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

## TL;DR

This paper uses hydrodynamic attractors to connect initial energy states with particle production in nuclear collisions, providing a universal description of particle yields and insights into quark-gluon plasma properties.

## Contribution

It introduces a general relation between initial energy and particle multiplicities using hydrodynamic attractors, enhancing understanding of pre-equilibrium dynamics in nuclear collisions.

## Key findings

- Universal centrality dependence of charged particle yields explained
- Estimated initial energy density of far-from-equilibrium state
- Constraints on non-equilibrium properties of quark-gluon plasma

## 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.