Global polarization of Λ and ‾Λ hyperons in Au+Au collisions at √sNN=19.6 and 27 GeV
- In relativistic heavy-ion collisions, a global spin polarization, PH, of Λ and Λ¯ hyperons along the direction of the system angular momentum was discovered and measured across a broad range of collision energies and demonstrated a trend of increasing PH with decreasing sNN−−−√. A splitting between Λ and Λ¯ polarization may be possible due to their different magnetic moments in a late-stage magnetic field sustained by the quark-gluon plasma which is formed in the collision. The results presented in this study find no significant splitting at the collision energies of sNN−−−√=19.6 and 27 GeV in the RHIC Beam Energy Scan Phase II using the STAR detector, with an upper limit of PΛ¯−PΛ<0.24% and PΛ¯−PΛ<0.35%, respectively, at a 95% confidence level. We derive an upper limit on the naïve extraction of the late-stage magnetic field of B<9.4⋅1012 T and B<1.4⋅1013 T at sNN−−−√=19.6 and 27 GeV, respectively, although more thorough derivations are needed. Differential measurements of PH were performed with respect to collision centrality, transverse momentum, and rapidity. With our current acceptance of |y|<1 and uncertainties, we observe no dependence on transverse momentum and rapidity in this analysis. These results challenge multiple existing model calculations following a variety of different assumptions which have each predicted a strong dependence on rapidity in this collision-energy range.
URN: | urn:nbn:de:hebis:30:3-849023 |
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URL: | https://arxiv.org/abs/2305.08705v1 |
DOI: | https://doi.org/10.48550/ARXIV.2305.08705 |
ArXiv Id: | http://arxiv.org/abs/2305.08705v1 |
Parent Title (English): | arXiv |
Publisher: | arXiv |
Document Type: | Preprint |
Language: | English |
Date of Publication (online): | 2023/03/15 |
Date of first Publication: | 2023/03/15 |
Publishing Institution: | Universitätsbibliothek Johann Christian Senckenberg |
Creating Corporation: | STAR Collaboration |
Release Date: | 2024/07/08 |
Issue: | 2305.08705v1 |
Edition: | Version 1 |
Page Number: | 8 |
Institutes: | Wissenschaftliche Zentren und koordinierte Programme / Frankfurt Institute for Advanced Studies (FIAS) |
Dewey Decimal Classification: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
Sammlungen: | Universitätspublikationen |
Licence (German): | Creative Commons - CC BY-NC-ND - Namensnennung - Nicht kommerziell - Keine Bearbeitungen 4.0 International |