Event topology and global observables in heavy-ion collisions at the Large Hadron Collider

TL;DR

This paper investigates how event shape observable transverse spherocity correlates with global properties like energy density and freeze-out conditions in heavy-ion collisions at the LHC, using AMPT simulations.

Contribution

It demonstrates the feasibility of using transverse spherocity to study global observables in Pb-Pb collisions at LHC energies, highlighting its potential in heavy-ion physics.

Findings

Transverse spherocity correlates with energy density and medium properties.

Event topology influences global observable measurements.

Feasibility of spherocity-based analysis in heavy-ion collisions is confirmed.

Abstract

Particle production and event topology are very strongly correlated in high-energy hadronic and nuclear collisions. Event topology is decided by the underlying particle production dynamics and medium effects. Transverse spherocity is an event shape observable, which has been used in pp and heavy-ion collisions to separate the events based on their geometrical shapes. It has the unique capability to distinguish between jetty and isotropic events. In this work, we have implemented transverse spherocity in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV using A Multi-Phase Transport Model (AMPT). While awaiting for experimental explorations, we perform a feasibility study of dependence of transverse spherocity on some of the global observables in heavy-ion collisions at the Large Hadron Collider energies. These global observables include the Bjorken energy density ($\epsilon_{\rm B_j}$), speed of sound ($c_{\rm s}^2$) in the medium and the kinetic freeze-out properties for different collision centralities. The present study reveals about the usefulness of event topology dependent measurements in heavy-ion collisions in contrast to proton-proton collisions.