Components of the elliptic flow in Pb-Pb collisions at 2.76 TeV

TL;DR

This paper uses relativistic viscous hydrodynamics to analyze elliptic flow in Pb-Pb collisions at 2.76 TeV, showing good agreement with data and highlighting deviations at low transverse momentum due to non-thermalized particles.

Contribution

It demonstrates that hydrodynamic models with low shear viscosity can accurately describe elliptic flow data at LHC energies, and identifies the impact of jet fragmentation at low momenta.

Findings

Hydrodynamic model with η/s=0.08 fits ALICE data well.

Deviations at low pT suggest non-thermalized particle contributions.

Elliptic flow increases with collision centrality.

Abstract

We calculate the elliptic flow of charged particles in Pb-Pb collisions at 2.76 TeV in relativistic viscous hydrodynamics. The recent data of the ALICE Collaboration on the elliptic flow as function of the centrality can be very well described using the hydrodynamic expansion of a fluid with a small shear viscosity eta/s=0.08. The elliptic flow as function of the transverse momentum shows systematic deviations from a hydrodynamic behavior in the small momenta region pt<800MeV. It indicates that a non-negligible contribution of non-thermalized particles from jet fragmentation is present.