Particle production as a function of system size and underlying-event activity measured with ALICE at the LHC

TL;DR

This study investigates how particle production varies with system size and event activity in high-energy collisions at the LHC, using ALICE data to analyze correlations between transverse momentum spectra and multiplicity across different collision types and energies.

Contribution

It introduces a novel analysis of underlying-event activity as a multiplicity estimator to separate production mechanisms in small and large collision systems.

Findings

Particle production depends on system size and event activity.

Underlying-event activity helps distinguish between soft and hard processes.

Results are consistent across different collision energies and systems.

Abstract

High-energy collisions in ALICE allow for the study of soft and hard QCD particle production. The correlation between transverse momentum spectra and event multiplicity is a sensitive observable providing insights into the different production mechanisms. In these proceedings we report on this observable for unidentified charged-particles, obtained using a 2d-unfolding procedure. Particle production is compared at different collision energies, as well as for pp, p--Pb and Pb--Pb collisions at the same energy. In order to understand the role of autocorrelations in small systems, it was proposed to exploit the usage of the underlying event as a multiplicity estimator to factorize the hardest and the softer components of the events. For this purpose, in these proceedings the charged particle transverse momentum distributions are also presented as a function of underlying-event activity in pp collisions.