Origin of subthresholdK+production in heavy ion collisions

Abstract

We investigate the origin of subthreshold K ϩ production in heavy ion collisions at intermediate energies. In particular we study the influence of the pion induced K ϩ creation processes. We find that this channel shows a strong dependence on the size of the system, i.e., the number of participating nucleons as well as on the incident energy of the reaction. In an energy region between 1 and 2 GeV/nucleon the pion induced processes essentially contribute to the total yield and can even become dominant in reactions with a large number of participating nucleons. Thus we are able to reproduce recent measurements of the KaoS Collaboration for 1 GeV/nucleon Au on Au reactions adopting a realistic momentum dependent nuclear mean field.

Kaon production in heavy ion reactions at intermediate energies

“…In [176] the frozen ∆ approximation has been used which includes pionic degrees of freedom implicitly. The importance of this channel was first pointed out by Fuchs et al [109]. These additional channels which contribute up to 30 ÷ 50% to the total yield allowed to explain the measured yields with realistic momentum dependent interactions [109,94].…”

“…The importance of this channel was first pointed out by Fuchs et al [109]. These additional channels which contribute up to 30 ÷ 50% to the total yield allowed to explain the measured yields with realistic momentum dependent interactions [109,94]. However, the dependence of the total K + yield on the nuclear EOS turned now out to be much smaller than originally expected, i.e.…”

Evidence for a Soft Nuclear Equation-of-State from Kaon Production in Heavy-Ion Collisions

“…At subthreshold beam energies, the production of kaons requires multiple nucleon-nucleon collisions or secondary collisions such as πN→K + Λ. These processes are expected to occur predominantly at high baryon densities, and the densities reached in the fireball depend on the nuclear equation-of-state [8].…”

Probing dense matter with strangeness production in nuclear collisions

“…At subthreshold beam energies, the production of kaons requires multiple nucleon-nucleon collisions or secondary collisions such as πN → K + Λ. These processes are expected to occur predominantly at high baryon densities, and the densities reached in the fireball depend on the nuclear equation-of-state [21]. According to transport calculations, in central Au + Au collisions the bulk of K + mesons is produced at nuclear matter densities larger than twice saturation density.…”