K^*(892)0 and K^*(892)0 production in central Pb + Pb, Si + Si, C + C, and inelastic p + p collisions at 158A GeV

Production of the K^*(892⁾0 and K^*(892⁾0 resonances was studied via their K⁺π^- and K^-π⁺ decay modes in central Pb+Pb, Si+Si, C+C, and inelastic p+p collisions at 158A GeV(√s_NN=17.3 GeV) with the NA49 detector at the CERN SPS. Transverse momentum and rapidity distributions were measured and total yields were estimated. The yield of K^* exceeds that of K ^* by about a factor of two in nucleus-nucleus reactions. The total yield ratios K^*/⁺ and ^* / ^- are strongly suppressed in central Pb+Pb compared to p+p, C+C, and Si+Si collisions, in agreement with the expected attenuation of these short-lived resonance states in the hadronic phase of the expanding fireball. The UrQMD model, although incorporating such a scenario, does not provide a quantitative description of the experimental results. The statistical hadron gas model assuming the same freeze-out parameters for stable hadrons and resonances overestimates the ^* / ratios in central Pb+Pb collisions by about a factor of 2.5.