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arXiv 0903.0396hep-ph
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40 $A$和158 $A$ GeV(多奇异)超子的中心性和系统尺寸依赖性:二元碰撞和Boltzmann +流体动力学混合模型之间的比较

Centrality and system size dependence of (multi-strange) hyperons at 40$A$ and 158$A$ GeV: A comparison between a binary collision and a Boltzmann + hydrodynamic hybrid model

Hannah Petersen, Michael Mitrovski, Tim Schuster, Marcus Bleicher

摘要:

利用超相对论量子分子动力学(UrQMD-v2.3)模型和Boltzmann+流体动力学耦合计算,研究了40 $A$和158 $A$ GeV的Pb+Pb碰撞中(多奇异)超子的中心性和系统尺寸依赖性.第二种方法是实现在一个混合的方式的基础上UrQMD与中间流体动力学演化的热和密集的碰撞阶段。这种实施方式允许微观输运计算与流体动力学模拟的比较,以探索从不完全平衡的系统(例如C+C或Si+Si碰撞)到假定完全平衡的系统(例如在Pb+Pb反应中产生的系统)的过渡。计算结果与NA 49和NA 57合作组在40 $A$和158 $A$ GeV的中快度($\mid$ y $\mid$ $\leq$ 0.5)和总多重数的测量结果进行了比较。此外,我们比较了我们的预测$Λ$,$\barΛ$和$Ξ^{-}$快度谱和总多重性的中心依赖在40 $A$和158 $A$ GeV,在可能的情况下。

英文摘要:

We present results on the centrality and system size dependence of (multi-strange)hyperons in Pb+Pb collisions at 40$A$ and 158$A$ GeV from the Ultra-relativistic Quantum Molecular Dynamics (UrQMD-v2.3) model and a coupled Boltzmann+hydrodynamics calculation. The second approach is realized in a hybrid fashion based on UrQMD with an intermediate hydrodynamical evolution for the hot and dense stage of the collision. This implementation allows a comparison of microscopic transport calculations with hydrodynamic simulations to explore the transition from a system that is not fully equilibrated such as C+C or Si+Si collisions, to a supposedly fully equilibrated system, such as that created in Pb+Pb reactions. The results of our calculation are compared to measurements of the (anti-)hyperon yields at midrapidity ($\mid$y$\mid$ $\leq$ 0.5) and total multiplicities performed by the NA49 and NA57 Collaborations at 40$A$ and 158$A$ GeV. Furthermore, we compared our predictions to the centrality dependence of $Λ$, $\barΛ$ and $Ξ^{-}$ rapidity spectra and total multiplicities at 40$A$ and 158$A$ GeV, where possible.

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