Jun 12 – 16, 2017
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Europe/Zurich timezone

Study of Lambda polarization at RHIC BES energies and beyond

Jun 14, 2017, 9:25 AM
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Nikhef Science Park 105 1098XG Amsterdam The Netherlands


Dr Iurii Karpenko (INFN Firenze)


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

Primary authors

Dr Iurii Karpenko (INFN Firenze) Francesco Becattini (Unversity of Florence)

Presentation materials