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HK: Fachverband Physik der Hadronen und Kerne
HK 24: Heavy-Ion Collisions and QCD Phases IV
HK 24.4: Talk
Wednesday, March 18, 2026, 14:45–15:00, PHIL A 401
Global Lambda Polarization in Au+Au collisions at 0.8 AGeV measured with HADES — •Florian Alef for the HADES collaboration — TU Darmstadt, Darmstadt, Germany
In heavy-ion collisions, large angular momenta are generated which might translate to a spin polarization of the produced particles.
Extracting the spin orientation of an outgoing proton from a weakly decaying Λ hyperon with respect to the reaction plane could probe a global polarization and be a hint for high vorticities in the early stages of the collision.
Measurements of the Λ polarization by HADES and STAR collaboration both indicate a strong enhancement towards lower beam energies, reaching ⟨ PΛ⟩(%)=4.4±0.3 (stat.)±0.4 (sys.) in Ag+Ag collisions at √sNN=2.55 GeV, which corresponds to the free NN Λ production threshold.
This contribution will report on the status of the Λ polarization in Au+Au collisions at √sNN=2.25 GeV measured with HADES, which is the first Λ polarization measurement below the production threshold.
Keywords: Lambda; Polarization; HADES; Event plane; Vorticity