Vortex rings in heavy-ion collisions at energies $\sqrt{s_{NN}}=$ 3--30 GeV and possibility of their observation

TL;DR

This paper investigates vortex ring formations in heavy-ion collisions at energies 3-30 GeV using three-fluid dynamics, proposing their potential detection through specific observables and discussing their significance for understanding early collision stages.

Contribution

It introduces the formation of vortex rings in ultra-central Au+Au collisions at energies above 4 GeV and explores their detectability via the ring observable $R_ extLambda$, linking them to early collision dynamics.

Findings

Vortex rings form at forward and backward rapidities in collisions above 4 GeV.

The ring observable $R_ extLambda$ can detect vortex rings at 0.5-1.5 ext% level in certain rapidity ranges.

Stronger signals are expected at forward/backward rapidities.

Abstract

The ring structures that appear in Au+Au collisions at collision energies $\sqrt{s_{NN}}=$ 3 -- 30 GeV are studied. The calculations are performed within the model of three-fluid dynamics. It is demonstrated that a pare of vortex rings are formed, one at forward and another at backward rapidities, in ultra-central Au+Au collisions at $\sqrt{s_{NN}}>$ 4 GeV. The vortex rings carry information about early stage of the collision, in particular about the stopping of baryons. It is shown that these rings can be detected by measuring the ring observable $R_\Lambda$ even in rapidity range $0<y<0.5$ (or $-0.5<y<0$) on the level of 0.5--1.5\% at $\sqrt{s_{NN}}=$ 5 -- 20 GeV. At forward/backward rapidities, the $R_\Lambda$ signal is expected to be stronger. Possibility of observation of the vortex-ring signal against background of non-collective transverse polarization is discussed.