Event-shape- and multiplicity-dependent identified particle production in pp collisions at 13 TeV with ALICE at the LHC

TL;DR

This paper investigates how event shapes and multiplicity influence identified particle production in proton-proton collisions at 13 TeV, aiming to distinguish collective effects from well-understood physics processes.

Contribution

It provides a comprehensive analysis of particle spectra and ratios as functions of event multiplicity, energy, and shape, enhancing understanding of particle production mechanisms in pp collisions.

Findings

Particle spectra vary with event shape and multiplicity.

Particle ratios show dependence on event characteristics.

Results are compared to QCD-inspired models.

Abstract

Multiplicity-dependent measurements of identified particle production led to the discovery of collective-like behavior in pp collisions at the LHC. Better understanding of the effects attributed to well-understood physics, like multiple hard scatterings, is required to establish whether this behaviour is truly collective in origin. Experimentally, those effects can be controlled using event shapes, like transverse spherocity, which allows the classification of pp collisions either as jetty or isotropic events. The transverse momentum ($p_{\rm T}$) spectra of light-flavor hadrons in pp collisions measured over a broad range provide important input to study particle production mechanisms in the soft and hard scattering regimes of the QCD. In this work, they are used to perform a comprehensive study as a function of the event multiplicity, collision energy, and event shapes. The proton-to-pion and kaon-to-pion particle ratios as a function of $p_{\rm T}$ are also reported and the results compared to QCD-inspired models.