Rapidity gap distribution in diffractive deep-inelastic scattering and parton genealogy

A H Mueller,S Munier

doi:10.1103/physrevd.98.034021

Abstract

We propose a partonic picture for high-mass diffractive dissociation events in onium-nucleus scattering, which leads to simple and robust predictions for the distribution of the sizes of gaps in diffractive dissociation of virtual photons off nuclei at very high energies. We show that the obtained probability distribution can formally be identified to the distribution of the decay time of the most recent common ancestor of a set of objects generated near the edge of a branching random walk, and explain the physical origin of this appealing correspondence. We then use the fact that the diffractive cross section conditioned to a minimum rapidity gap size obeys a set of Balitsky-Kovchegov equations in order to test numerically our analytical predictions. Furthermore, we show how simulations in the framework of a Monte Carlo implementation of the QCD evolution support our picture.

Highlights

In scattering processes at energies much larger than the typical mass of the hadrons, a nucleus appears as a weakly bound system of nucleons, themselves made of dense sets of partons
We show that the obtained probability distribution can formally be identified to the distribution of the decay time of the most recent common ancestor of a set of objects generated near the edge of a branching random walk, and explain the physical origin of this appealing correspondence
II, after a short review of high-energy evolution and scattering, we introduce our picture of diffraction, and explain how it connects to the general problem of ancestry in branching random walks

Summary

Introduction

In scattering processes at energies much larger than the typical mass of the hadrons (for a review on high-energy scattering, see Ref. [1]), a nucleus appears as a weakly bound system of nucleons, themselves made of dense sets of partons. It turns out that the scattering of a hadronic projectile or of a virtual photon off a target (which may be a nucleus or a proton) leaves the latter intact with a significant probability, which even tends to. This phenomenon is predicted by basic quantum mechanics. It was clearly observed in proton and antiproton collisions (for reviews, see [2,3]), in proton-nucleus collisions (the nucleus being left intact, which is the case we are interested in here) at CERN [4], and later in virtual photon-proton scattering at DESY HERA [5,6] It was clearly observed in proton and antiproton collisions (for reviews, see [2,3]), in proton-nucleus collisions (the nucleus being left intact, which is the case we are interested in here) at CERN [4], and later in virtual photon-proton scattering at DESY HERA [5,6] (for a review, see Ref. [7])

Methods

Results

Conclusion