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 a center-of-mass energy of root s(NN) = 3.2 GeV are analyzed employing a statistical hadronization model. The model can successfully describe the production yields of the identified hadrons pi(0), eta, Lambda, K-s(0), omega with parameters T-chem = (99 +/- 11) MeV and mu(b) = (619 +/- 34) MeV, which fit well into the chemical freeze-out systematics found in heavy-ion collisions. In addition, we reanalyze our previous HADES data from Ar + KCl collisions at root s(NN) = 2.6 GeV with an updated version of the 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 as a function of colliding energy and system size. Despite its success, the model fails to describe the observed Xi(-) yields in both, p + Nb and Ar + KCl. Special emphasis is put on feed-down contributions from higher-lying resonance states as a possible explanation for the observed excess.