Münster 2002 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 27: Heavy Ions III

HK 27.3: Group Report

Wednesday, March 13, 2002, 11:45–12:15, E

Chemical Freeze-out of Antihyperons in Relativistic Heavy Ion Collisions — •Carsten Greiner — Institut fuer Theoretische Physik, Universitaet Giessen

We elaborate on our recent suggestion on antihyperon production in relativistic heavy ion collisions solely by means of multi-mesonic (fusion-type) reactions. It will be shown that the antihyperons are driven towards chemical equilibrium with pions, nucleons and kaons on a timescale of 1–3 fm/c in a still moderately baryon-dense hadronic environment. Explicit rate calculations for a dynamical setup will be presented and detail the proposed picture. For an estimated entropy to baryon ratio of S/A ≈ 30−40 at maximum SPS energies yields of each antihyperon specie are obtained which are consistent with chemical saturated populations of T ≈ 150−160 MeV. The proposed picture thus supports dynamically the chemical freeze-out for the antibaryons at such a temperature. The production process should also dominate at AGS energies or at energies of possible future heavy ion facilities at GSI.