particularly manifest in the asymmetric infrared/ultraviolet structure of the associated diffusion in transverse momentum. We find that random walks into the infrared region are largely reduced in this approach.