Measurement of global polarization of Λ hyperons in few-GeV heavy-ion collisions

0567977 - ÚJF 2023 RIV NL eng J - Článek v odborném periodiku
Abou Yassine, R. - Adamczewski-Musch, J. - Asal, C. - Becker, M. - Chlad, Lukáš - Chudoba, Petr - Kugler, Andrej - Prozorov, Alexandr P. - Rodriguez Ramos, Pablo - Svoboda, Ondřej - Tlustý, Pavel - Wagner, Vladimír … celkem 108 autorů
Measurement of global polarization of Λ hyperons in few-GeV heavy-ion collisions.
Physics Letters. B. Roč. 835, DEC (2022), č. článku 137506. ISSN 0370-2693. E-ISSN 1873-2445
Grant CEP: GA MŠMT LTT17003; GA MŠMT EF18_046/0016066
Výzkumná infrastruktura: FAIR-CZ II - 90112
Institucionální podpora: RVO:61389005
Klíčová slova: heavy ion collision * HADES
Obor OECD: Nuclear physics
Impakt faktor: 4.3, rok: 2022
Způsob publikování: Open access
https://doi.org/10.1016/j.physletb.2022.137506

The global polarization of Λ hyperons along the total orbital angular momentum of a relativistic heavy-ion collision is presented based on the high statistics data samples collected in Au+Au collisions at sNN=2.4 GeV and Ag+Ag at 2.55 GeV with the High-Acceptance Di-Electron Spectrometer (HADES) at GSI, Darmstadt. This is the first measurement below the strangeness production threshold in nucleon-nucleon collisions. Results are reported as a function of the collision centrality as well as a function of the hyperon's transverse momentum (pT) and rapidity (yCM) for the range of centrality 0–40%. We observe a strong centrality dependence of the polarization with an increasing signal towards peripheral collisions. For mid-central (20 – 40%) collisions the polarization magnitudes are 〈PΛ〉(%)=6.8±1.3(stat.)±2.1(syst.) for Au+Au and 〈PΛ〉(%)=6.2±0.4(stat.)±0.6(syst.) for Ag+Ag, which are the largest values observed so far. This observation thus provides a continuation of the increasing trend previously observed by STAR and contrasts expectations from recent theoretical calculations predicting a maximum in the region of collision energies about 3 GeV. The observed polarization is of a similar magnitude as predicted by 3D-fluid-dynamics and the UrQMD plus thermal vorticity model and significantly above results from the AMPT model.
Trvalý link: https://hdl.handle.net/11104/0339287