Ballistic protons in incoherent exclusive vector meson production as a measure of rare parton fluctuations at an Electron-Ion Collider

TL;DR

This paper proposes using proton multiplicities in Roman pot detectors at an Electron-Ion Collider to classify event centrality in incoherent diffractive scattering, revealing fluctuations in multi-parton interactions and saturation scales.

Contribution

It introduces a novel method to determine centrality classes in incoherent diffraction by analyzing proton multiplicities, linking fluctuations in parton dynamics to measurable observables.

Findings

Proton multiplicities can classify event centrality in incoherent diffraction.

Central events exhibit higher saturation scales than minimum bias events.

An observable sensitive to parton fluctuations and centrality is identified.

Abstract

We argue that the proton multiplicities measured in Roman pot detectors at an electron ion collider can be used to determine centrality classes in incoherent diffractive scattering. Incoherent diffraction probes the fluctuations in the interaction strengths of multi-parton Fock states in the nuclear wavefunctions. In particular, the saturation scale that characterizes this multi-parton dynamics is significantly larger in central events relative to minimum bias events. As an application, we study the centrality dependence of incoherent diffractive vector meson production. We identify an observable which is simultaneously very sensitive to centrality triggered parton fluctuations and insensitive to details of the model.