Global Polarization of and Hyperons in Collisions at
Global polarization of Ξ and Ω hyperons has been measured for the first time in Au+Au collisions at $$\sqrt{s_{NN}}$$=200 GeV. The measurements of the $$Ξ^{-}$$ and $$\overline{Ξ}^{+}$$ hyperon polarization have been performed by two independent methods, via analysis of the angular distribution of the daughter particles in the parity violating weak decay Ξ→Λ+π, as well as by measuring the polarization of the daughter Λ hyperon, polarized via polarization transfer from its parent. The polarization, obtained by combining the results from the two methods and averaged over $$Ξ^{-}$$ and $$\overline{Ξ}^{+}$$, is measured to be $$\langle{P_{Ξ}}\rangle$$=0.47±0.10(stat)±0.23(syst)% for the collision centrality 20%-80%. The $$\langle{P_{Ξ}}\rangle$$ is found to be slightly larger than the inclusive Λ polarization and in reasonable agreement with a multiphase transport model. The $$\langle{P_{Ξ}}\rangle$$ is found to follow the centrality dependence of the vorticity predicted in the model, increasing toward more peripheral collisions. Finally, the global polarization of Ω, $$\langle{P_{Ω}}\rangle$$=1.11±0.87(stat)±1.97(syst)% was obtained by measuring the polarization of daughter Λ in the decay Ω→Λ+K, assuming the polarization transfer factor $$C_{ΩΛ}=1$$.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States); Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP)
- Contributing Organization:
- STAR Collaboration
- Grant/Contract Number:
- AC02-05CH11231; SC0012704
- OSTI ID:
- 1807490
- Alternate ID(s):
- OSTI ID: 1755150
- Report Number(s):
- BNL-220759-2021-JAAM; BNL-220759-2020-JAAM; ark:/13030/qt1ht405zj; TRN: US2212789
- Journal Information:
- Physical Review Letters, Vol. 126, Issue 16; ISSN 0031-9007
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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