Light-nuclei production in heavy-ion collisions within a thermodynamical approach

TL;DR

This study uses a thermodynamical approach within a hydrodynamical simulation framework to model light-nuclei production in heavy-ion collisions, achieving reasonable agreement with experimental data across various energies and nuclei types.

Contribution

It introduces an updated simulation method that treats light nuclei within a thermodynamical framework, incorporating a late freeze-out parameter to better reproduce experimental observables.

Findings

Reasonable reproduction of light nuclei yields and ratios across energies.

Directed flow of light nuclei requires explicit afterburner treatment.

Room for medium effects in light nuclei production remains.

Abstract

We present results of simulations of light-nuclei production in relativistic heavy-ion collisions within updated Three-fluid Hydrodynamics-based Event Simulator Extended by UrQMD (Ultra-relativistic Quantum Molecular Dynamics) final State interactions (THESEUS). The simulations were performed for Pb+Pb and Au+Au collisions in the collision energy range of $\sqrt{s_{NN}}=$ 6.4--19.6 GeV. The light-nuclei production is treated within the thermodynamical approach on equal basis with hadrons. The only additional parameter related to the light nuclei is the energy density of late freeze-out that imitates afterburner stage of the collision because the light nuclei do not participate in the UrQMD evolution. This parameter is fixed from the condition of the best reproduction of the proton transverse-momentum spectrum after the UrQMD afterburner by that at the late freeze-out. The updated THESEUS results in not perfect, but a reasonable reproduction of data on bulk observables of the light nuclei, especially their functional dependence on the collision energy and light-nucleus mass. Various ratios, $d/p$, $t/p$, $t/d$, and $N(t)\times N(p)/N^2(d)$, are also considered. The directed flow of light nuclei turns out to be more involved. Apparently, it requires explicit treatment of the afterburner evolution of light nuclei that violates the kinetic equilibrium. Imperfect reproduction of the light-nuclei data leaves room for medium effects in produced light nuclei.