System-size dependence of particle-ratio fluctuations in Pb + Pb collisions at 158A GeV

Abstract

New measurements by the NA49 experiment of the centrality dependence of event-by-event fluctuations of the particle yield ratios (K[superscript +]+K[superscript -])/(π[superscript +]+π[superscript -]), (p+p̅ )/(π[superscript +]+π[superscript -]), and (K[superscript +]+K[superscript -])/(p+p̅ ) are presented for Pb+Pb collisions at 158A GeV. The absolute values of the dynamical fluctuations of these ratios, quantified by the measure σdyn, increase by about a factor of two from central to semiperipheral collisions. Multiplicity scaling scenarios are tested and found to apply for both the centrality and the previously published energy dependence of the (K[superscript +]+K[superscript -])/(π[superscript +]+π[superscript -]) and (p+p̅ )/(π[superscript +]+π[superscript -]) ratio fluctuations. A description of the centrality and energy dependence of (K[superscript +]+K[superscript -])/(p+p̅ ) ratio fluctuations by a common scaling prescription is not possible since there is a sign change in the energy dependence.