Anisotropy Scaling Functions in Heavy-Ion Collisions: Insights into the `Ultra-Central Flow Puzzle' and Constraints on Transport Coefficients and Nuclear Deformation

Author:

Roy A. Lacey

Keyword:

Nuclear Experiment, Nuclear Experiment (nucl-ex), High Energy Physics - Experiment (hep-ex), Nuclear Theory (nucl-th)

journal:

date:

2024-02-14 00:00:00

Abstract

Anisotropy scaling functions, derived from extensive measurements of transverse momentum- and centrality-dependent anisotropy coefficients $v_2(p_T,\text{cent})$ and $v_3(p_T,\text{cent})$ in Pb+Pb collisions at 5.02 and 2.76 TeV, and Xe+Xe collisions at 5.44 TeV at the LHC, shed light on the 'ultra-central flow puzzle'. These functions amalgamate diverse measurements into a unified curve, elucidating anisotropy attenuation across the full $p_T$ and centrality range and unveiling dependencies on key factors including initial-state eccentricities ($\varepsilon_{n}$), dimensionless size ($\mathbb{R}$), radial flow, viscous correction to the thermal distribution function ($\delta_f$), the medium's stopping power ($\hat{q}$), and specific shear viscosity ($\eta/s$). Their analysis provides distinct insights into transport coefficients and nucleus deformation constraints.

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