Lambda polarization in ${}^{108}$Ag +${}^{108}$Ag and ${}^{197}$Au +${}^{197}$Au collisions around a few GeV

Abstract

Within the framework of Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model, we extract the global spin polarization of $\Lambda$ hyperon in ${}^{108}$Ag + ${}^{108}$Ag and ${}^{197}$Au + ${}^{197}$Au collisions at $\sqrt{s_{\mathrm{NN}}}=2.42-62.4$ GeV. We use two different approaches to calculate the $\Lambda$ polarization $P_y$: approach I is based on equilibrium assumption so that $P_y$ is determined by thermal vorticity and approach II assumes a proportional relation between $P_y$ and the system's angular momentum in $\Lambda$'s rest frame. We find that both approaches can describe the experimental data at low energies around a few GeV but only approach I describes well also higher-energy data. This suggests that at higher energies the relativistic effect plays an important role. After taking into such effect properly, the relativity-improved approach II can describe the higher-energy data as well.

V3: 6 pages, 5 figures. Published version

References in corpus (12)

• Fully integrated transport approach to heavy ion reactions with an intermediate hydrodynamic stage
• Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR
• Lambda hyperon polarization in relativistic heavy ion collisions from the chiral kinetic approach
• Global polarization of $\Xi$ and $\Omega$ hyperons in Au+Au collisions at $\sqrt{s_{{}_{NN}}}$ = 200 GeV
• A hydrodynamic study of hyperon spin polarization in relativistic heavy ion collisions
• Ideal spin hydrodynamics from Wigner function approach
• Different space-time freeze-out picture -- an explanation of different $\Lambda$ and $\bar{\Lambda }$ polarization?
• Global $\Lambda$ polarization in moderately relativistic nuclear collisions
• Dynamical exploring the QCD matter at finite temperatures and densities-a short review
• Electrostatic-lenses position-sensitive TOF MCP detector for beam diagnostics and new scheme for mass measurements at HIAF
• Thermodynamics of the system of massive Dirac fermions in a uniform magnetic field
• Chiral anomaly in non-relativistic systems: Berry curvature and chiral kinetic theory

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