Exclusive final states in diffractive excitation

TL;DR

This paper presents a new formalism for generating exclusive final states in diffractive excitation using an optical analogy and the Good--Walker formalism, implemented in the DIPSY event generator, with promising initial results.

Contribution

It introduces a novel formalism for exclusive diffractive final states based on absorption and quantum interference, integrated into an event generator without additional tunable parameters.

Findings

Formalism successfully models diffractive excitation in DIS and proton-proton collisions.

Implementation in DIPSY matches experimental data reasonably well.

No additional tunable parameters needed beyond previous non-diffractive studies.

Abstract

In this paper we describe a formalism for generating exclusive final states in diffractive excitation, based on the optical analogy where diffraction is fully determined by the absorption into inelastic channels. The formalism is based on the Good--Walker formalism for diffractive excitation, and it is assumed that the virtual parton cascades represent the diffractive eigenstates defined by a definite absorption amplitude. We emphasize that, although diffractive excitation is basically a quantum-mechanical phenomenon with strong interference effects, it is possible to calculate the different interfering components to the amplitude in an event generator, add them and thus calculate the reaction cross section for exclusive diffractive final states. The formalism is implemented in the DIPSY event generator, introducing no tunable parameters beyond what has been determined previously in studies of non-diffractive events. Some early results from DIS and proton-proton collisions are presented, and compared to experimental data.