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arXiv · 2312.11325

Directed flow and hyperon polarization at RHIC BES from multi-fluid dynamics

Iurii Karpenko·Jakub Cimerman
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Abstract

We present directed flow of protons and pions, as well as mean polarization of $\Lambda$ and $\bar\Lambda$ hyperons computed for Au-Au collisions at $\sqrt{s_\mathrm{NN}}=5...19.6$ GeV in MUFFIN model. MUlti Fluid simulation for Fast IoN collisions, or MUFFIN, is a state-of-the-art 3-fluid dynamic model for simulating heavy-ion collisions in the region from a few to a hundred GeV center-of-mass energy. Whereas MUFFIN succeeds to reproduce basic observables in the collision energy range of interest, the slope of the directed flow at mid-rapidity is much steeper as compared to the data, it has unclear EoS dependence and final-state hadronic cascade affects this observable significantly. The excitation function of the $\Lambda$ polarization shows a significant splitting between polarizations of $\Lambda$ and $\bar\Lambda$, which challenges a widespread interpretation that the splitting is affected mainly by the late-stage magnetic field.

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Iurii Karpenko, Jakub Cimerman. 2023-12-18. Directed flow and hyperon polarization at RHIC BES from multi-fluid dynamics. https://arxiv.org/abs/2312.11325

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