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arXiv 0802.2598hep-ph
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带电粒子赝快度分布的中心性、系统尺寸和能量依赖性

Centrality, system size and energy dependences of charged-particle pseudo-rapidity distribution

De-ming Wei, Feng-lan Shao, Jun Song, Yun-fei Wang

摘要:

利用夸克组合模型中的三火球图像,系统地研究了Au+Au和Cu+Cu碰撞系统中带电粒子赝快度分布随碰撞中心度和能量($\sqrt{s_{NN}}=$ 19.6,62.4,130和200 GeV)的变化。我们发现:(i)领先粒子对$dN_{ch}/dη$分布的贡献分别随碰撞中心度和碰撞能量的减小而增大,(ii)领先粒子的数目几乎与碰撞能量无关,但与核子参与者$N_{part}$有关;(iii)如果在相同碰撞能量下的Cu+Cu和Au+Au碰撞被选择为具有相同的$N_{part}$,带电粒子$dN/dη$分布的结果在中快度粒子密度和分布宽度方面几乎相同。对于62.4 GeV和200 GeV的数据都是如此。㈣再现了有限的碎裂现象。(iiv)我们预测了$\sqrt{s_{NN}}= 5.5$ TeV的Pb+Pb碰撞中带电粒子的总多重数和赝快度分布。最后,我们对从RHIC到LHC的$N_{ch}/<N_{part}/2>$和$dN_{ch}/dη/<N_{part}/2>|_{η\approx0}$作为$\sqrt{s_{NN}}$和$N_{part}$的函数进行了定性分析。

英文摘要:

Utilizing the three-fireball picture within the quark combination model, we study systematically the charged particle pseudorapidity distributions in both Au+Au and Cu+Cu collision systems as a function of collision centrality and energy, $\sqrt{s_{NN}}=$ 19.6, 62.4, 130 and 200 GeV, in full pseudorapidity range. We find that: (i)the contribution from leading particles to $dN_{ch}/dη$ distributions increases with the decrease of the collision centrality and energy respectively; (ii)the number of the leading particles is almost independent of the collision energy, but it does depend on the nucleon participants $N_{part}$; (iii)if Cu+Cu and Au+Au collisions at the same collision energy are selected to have the same $N_{part}$, the resulting of charged particle $dN/dη$ distributions are nearly identical, both in the mid-rapidity particle density and the width of the distribution. This is true for both 62.4 GeV and 200 GeV data. (iv)the limiting fragmentation phenomenon is reproduced. (iiv) we predict the total multiplicity and pseudorapidity distribution for the charged particles in Pb+Pb collisions at $\sqrt{s_{NN}}= 5.5$ TeV. Finally, we give a qualitative analysis of the $N_{ch}/<N_{part}/2>$ and $dN_{ch}/dη/<N_{part}/2>|_{η\approx0}$ as function of $\sqrt{s_{NN}}$ and $N_{part}$ from RHIC to LHC.

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