Update of the three-fluid hydrodynamics-based event simulator: Light-nuclei production in heavy-ion collisions

We present an update of the event generator based on the three-fluid dynamics (3fd), complemented by Ultrarelativistic Quantum Molecular Dynamics (urqmd) for the late stage of the nuclear collision—the Three-fluid Hydrodynamics-based Event Simulator Extended by urqmd final State interactions (theseus). Two modifications are introduced. The theseus table of hadronic resonances is made consistent with that of the underlying 3fd model. The main modification is that the generator is extended to simulate the light-nuclei production in relativistic heavy-ion collisions, on an equal basis with hadrons. These modifications are illustrated by applications to the description of available experimental data. The first run of the updated generator revealed a good reproduction of the NA49 data on the light nuclei. The reproduction is achieved without any extra parameters, while the coalescence approach in 3fd requires special tuning of the coalescence coefficients for each light nucleus separately.

Figure 1

Rapidity distribution of (a) protons, of (b) positive pions (excluding the weak-decay feed-down), of (c) positive kaons, and of (d) negative kaons in central ($b=2$ fm) $\text{Au}+\text{Au}$ collisions at a collision energy of $\sqrt{s_{NN}}=9.2\mathrm{GeV}$ calculated with the crossover EoS [11]: the 3fd result (short-dashed line), the result of theseus-v2 without urqmd (long-dashed line), and the result of theseus-v2 with urqmd (solid line). Experimental data are from the STAR collaboration [16].

Figure 2

Rapidity distributions of deuterons $d$, tritons $t$, ${}^3\mathrm{He}$, ${}^4\mathrm{He}$, and protons in central ($b=2$ fm) $\text{Au}+\text{Au}$ collisions at a collision energy of $\sqrt{s_{NN}}=2.7\mathrm{GeV}$ ($E_{\mathrm{lab}}=2A\mathrm{GeV}$) within the crossover scenario [11] calculated by means of the 3fd with coalescence (short-dashed line), the theseus-v2 without recalculation of the baryon chemical potential and hence without baryon charge conservation (dotted line), theseus-v2 without excited states of ${}^4\mathrm{He}$ (long-dashed line), and full theseus-v2 (solid line). The proton data are from Ref. [21].

Figure 3

The same as in Fig. 2 but for central ($b=3$ fm) $\text{Pb}+\text{Pb}$ collisions at a collision energy of $E_{\mathrm{lab}}=20A\mathrm{GeV}$. Experimental data are from the NA49 collaboration [22].