Rare fluctuations and the high-energy limit of the S-matrix in QCD

Abstract

We argue that one cannot correctly calculate the elastic scattering S-matrix for high-energy dipole-dipole scattering, in the region where S is small, without taking fluctuations into account. The relevant fluctuations are rare and unimportant for general properties of inelastic collisions. We find that the Kovchegov equation, while giving the form of the S-matrix correctly, gives the exponential factor twice as large as the result which emerges when fluctuations are taken into account.