Transverse spherocity dependence of azimuthal anisotropy in heavy-ion collisions at the LHC using a multi-phase transport model

TL;DR

This study introduces the use of transverse spherocity in heavy-ion collisions at the LHC to distinguish event geometries and their impact on azimuthal anisotropy, revealing that spherocity effectively separates different flow contributions.

Contribution

First implementation of transverse spherocity in heavy-ion collisions using a multi-phase transport model to analyze azimuthal anisotropy.

Findings

High-spherocity events have nearly zero elliptic flow.

Low-spherocity events significantly contribute to overall elliptic flow.

Spherocity effectively differentiates event topologies based on geometrical shapes.

Abstract

One of the event shape observables, the transverse spherocity ($S_0$), has been studied successfully in small collision systems such as proton-proton collisions at the LHC as a tool to separate jetty and isotropic events. It has a unique capability to distinguish events based on their geometrical shapes. In this work, we report the first implementation of transverse spherocity in heavy-ion collisions using a multi-phase transport model (AMPT). We have performed an extensive study of azimuthal anisotropy of charged particles produced in heavy-ion collisions as a function of transverse spherocity ($S_0$). We have followed the two-particle correlation (2PC) method to estimate the elliptic flow ($v_2$) in different centrality classes in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV for high-$S_0$, $S_0$-integrated and low-$S_0$ events. We found that transverse spherocity successfully differentiates heavy-ion collisions event topology based on their geometrical shapes, i.e., high and low values of spherocity. The high-$S_0$ events have nearly zero elliptic flow, while the low-$S_0$ events contribute significantly to the elliptic flow of spherocity-integrated events.