System-size and centrality dependence of charged kaon and pion production in nucleus-nucleus collisions at 40A GeV and158A GeV beam energy

TL;DR

This study investigates how the production of charged pions and kaons varies with system size and collision centrality in nucleus-nucleus collisions at 40A and 158A GeV, revealing a steep increase in strangeness production for small systems and saturation for larger ones.

Contribution

It provides detailed measurements of strangeness production dependence on system size and centrality at two energies, comparing results with various theoretical models.

Findings

Steep increase in strangeness production for small systems

Weak rise or saturation in larger systems

Comparison with transport and percolation models

Abstract

Measurements of charged pion and kaon production are presented in centrality selected Pb+Pb collisions at 40A GeV and 158A GeV beam energy as well as in semi-central C+C and Si+Si interactions at 40A GeV. Transverse mass spectra, rapidity spectra and total yields are determined as a function of centrality. The system-size and centrality dependence of relative strangeness production in nucleus-nucleus collisions at 40A GeV and 158A GeV beam energy are derived from the data presented here and published data for C+C and Si+Si collisions at 158A GeV beam energy. At both energies a steep increase with centrality is observed for small systems followed by a weak rise or even saturation for higher centralities. This behavior is compared to calculations using transport models (UrQMD and HSD), a percolation model and the core-corona approach.