Solution of the RHIC HBT puzzle with Gaussian initial conditions

TL;DR

This paper demonstrates that using Gaussian initial conditions in hydrodynamic models effectively resolves the RHIC HBT puzzle by accurately describing key observables in heavy-ion collisions.

Contribution

It introduces Gaussian initial energy density profiles in hydrodynamic simulations, showing they can simultaneously fit spectra, flow, and HBT radii at RHIC.

Findings

Gaussian initial conditions improve fit to experimental data.

Early hydrodynamics start yields similar results to pre-equilibrium models.

Hydrodynamic description can be consistent with RHIC observations.

Abstract

It is argued that the consistent description of the transverse-momentum spectra, elliptic flow, and the HBT radii in the relativistic heavy-ion collisions studied at RHIC may be obtained within the hydrodynamic model if one uses the Gaussian profile for the initial energy density in the transverse plane. Moreover, we show that the results obtained in the scenario with an early start of hydrodynamics (at the proper time tau0 = 0.25 fm) are practically equivalent to the results obtained in the model where the hydrodynamics is preceded by the free-streaming stage of partons (in the proper time interval 0.25 fm < tau < 1 fm) which suddenly equilibrate and with the help of the Landau matching conditions are transformed into the hydrodynamic regime (at the proper time tau0 = 1 fm).