Hyperon polarization and its relation with directed flow in high-energy nuclear collisions

摘要

We investigate hyperon polarization and its relation with the directed flow of quark-gluon plasma (QGP) in noncentral Au + Au collisions at root sNN = 27 GeV. A modified three-dimensional Glauber model is developed and coupled to a (3 + 1)-dimensional viscous hydrodynamic evolution of the QGP. Within this framework, we obtain a satisfactory simultaneous description of the directed flow of identified particles and A polarization, and we show a sensitivity of polarization to both the tilted geometry and the longitudinal flow profile of the QGP. A nonmonotonic transverse momentum dependence of the A polarization is found in our calculation, which is absent from hydrodynamic simulation using other initialization methods, and it can be tested by future experimental data with higher precision. The relation between global polarization and the directed flow of A is explored as the longitudinal flow field or the medium deformation varies. Due to the common origin of these two observables, their combination may provide a more stringent constraint on the initial condition of the QGP.

关键词