Strange baryonic resonances and resonances coupling to strange hadrons at SIS energies

Abstract

The role played by baryonic resonances in the production of final states containing strangeness for proton-proton reactions at 3.5 GeV measured by HADES is discussed by means of several very different measurements. First the associate production of $\Delta$ resonances accompanying final states with strange hadrons is presented, then the role of interferences among N$^*$ resonances, as measured by HADES for the first time, is summarised. Last but not least the role played by heavy resonances, with a mass larger than $2$ GeV/c$^2$ in the production of strange and non-strange hadrons is discussed. Experimental evidence for the presence of a $\Delta(2000)^{++}$ are presented and hypotheses are discussed employing the contribution of similar objects to populate the excesses measured by HADES for the $\Xi$ in A+A and p+A collisions and in the dilepton sector for A+A collisions. This extensive set of results helps to better understand the dynamic underlaying particle production in elementary reactions and sets a more solid basis for the understanding of heavy ion collisions at the same energies and even higher as planned at the FAIR facility.