在158 $A$~GeV中心Pb + Pb，Si + Si，C + C和非弹性p + p碰撞中$K^{\ast}(892)^0$和$\bar{K}^{\ast}(892)^0$的产生
$K^{\ast}(892)^0$ and $\bar{K}^{\ast}(892)^0$ production in central Pb+Pb, Si+Si, C+C and inelastic p+p collisions at 158$A$~GeV
摘要：
在CERN SPS上用NA49探测器研究了158 \agev（$\sqrt{s_{NN}}$ = 17.3 GeV）的中心Pb + Pb，Si + Si，C + C和非弹性p + p碰撞中$K^{\ast}(892)^0$和$\bar{K}^{\ast}(892)^0$共振的产生.测量了横向动量和快度分布，并估计了总产量。在核-核反应中，$K^{\ast}$的产率超过$\bar{K}^{\ast}$约两倍。总的产额比$< K^{\ast} >/< K^+ >$和$< \bar{K}^{\ast} >/< K^->$强烈抑制中心Pb + Pb相比，p + p，C + C和Si + Si的碰撞与预期的衰减这些短寿命的共振态的强子阶段的膨胀火球。UrQMD模型，虽然纳入了这样的场景，并没有提供一个定量的描述实验结果。统计强子气体模型假设相同的冻结参数稳定的强子和共振高估了$< K^{\ast} >/< K >$比率在中央铅+铅碰撞约2.5倍。
英文摘要：
Production of the $K^{\ast}(892)^0$ and $\bar{K}^{\ast}(892)^0$ 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 158\agev ($\sqrt{s_{NN}}$ = 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 $K^{\ast}$ exceeds that of $\bar{K}^{\ast}$ by about a factor of two in nucleus-nucleus reactions. The total yield ratios $< K^{\ast} >/< K^+ >$ and $< \bar{K}^{\ast} >/< K^->$ 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 $< K^{\ast} >/< K >$ ratios in central Pb+Pb collisions by about a factor of 2.5.
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