System-size and centrality dependence of charged kaon and pion production in nucleus-nucleus collisions at 40<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>A</mml:mi></mml:math>GeV and 158<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>A</mml:mi></mml:math>GeV beam energy

Abstract

Measurements of charged pion and kaon production are presented in centrality selected $\mathrm{Pb}+\mathrm{Pb}$ collisions at 40$A$ GeV and 158$A$ GeV beam energy as well as in semicentral $\mathrm{C}+\mathrm{C}$ and $\mathrm{Si}+\mathrm{Si}$ interactions at 40$A$ 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 40$A$ GeV and 158$A$ GeV beam energy are derived from the data presented here and from published data for $\mathrm{C}+\mathrm{C}$ and $\mathrm{Si}+\mathrm{Si}$ collisions at 158$A$ 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 (ultra-relativistic quantum molecular dynamics and hadron-string dynamics), a percolation model, and the core-corona approach.