Higher order anisotropies in the Buda-Lund model: Disentangling flow and density field anisotropies

TL;DR

This paper extends the Buda-Lund hydro model to include higher order anisotropies, allowing for a detailed analysis of flow coefficients and HBT radii oscillations caused by event-by-event shape fluctuations.

Contribution

The paper introduces a multipole anisotropy extension to the Buda-Lund model, enabling disentangling flow and density field anisotropies in heavy-ion collisions.

Findings

Multipole anisotropies lead to measurable momentum-space anisotropies.

Flow coefficients and HBT radii oscillations are quantitatively described.

Event-by-event shape fluctuations impact observable anisotropies.

Abstract

The Buda-Lund hydro model describes an expanding ellipsoidal fireball, and fits the observed elliptic flow and oscillating HBT radii successfully. Due to fluctuations in energy depositions, the fireball shape however fluctuates on an event-by-event basis. The transverse plane asymmetry can be translated into a series of multipole anisotropy coefficients. These anisotropies then result in measurable momentum-space anisotropies, to be measured with respect to their respective symmetry planes. In this paper we detail an extension of the Buda-Lund model to multipole anisotropies and investigate the resulting flow coefficients and oscillations of HBT radii.