Abstract
Global hyperon polarization, P¯H, in Au+Au collisions over a large range of collision energy, sNN, was recently measured and successfully reproduced by hydrodynamic and transport models with intense fluid vorticity of the quark-gluon plasma. While naïve extrapolation of data trends suggests a large P¯H as the collision energy is reduced, the behavior of P¯H at small sNN<7.7 GeV is unknown. Operating the STAR experiment in fixed-target mode, we measured the polarization of Λ hyperons along the direction of global angular momentum in Au+Au collisions at sNN=3 GeV. The observation of substantial polarization of 4.91±0.81(stat.)±0.15(syst.)% in these collisions may require a reexamination of the viscosity of any fluid created in the collision, of the thermalization timescale of rotational modes, and of hadronic mechanisms to produce global polarization.
Original language | English |
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Article number | L061901 |
Journal | Physical Review C |
Volume | 104 |
Issue number | 6 |
DOIs | |
State | Published - Dec 2021 |
Bibliographical note
Publisher Copyright:© 2021 American Physical Society.
ASJC Scopus subject areas
- Nuclear and High Energy Physics