Statistical model analysis of hadron yields in proton-nucleus and heavy-ion collisions at SIS 18 energies

The HADES data from p+Nb collisions at center of mass energy of √ sNN= 3.2 GeV are analyzed by employing a statistical model. Accounting for the identified hadrons π, η, Λ, K s , ω allows a surprisingly good description of their abundances with parameters Tchem = (99 ± 11) MeV and μb = (619 ± 34) MeV, which fits well in the chemical freeze-out systematics found in heavy-ion collisions. In supplement we reanalyze our previous HADES data from Ar+KCl collisions at √ sNN= 2.6 GeV with an updated version of the statistical model. We address equilibration in heavy-ion collisions by testing two aspects: the description of yields and the regularity of freeze-out parameters from a statistical model fit. Special emphasis is put on feed-down contributions from higher-lying resonance states which have been proposed to explain the experimentally observed Ξ− excess present in both data samples. PACS. 25.75.-q, 25.75.Dw ar X iv :1 51 2. 07 07 0v 1 [ nu cl -e x] 2 2 D ec 2 01 5 2 The HADES collaboration (G. Agakishiev et al.): Statistical model analysis of hadron multiplicities at SIS 18 energy