Hydrodynamic attractors, initial state energy and particle production in relativistic nuclear collisions

Abstract

We exploit the concept of hydrodynamic attractors to establish a general relation between the initial state energy and the produced particle multiplicities in high-energy nuclear collisions. When combined with an ab initio model of energy deposition, the entropy production during the pre-equilibrium phase naturally explains the universal centrality dependence of the measured charged particle yields in nucleus-nucleus collisions. We further estimate the energy density of the far-from-equilibrium initial state and discuss how our results can be used to constrain non-equilibrium properties of the quark-gluon plasma.

Comments: 7 pages, 3 figures; v2: minor corrections, published version, plot scripts and data shown in figures are available at https://doi.org/10.4119/unibi/2939684 v3: included supplemental material