Initial conditions, equations of state and final state in hydrodynamics

TL;DR

This paper explores how different initial conditions and equations of state in hydrodynamical models can produce identical final hadronic states, highlighting the need for penetrating probes to distinguish initial dynamics.

Contribution

It demonstrates that hadronic observables alone cannot uniquely determine initial conditions or equations of state in hydrodynamics, emphasizing the importance of penetrating probes.

Findings

Different initial conditions can lead to the same final state.

Equations of state variations do not alter the final hadronic observables.

Penetrating probes are necessary to infer initial conditions.

Abstract

In this paper we present properties of relativistic and non-relativistic perfect hydrodynamical models. In particular we show illustrations of the fact that different initial conditions and equations of state can lead to the same hadronic final state. This means that alone from the hadronic observables one cannot determine either of the above, one needs for example penetrating probes that inherit their properties from each timeslice of the evolution of the fireball.