Multiplicity dependence of charged-particle production in pp, p-Pb, Xe-Xe and Pb-Pb collisions at the LHC

TL;DR

This paper presents detailed measurements of charged-particle multiplicity and transverse momentum spectra across various collision systems and energies at the LHC, providing crucial data for testing and tuning theoretical models of particle production.

Contribution

It introduces a novel two-dimensional unfolding method to analyze the correlation between transverse momentum and multiplicity in different collision systems and energies.

Findings

Multiplicity distributions are characterized across systems and energies.

The correlation between $p_T$ and multiplicity is sharply defined.

Results serve as benchmarks for tuning Monte Carlo models.

Abstract

Multiplicity ($N_{\rm ch}$) distributions and transverse momentum ($p_{\rm T}$) spectra of inclusive primary charged particles in the kinematic range of $|\eta| < 0.8$ and 0.15 GeV/$c$ $< p_{T} <$ 10 GeV/$c$ are reported for pp, p-Pb, Xe-Xe and Pb-Pb collisions at centre-of-mass energies per nucleon pair ranging from $\sqrt{s_{\rm NN}} = 2.76$ TeV up to $13$ TeV. A sequential two-dimensional unfolding procedure is used to extract the correlation between the transverse momentum of primary charged particles and the charged-particle multiplicity of the corresponding collision. This correlation sharply characterises important features of the final state of a collision and, therefore, can be used as a stringent test of theoretical models. The multiplicity distributions as well as the mean and standard deviation derived from the $p_{\rm T}$ spectra are compared to state-of-the-art model predictions. Providing these fundamental observables of bulk particle production consistently across a wide range of collision energies and system sizes can serve as an important input for tuning Monte Carlo event generators.