高能核碰撞中带电多重数快度与能量和中心度的关系

Energy and Centrality Dependences of Charged Multiplicity Pseudorapidity Density in Relativistic Nuclear Collisions

用强子 -弦级联模型JPCIAE及相应的MonteCarlo事例产生器研究相对论性核 -核碰撞中带电粒子多重数的赝快度密度对能量和中心度的依赖关系 .无需另调任何模型参数的条件下 ,此模型可以同时较好地描述相对论性pp实验数据及PHOBOS和PHENIX实验组的Au +Au实验数据 .本文指出 :因〈Npart〉并非严格定义的物理量 ,致使实验上和理论上确定〈Npart〉有一定任意性 ,从而使得每参加者核子对的带电粒子赝快度密度随着〈Npart〉的增加可能逐渐增大 ,也可能逐渐减小 。

Using a hadron and string cascade model, JPCIAE, and the corresponding Monte Carlo events generator, the energy and centrality dependences of charged particle pseudorapidity density in relativistic nuclear collisions were studied. Within the framework of this model, both the relativistic p p experimental data and the PHOBOS and PHENIX Au+Au data could be reproduced fairly well without retuning the model parameters. This paper shows that since < N part > is not a well defined physical variable both experimentally and theoretically, the charged particle pseudorapidity density per participant pair can increase and also can decrease with increasing of < N part >, so it may be hard to use charged particle pseudorapidity density per participant pair as a function of < N part > to distinguish various theoretical models for particle production.