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.

arXiv commentV3: 6 pages, 5 figures. Published version

References in corpus (48)

• Experimental and Theoretical Challenges in the Search for the Quark Gluon Plasma: The STAR Collaboration's Critical Assessment of the Evidence from RHIC Collisions
• Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration
• Microscopic Models for Ultrarelativistic Heavy Ion Collisions
• Relativistic Hadron-Hadron Collisions in the Ultra-Relativistic Quantum Molecular Dynamics Model (UrQMD)
• Global $\Lambda$ hyperon polarization in nuclear collisions: evidence for the most vortical fluid
• Globally Polarized Quark-gluon Plasma in Non-central A+A Collisions
• Modelling the many-body dynamics of heavy ion collisions: Present status and future perspective
• Fully integrated transport approach to heavy ion reactions with an intermediate hydrodynamic stage
• Relativistic distribution function for particles with spin at local thermodynamical equilibrium
• Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR
• Global polarization of $\Lambda$ hyperons in Au+Au collisions at $\sqrt{s_{{}_{NN}}}$ = 200 GeV
• The High-Acceptance Dielectron Spectrometer HADES
• Global hyperon polarization at local thermodynamic equilibrium with vorticity, magnetic field and feed-down
• Rotating quark-gluon plasma in relativistic heavy ion collisions
• Study of Lambda polarization in relativistic nuclear collisions at sqrt{s}_NN = 7.7-200 GeV
• Vorticity in Heavy-Ion Collisions
• Global $\Lambda$ polarization in heavy-ion collisions from a transport model
• Polarization and Vorticity in the Quark Gluon Plasma
• Polarization of massive fermions in a vortical fluid
• Probing vorticity structure in heavy-ion collisions by local $\Lambda$ polarization
• Thermal vorticity and spin polarization in heavy-ion collisions
• Lambda hyperon polarization in relativistic heavy ion collisions from the chiral kinetic approach
• Anomalous chiral transports and spin polarization in heavy-ion collisions
• Global polarization of $\Xi$ and $\Omega$ hyperons in Au+Au collisions at $\sqrt{s_{{}_{NN}}}$ = 200 GeV
• Magnetic Field Induced Polarization Difference between Hyperons and Anti-hyperons
• Local spin polarization in high energy heavy ion collisions
• A hydrodynamic study of hyperon spin polarization in relativistic heavy ion collisions
• Vorticity in low-energy heavy-ion collisions
• Feed-down effect on $\Lambda$ spin polarization
• Polarization transfer in hyperon decays and its effect in relativistic nuclear collisions
• Ideal spin hydrodynamics from Wigner function approach
• Estimates of hyperon polarization in heavy-ion collisions at collision energies $\sqrt{s_{NN}}=$ 4--40 GeV
• Different space-time freeze-out picture -- an explanation of different $\Lambda$ and $\bar{\Lambda }$ polarization?
• $\Lambda$ and $\bar{\Lambda }$ spin interaction with meson fields generated by the baryon current in high energy nuclear collisions
• Unified Description of Nuclear Stopping in Central Heavy-ion Collision from 10$A$ MeV to 1.2$A$ GeV
• Vorticity and Spin Polarization in Heavy Ion Collisions: Transport Models
• Global $\Lambda$ polarization in moderately relativistic nuclear collisions
• Vorticity and Spin Polarization --- A Theoretical Perspective
• Correlation between global polarization, angular momentum and flow in heavy-ion collisions
• Investigating different $\Lambda$ and $\bar{\Lambda }$ polarizations in relativistic heavy-ion collisions
• Fluid Dynamics Study of the $\Lambda$ Polarization for Au+Au Collisions at $\sqrt{s_{NN}}=200$ GeV
• Dynamical exploring the QCD matter at finite temperatures and densities-a short review
• STAR Results from Au + Au Fixed-Target Collisions at sqrt(s_NN) = 4.5 GeV
• A study of $\Lambda$ and $\bar{\Lambda }$ polarization splitting by meson field in PICR hydrodynamic model
• 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
• Vorticity and Polarization in Heavy Ion Collisions: Hydrodynamic Models
• Chiral anomaly in non-relativistic systems: Berry curvature and chiral kinetic theory

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