Disentangling Soft and Hard Hadron Yields in PbPb Collisions at $\sqrt{s_{NN}}$ = 2.76 ATeV

TL;DR

This paper models charged hadron yields in PbPb collisions at 2.76 TeV by separating soft and hard processes, using Tsallis distributions to describe spectra and azimuthal anisotropy, revealing that anisotropy decreases with collision centrality.

Contribution

It introduces a novel model distinguishing soft and hard hadron production in heavy-ion collisions using Tsallis distributions, and analytically describes spectra and azimuthal anisotropy.

Findings

Tsallis distribution approximates pion spectra for $p_T \, \geq \, 4$ GeV/c.

Azimuthal anisotropy decreases with increasing collision centrality.

Model successfully describes both spectra and $v_2$ in PbPb collisions.

Abstract

We demonstrate that charged pion spectra in central and peripheral PbPb collisions at $\sqrt{s}$ = 2.76 ATeV obtained via perturbative quantum chromodynamics improved parton model calculations [17] can be approximated by the Tsallis distribution for transverse momenta $p_T \geq$ 4 GeV/c. Then, we propose a model in which, hadrons produced in heavy-ion collisions stem either from "soft" or "hard" processes, and are distributed according to the Tsallis distribution in both types of yields. We describe transverse spectra as well as azimuthal anisotropy ($v_2$) of charged hadrons stemming from various centrality PbPb collisions at $\sqrt{s}$ = 2.76 ATeV [40,41,42] analytically. In addition, we find that the anisotropy decreases for more central collisions.