Soft heavy-ion physics from hydrodynamics with statistical hadronization - predictions for the Large Hadron Collider

TL;DR

This paper combines hydrodynamics and statistical hadronization to model relativistic heavy-ion collisions, providing predictions for LHC observables based on RHIC data and lattice QCD inputs.

Contribution

It introduces a comprehensive model merging hydrodynamics with statistical hadronization for LHC predictions, extending previous RHIC analyses with new initial conditions and equations of state.

Findings

The model satisfactorily describes RHIC soft hadronic observables.

Predictions show increased multiplicities and flow at higher initial temperatures for LHC.

Elliptic flow saturates while HBT radii grow with initial temperature.

Abstract

Hydrodynamics merged with single-freeze-out statistical hadronization is used to describe the midrapidity hadron production in relativistic heavy-ion collisions at the highest RHIC energies and to make predictions for the LHC. Thermodynamic properties of the quark-gluon plasma are taken from lattice simulations, at low temperatures the hadron-gas equation of state is used, while in the cross-over region an interpolation between the two equations of state is constructed. The initial condition for hydrodynamics is obtained from a Glauber profile for the entropy, with the initial central temperature Ti. The conditions obtained from the hydrodynamic expansion at the freeze-out temperature Tf are used as input for the thermal event generator THERMINATOR. Basic physical observables are obtained: the transverse-momentum spectra, the elliptic flow coefficient v2, and the HBT radii. The femtoscopic observables are evaluated with the help of the two-particle method which accounts for the resonance decays and Coulomb final-state interactions. The problem of a simultaneous description of all discussed observables is addressed, with the conclusion that at the highest RHIC energies our approach gives a quite satisfactory global description of soft hadronic observables. Some discrepancies may be attributed to the absence of the final-state elastic interactions among hadrons. Extrapolating Ti to higher values allows for global predictions for soft hadronic physics at the LHC. We test Ti=400, 450, and 500 MeV, and observe the expected growth of particle multiplicities and the increase of the flow, resulting in smaller slopes of the pT-spectra. The elliptic flow of pions exhibits saturation, with v2 remaining practically constant, while the HBT radii increase moderately with Ti.