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 √(s_NN)= 3.2 GeV are analyzed by employing a statistical model. Accounting for the identified hadrons π^0, η, Λ, K^0_s, ω allows a surprisingly good description of their abundances with parameters T_chem=(99±11) MeV and μ_b=(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 √(s_NN)= 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.