SMuK 2021 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 17: Heavy-Ion Collisions and QCD Phases III
HK 17.1: Group Report
Wednesday, September 1, 2021, 16:30–17:00, H1
Global polarization of Λ hyperons as a probe for vortical effects in A+A collisions with HADES — •Frederic Kornas1, Ilya Selyuzhenkov2, and Tetyana Galatyuk1,2 for the HADES collaboration — 1TU Darmstadt, Darmstadt, Germany — 2GSI Helmholtzzentrum, Darmstadt, Germany
Large orbital momenta occur in non-central heavy-ion collisions which might transfer to the particle spins resulting in a global polarization of the produced particles. Such a global polarization can be measured using weakly decaying particles, e.g. the Λ hyperon. The results of the Λ polarization measurement in Au+Au collisions at √sNN = 2.4 GeV and Ag+Ag collisions at √sNN = 2.55 GeV will be reported. For the latter, the polarization will be shown as a function of centrality, rapidity and transverse momentum. The magnitude of the measured polarization by HADES follows the increasing trend with decreasing collision energy observed by the STAR and ALICE collaborations at higher energies. In addition, directed flow v1 measurements of the Λ will be shown. The v1 slope at midrapidity will be compared to the protons measured in the same collision systems in HADES and put in the context of previous measurement.