Decisive test of color coherence in proton-nucleus collisions at the LHC

TL;DR

This paper proposes an experimental test to distinguish between the Color Glass Condensate model and the Wounded Nucleon Model by analyzing how charged particle multiplicity depends on the number of participants in proton-nucleus collisions at LHC energies.

Contribution

It introduces a novel experimental approach to test color coherence in p+A collisions, differentiating between CGC and WNM predictions based on multiplicity dependence.

Findings

Multiplicity depends logarithmically on N_{part} in CGC.

Multiplicity depends linearly on N_{part} in WNM.

Proposes a new experimental test to validate color coherence models.

Abstract

Proton-nucleus collisions (p+A) at LHC energies provide a rigorous test of the Color Glass Condensate (CGC), a model proposed to describe the high energy limit of Quantum Chromodynamics. In the CGC the average multiplicity of charged particles at midrapidity in p+A collisions depends logarithmically on the number of participants, $N_{part}$. In contrast, the Wounded Nucleon Model (WNM) of independent nucleon-nucleon scatterings, verified at RHIC energies, predicts that multiplicity in p+A depends linearly on $N_{part}$. We argue that for the first time, the dependence of mean multiplicity on $N_{part}$ in p+A collisions at LHC energies can single out a model of particle production, thus offering a stringent test of the CGC and the WNM. Based on this observation we propose a novel experimental test of color coherence in p+A collisions.