Large $\mathbf{b}$ behaviour in the CGC/saturation approach: BFKL equation with pion loops

Abstract

In this paper we proposed a solution to the longstanding problem of the CGC/saturation approach: the power-like fall of the scattering amplitudes at large $b$. This decrease leads to the violation of the Froissart theorem and makes the approach theoretically inconsistent. We showed in the paper that sum of the pion loops results in the exponential fall of the scattering amplitude at large impact parameters and in the restoration of the Froissart theorem.