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Article
Report number arXiv:2107.11183 ; CERN-EP-2021-148
Title Polarization of Λ and ¯Λ hyperons along the beam direction in Pb–Pb collisions at sNN = 5.02 TeV
Author(s) Acharya, Shreyasi (Calcutta, VECC) ; Adamova, Dagmar (Rez, Nucl. Phys. Inst.) ; Adler, Alexander (Goethe U., Frankfurt, Inst. Inform.) ; Aglieri Rinella, Gianluca (CERN) ; Agnello, Michelangelo (Turin Polytechnic) ; Agrawal, Neelima (INFN, Bologna) ; Ahammed, Zubayer (Calcutta, VECC) ; Ahmad, Shakeel (Aligarh Muslim U.) ; Ahn, Sang Un (KISTI, Daejeon) ; Ahuja, Ishaan (Kosice U.) 1037 人のオーサーを表示
Corporate author(s) The ALICE collaboration
Publication 2022-04-29
Imprint 21 Jul 2021
Number of pages 18
Note 18 pages, 4 captioned figures, authors from page 12, published version, figures at http://alice-publications.web.cern.ch/node/7262
Published in: Phys. Rev. Lett. 128 (2022) 172005
DOI 10.1103/PhysRevLett.128.172005
Subject category Nuclear Physics - Experiment
Accelerator/Facility, Experiment CERN LHC ; ALICE
Keywords relativistic heavy ion physics ; quark gluon plasma ; polarization ; particle correlations and fluctuations ; experimental results
Abstract The polarization of the Λ and ¯Λ hyperons along the beam (z) direction, Pz, has been measured in Pb–Pb collisions at sNN = 5.02 TeV recorded with ALICE at the Large Hadron Collider (LHC). The largest contribution to Pz comes from elliptic flow induced vorticity and can be characterized by the second Fourier sine coefficient Pz,s2 = Pzsin(2φ2Ψ2), where φ is the hyperon azimuthal emission angle, and Ψ2 is the elliptic flow plane angle. We report the measurement of Pz,s2 for different collision centralities, and in the 30–50% centrality interval as a function of the hyperon transverse momentum and rapidity. The Pz,s2 is positive similarly as measured by the STAR Collaboration in Au–Au collisions at sNN = 200 GeV, with somewhat smaller amplitude in the semi-central collisions. This is the first experimental evidence of a non-zero hyperon Pz in Pb–Pb collisions at the LHC. The comparison of the measured Pz,s2 with the hydrodynamic model calculations shows sensitivity to the competing contributions from thermal and the recently found shear induced vorticity, as well as to whether the polarization is acquired at the quark-gluon plasma or the hadronic phase.
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Copyright/License publication: (License: CC-BY-4.0)
Preprint: © 2021-2025 CERN (License: CC-BY-4.0)
Submitted by yvonne.chiara.pachmayer@cern.ch



 


 レコード 生成: 2021-07-21, 最終変更: 2025-01-06


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