Comparing matching prescriptions between pre-equilibrium and hydrodynamic models in high-energy nuclear collisions

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Main Authors: Borghini, Nicolas, Krupczak, Renata, Roch, Hendrik
Format: Preprint
Published: 2024
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author Borghini, Nicolas
Krupczak, Renata
Roch, Hendrik
author_facet Borghini, Nicolas
Krupczak, Renata
Roch, Hendrik
contents State-of-the-art simulations of high-energy nuclear collisions rely on hybrid setups, involving in particular a pre-equilibrium stage to let the system evolve from a far-from-equilibrium initial condition towards a near-equilibrated state after which fluid dynamics can be applied meaningfully. A known issue is the mismatch between the equation of state in the fluid-dynamical evolution and the effective one in the previous stage, which leads to discontinuities at the interface between the two models. Here we introduce a new matching prescription at this interface, based on the entropy, and we compare it with the standard one relying on local energy conservation. We study the behavior of various quantities at the switching time between the models and investigate a number of final-state hadronic observables. For the latter, we show that they are not modified significantly by the choice of matching prescription, provided an appropriate normalization is chosen for the initial state. In turn, our approach reduces sizeably the ratio of bulk over thermodynamic pressure at the beginning of the fluid-dynamical stage.
format Preprint
id arxiv_https___arxiv_org_abs_2407_10634
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Comparing matching prescriptions between pre-equilibrium and hydrodynamic models in high-energy nuclear collisions
Borghini, Nicolas
Krupczak, Renata
Roch, Hendrik
Nuclear Theory
High Energy Physics - Phenomenology
State-of-the-art simulations of high-energy nuclear collisions rely on hybrid setups, involving in particular a pre-equilibrium stage to let the system evolve from a far-from-equilibrium initial condition towards a near-equilibrated state after which fluid dynamics can be applied meaningfully. A known issue is the mismatch between the equation of state in the fluid-dynamical evolution and the effective one in the previous stage, which leads to discontinuities at the interface between the two models. Here we introduce a new matching prescription at this interface, based on the entropy, and we compare it with the standard one relying on local energy conservation. We study the behavior of various quantities at the switching time between the models and investigate a number of final-state hadronic observables. For the latter, we show that they are not modified significantly by the choice of matching prescription, provided an appropriate normalization is chosen for the initial state. In turn, our approach reduces sizeably the ratio of bulk over thermodynamic pressure at the beginning of the fluid-dynamical stage.
title Comparing matching prescriptions between pre-equilibrium and hydrodynamic models in high-energy nuclear collisions
topic Nuclear Theory
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2407.10634