Based on the model of three-fluid dynamics (3FD), the global $\mathrm{\Lambda }$ polarization ($P_{\mathrm{\Lambda }}$) is calculated in $\mathrm{Au}+\mathrm{Au}$ collisions at 3 $\le \sqrt{s_{NN}}\le$ 9 GeV, in which high baryon density is achieved. Various contributions to $P_{\mathrm{\Lambda }}$ are considered: those from the thermal vorticity, meson field, thermal shear, and spin-Hall effect. Feed-down from higher-lying resonances is also taken into account. The results are compared with available data. Special attention is payed to the collision energies of $\sqrt{s_{NN}}=3$, 3.2, 3.5, 3.9, and 4.5 GeV, for which a thorough scan of the energy, rapidity, and centrality dependence of $P_{\mathrm{\Lambda }}$ is performed. The results for 3 GeV reasonably well reproduce the corresponding STAR data. While the results at $\sqrt{s_{NN}}=3.2$, 3.5, 3.9, and 4.5 GeV can be considered as predictions for results of measurements within the STAR fixed-target (STAR-FXT) program that are expected in the nearest future. It is predicted that a broad maximum of $P_{\mathrm{\Lambda }}$ is reached at $\sqrt{s_{NN}}\approx 3$–3.9 GeV, exact position of which depends on the centrality and width of the midrapidity range of observation. Impact of the meson-field, thermal-shear, and spin-Hall-effect contributions to $P_{\mathrm{\Lambda }}$ is also studied.

Close

PrevNext

View figure in article

• Hydrodynamic models
• Nuclear reactions
• Polarization phenomena
• Relativistic heavy-ion collisions