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arXiv 0709.3030nucl-ex
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CERN SPS能核-核碰撞中(反)核和(反)超子产生的最新结果

Recent results on (anti)nucleus and (anti)hyperon production in nucleus-nucleus collisions at CERN SPS energies

G. L. Melkumov

摘要:

NA 49实验收集了关于在整个SPS束能量范围内核-核碰撞中粒子产生的全面数据,这是预计将发生预期的向去精细相的相变的临界能量域。本文介绍了20 $A$和158 $A$ GeV的Pb+Pb碰撞对重子停止、轻核产生和奇异超子产生的最新结果。利用$p$,$\bar{p}$,$Λ$,$\barΛ$,$Ξ^-$和$\barΞ^+$产生的测量数据,计算了SPS能区净重子的快度分布,并与AGS和RHIC的Pb+Pb(Au+Au)中心碰撞结果进行了比较.聚结和统计方法内的$m_t$谱的产额比和反斜率参数的碰撞能量和中心性,以及产生的核$^3He$,$t$,$d$和$\bar{d}$的质量数的依赖关系进行了讨论。总多重性的分析显示出显着的协议之间的测量产额为$^3He$和统计强子化模型预测。此外,还介绍了在40 $A$和158 $A$ GeV最小偏压Pb+Pb反应中,以及中心C+C,Si+Si和Pb+Pb碰撞中,$Λ$和$\barΛ$以及$Ξ^-$产生的新结果.分析了这些超子产额与系统尺寸的关系,以确定奇异增强相对于基本p+p碰撞的演化。

英文摘要:

The NA49 experiment has collected comprehensive data on particle production in nucleus-nucleus collisions over the whole SPS beam energies range, the critical energy domain where the expected phase transition to a deconfined phase is expected to occur. The latest results from Pb+Pb collisions between 20$A$ GeV and 158$A$ GeV on baryon stopping and light nuclei production as well as those for strange hyperons are presented. The measured data on $p$, $\bar{p}$, $Λ$, $\barΛ$, $Ξ^-$ and $\barΞ^+$ production were used to evaluate the rapidity distributions of net-baryons at SPS energies and to compare with the results from the AGS and the RHIC for central Pb+Pb (Au+Au) collisions. The dependence of the yield ratios and the inverse slope parameter of the $m_t$ spectra on the collision energy and centrality, and the mass number of the produced nuclei $^3He$, $t$, $d$ and $\bar{d}$ are discussed within coalescence and statistical approaches. Analysis of the total multiplicity exhibits remarkable agreement between the measured yield for $^3He$ and those predicted by the statistical hadronization model. In addition, new results on $Λ$ and $\barΛ$ as well as $Ξ^-$ production in minimum bias Pb+Pb reactions at 40$A$ GeV and 158$A$ GeV and central C+C, Si+Si and Pb+Pb collisions are presented. The system size dependence of the yields of these hyperons was analysed to determine the evolution of strangeness enhancement relative to elementary p+p collisions.

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