Hyperon global polarization in isobar Ru+Ru and Zr+Zr collisions at √sNN=200GeV
The polarization of Λ, Λ̄ , Ξ−, and Ξ̄ + hyperons along the angular momentum of the system has been measured in isobar collisions of Ru+Ru and Zr+Zr at √𝑠NN = 200 GeV with the STAR detector at RHIC. The polarization dependence on collision centrality exhibits an increasing trend in more peripheral c...
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| Main Authors: | , , , |
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| Corporate Author: | |
| Format: | Article (Journal) Editorial |
| Language: | English |
| Published: |
November 2025
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| In: |
Physics letters
Year: 2025, Volume: 870, Pages: 1-9 |
| ISSN: | 1873-2445 |
| DOI: | 10.1016/j.physletb.2025.139891 |
| Online Access: | Verlag, kostenfrei, Volltext: https://doi.org/10.1016/j.physletb.2025.139891 Verlag, kostenfrei, Volltext: https://www.sciencedirect.com/science/article/pii/S0370269325006501 
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| Author Notes: | The STAR Collaboration* |
| Summary: | The polarization of Λ, Λ̄ , Ξ−, and Ξ̄ + hyperons along the angular momentum of the system has been measured in isobar collisions of Ru+Ru and Zr+Zr at √𝑠NN = 200 GeV with the STAR detector at RHIC. The polarization dependence on collision centrality exhibits an increasing trend in more peripheral collisions. Λ and Λ̄ polarization dependence on the transverse momentum and pseudorapidity have been investigated, but no significant dependence was observed. The polarizations of Λ and Λ̄ are found to be consistent with each other, indicating little contribution of the spin-magnetic coupling to the measured polarization. Comparison to previously measured polarization in Au+Au collisions show no obvious system size dependence. The results are qualitatively consistent with hydrodynamic calculations including contributions from shear-induced polarization and thermal vorticity. For the first time in heavy-ion collisions, the dependence of the global polarization on the hyperon’s emission azimuthal angle relative to the second-order event plane has been measured, indicating stronger polarization for the in-plane emitted hyperons at the level of 2.4𝜎 significance in 20–50% centrality. The Ξ hyperon polarization measurements via polarization transfer analysis yield finite positive values with 2.9𝜎 significance in 20–50% centrality, slightly larger compared to the inclusive Λ polarization. |
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| Item Description: | Online verfügbar: 1. Oktober 2025, Artikelversion: 5. November 2025 *The STAR Collaboration: B.E. Aboona, I.M. Deppner, Y.H. Leung, Y. Söhngen [und sehr viele weitere Personen] Gesehen am 17.03.2026 Im Titel steht der Ausdruck "sNN" unter dem Wurzelsymbol |
| Physical Description: | Online Resource |
| ISSN: | 1873-2445 |
| DOI: | 10.1016/j.physletb.2025.139891 |