Space-time regions of high baryon density and baryon stopping in heavy-ion collisions

TL;DR

This study compares the space-time volume of high baryon density regions in heavy-ion collisions using three-fluid dynamics and microscopic transport models, revealing differences in baryon stopping and optimal energy ranges for dense matter formation.

Contribution

It introduces a comparative analysis of four-volume calculations for high baryon density regions in heavy-ion collisions using 3FD and JAM models, highlighting differences in baryon stopping and density dependence on collision energy.

Findings

3FD model shows stronger baryon stopping than JAM.

Four-volume with baryon density > 3n0 decreases monotonically with energy.

Optimal energy range for high baryon densities is 3.2--8 GeV.

Abstract

Four-volumes ($V_4=$ spatial-3-volume$\times$lifetime) are calculated within the model of three-fluid dynamics (3FD) and compared with those of the the JET AA Microscopic Transport Model (JAM). The calculations are performed for central Au+Au collisions at energies $\sqrt{s_{NN}}=$ 3 -- 19.6 GeV. These $V_4$ indicate optimal collision-energy ranges for realizing macroscopic high baryon-density matter. It is found that the 3FD four-volumes noticeably exceed those in the JAM, which indicates a stronger baryon stopping in the 3FD model as compared to that JAM. It is argued that this difference in the baryon stopping correlates with stiffness of the EoS implemented in these models. Contrary to JAM, the four-volume, where a baryon density ($n_B$) exceeds three times the normal nuclear density ($n_0$), does not exhibit a maximum as a function of $\sqrt{s_{NN}}$. It decreases monotonically with increasing $\sqrt{s_{NN}}$, remaining at a fairly macroscopic level (i.e. $V_4\geq 5.5^4$ fm$^4$/c). For higher baryon densities, $V_4$ exhibits maxima in its dependence on $\sqrt{s_{NN}}$. The optimal energy range for densities $n_B/n_0>$ 4 is located at $\sqrt{s_{NN}}=$ 3.2--8 GeV. Even for $n_B/n_0>$ 6, the four-volume remains quite macroscopic ($V_4\geq 4^4$ fm$^4$/c) at $\sqrt{s_{NN}}=$ 4.5--9 GeV contrary to the JAM.