Speaker
Description
In hydrodynamic approach to heavy ion collisions, hadrons with nonzero spin produced out of the fluid can acquire polarization via spin-vorticity thermodynamic coupling mechanism [1]. The hydrodynamical quantity steering the polarization is the thermal vorticity, that is minus the antisymmetric part of the gradient of four-temperature field $\beta^\mu=u^\mu/T$.
Based on this idea, it has been shown in the framework of cascade+viscous hydro model, UrQMD+vHLLE [2] that in Au-Au collisions at RHIC Beam Energy Scan (BES) the mean polarization of Lambda hyperons grows with decreasing collision energy up to 1.5% at sqrt{s}=7.7 GeV RHIC Au-Au collisions. This goes in line with recent measurements of Lambda polarization by STAR experiment [3].
We complement the existing Lambda polarization studies at RHIC BES [1] by exploring:
- polarization splitting between Lambda and anti-Lambda, and related effect of magnetic field at hadronization,
- centrality dependence and connection between angular momentum of the system and polarization of produced Lambda,
- longitudinal component of polarization, which persists at high (full RHIC and LHC) energies.
[1] F. Becattini, V. Chandra, L. Del Zanna, E. Grossi, Ann. Phys. 338 (2013) 32.
[2] I. Karpenko, F. Becattini, Eur. Phys. J. C (2017) 77: 213
[3] STAR collaboration, arXiv:1701.06657
| List of tracks | Chiral magnetic effect and wave, chiral vortical effect |
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