Fluctuations of anisotropic flow from the finite number of rescatterings in a two-dimensional massless transport model

Hendrik Roch,Nicolas Borghini

doi:10.1140/epjc/s10052-021-09147-z

Hendrik Roch, Nicolas Borghini

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https://doi.org/10.1140/epjc/s10052-021-09147-z

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Abstract

We investigate the fluctuations of anisotropic transverse flow due to the finite number of scatterings in a two-dimensional system of massless particles. Using a set of initial geometries from a Monte Carlo Glauber model, we study how flow coefficients fluctuate about their mean value at the corresponding eccentricity, for several values of the scattering cross section. We also show how the distributions of the second and third event planes of anisotropic flow about the corresponding participant plane in the initial geometry evolve as a function of the mean number of scatterings in the system.

Highlights

Anisotropic flow is one of the most prominent observables in heavy-ion collision experiments, especially at high energies
We show how the distributions of the second and third event planes of anisotropic flow about the corresponding participant plane in the initial geometry evolve as a function of the mean number of scatterings in the system
We focus on the fluctuations of the anisotropic flow harmonics that arise due to the finite number of rescatterings Nresc. per particle in a kinetic-transport description of the system

Summary

Introduction

Anisotropic flow is one of the most prominent observables in heavy-ion collision experiments, especially at high energies. The signal, a modulation in the transverse emission pattern of particles, is believed to be largely due to the lack of cylindrical symmetry of the initial geometry, which is converted by rescatterings into an anisotropy in momentum space [1,2,3]. The random positions at the instant of the collision of the nucleons, and of the underlying quarks and gluons with their associated color fields, result in an inhomogeneous energy-density profile in the overlap zone. Restricting oneself to the transverse geometry of that zone, described by polar coordinates (r, θ ), its azimuthal asymmetries are usually characterized by eccentricities [4,5,6]: εn ein n ≡− r neinθ rn (1). The anisotropies of the transverse momentum distribution of particles are quantified by the successive coefficients of a Fourier series [7]: vn ein n ≡ einφp ,

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