Global Λ polarization in heavy-ion collisions from a transport model

2017/04/30 by Hui Li, Long-Gang Pang, Qun Wang +1 · 1 citation
Physics and Astronomy · #nucl-th

paper · pdf · doi:10.1103/physrevc.96.054908

published as Phys. Rev. C 96, 054908 (2017) · RevTex 4-1, 7 pages, 6 figures, to appear in Phys. Rev. C

arxiv created 2017/11/06 · arxiv updated 2017/12/01

Abstract

The polarizations of Λ and Λ hyperons are important quantities in extracting the fluid vorticity of the strongly coupled quark gluon plasma and the magnitude of the magnetic field created in off-central heavy-ion collisions, through the spin-vorticity and spin-magnetic coupling. We computed the energy dependence of the global Λ polarization in off-central Au+Au collisions in the energy range √s_NN=7.7-200 GeV using a multiphase transport model. The observed polarizations with two different impact parameters agree quantitatively with recent STAR measurements. The energy dependence of the global Λ polarization is decomposed as energy dependence of the Λ distribution at hadronization and the space-time distribution of the fluid-vorticity field. The visualization of both the Λ distribution and the fluid-vorticity field show a smaller tilt at higher collisional energies, which indicates that the smaller global polarization at higher collisional energies is caused by a smaller angular momentum deposition at midrapidity.

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