Rapid hydrodynamic expansion in relativistic heavy-ion collisions

Abstract

Hydrodynamic expansion of the hot fireball created in relativistic Au-Au collisions at √ s = 200GeV in 3 + 1-dimensions is studied. We obtain a simultaneous, satisfactory description of the transverse momentum spectra, elliptic flow and pion correlation radii for different collision centralities and different rapidities. Early initial time of the evolution is required to reproduce the interferometry data, which provides a strong indication of the early onset of collectivity. We can also constraint the shape of the initial energy density in the beam direction, with a relatively high initial energy density at the center of the fireball.

Interferometric signatures of the temperature dependence of the specific shear viscosity in heavy-ion collisions

“…Our findings are qualitatively supported by the work [28] (whose authors, like us, used the source variances method) where it was found that an increase in the Knudsen number (or, equivalently, η/s) resulted in a decrease in R 2 o . The purpose of the present work is not a realistic comparison with experimental data which, as done in [15,16], would require a simultaneous tuning of several additional parameters (see also Ref. [29]).…”

“…Studies such as [15,16] have explored the sensitivity of the HBT radii to shear viscosity using constant (Tindependent) η/s and varying that constant. Different from our approach here, when changing η/s they also changed other hydrodynamic parameters to ensure that not only the normalization but also the slope of the p Tspectra was held fixed.…”

“…To save time and effort, we employ for this pioneering study the shortcut of calculating the HBT radii from the source variances of the emission function [10][11][12][13] for directly emitted pions only, instead of performing a 3-D Gaussian fit to the correlation function including all resonance decays [13][14][15][16]. This approximation, which holds exactly only for Gaussian sources [12], is known to be sufficient to discern qualitative features of the HBT radii and their K T dependences, although it is not accurate enough for quantitative comparisons with experimental data [17].…”

Photon production from a nonequilibrium quark-gluon plasma

“…The parameters of the longitudinal profile (54) were fitted to reproduce the pseudorapidity distribution of charged particles with the results being ∆ς = 2.5 and σ ς = 1.4. The shift in rapidity is calculated according to the formula [52] …”

The realistic QCD equation of state in relativistic heavy-ion collisions and the early Universe

“…The results of the hadron-gas model at lower temperatures are combined with the lattice results at higher temperatures in the thermody-namically consistent way described in [9]. However, the most attractive feature of our EOS is the fact that it was successfully implemented in 2+1 [10] and 3+1 [11] hydrodynamic codes describing heavy-ion collisions. Thus, in our case the knowledge from heavy-ion physics is transferred directly to cosmology.…”