标题： 带电强子在氙-氙碰撞中的赝快度分布，能量为$\sqrt{s_\mathrm{NN}} =$ 5.44 TeV 显示英文标题

标题： Pseudorapidity distributions of charged hadrons in xenon-xenon collisions at $\sqrt{s_\mathrm{NN}} =$ 5.44 TeV

摘要： 赝快度分布的测量结果在质子-质子对心碰撞能量为$\sqrt{s_\mathrm{NN}} =$5.44 TeV 的氙-氙碰撞中被呈现。 这些测量基于CMS实验在大型强子对撞机上收集的数据。 利用CMS追踪系统中的硅像素探测器，在赝快度范围$|\eta|$$<$3.2 内确定了在氙-氙碰撞中产生的原始带电强子的产率。 对于最中央的5%的碰撞，在中间快速度区域$|\eta|$ $<$ 0.5 发现带电强子的赝快度密度为1187 $\pm$36（系统），统计不确定性可以忽略不计。 带电强子的快度分布也在范围$|y|$ $<$ 3.2 内给出，并发现其在快度$y =$ 0 附近与快度无关。 现有的蒙特卡罗事件生成器无法同时描述这两个结果。 在相似碰撞能量下，氙-氙和铅-铅碰撞中带电强子多重性的比较显示，除了系统大小和碰撞能量外，中间快度处的粒子产生强烈依赖于碰撞几何结构。 显示英文摘要

摘要： Measurements of the pseudorapidity distributions of charged hadrons produced in xenon-xenon collisions at a nucleon-nucleon centre-of-mass energy of $\sqrt{s_\mathrm{NN}} =$ 5.44 TeV are presented. The measurements are based on data collected by the CMS experiment at the LHC. The yield of primary charged hadrons produced in xenon-xenon collisions in the pseudorapidity range $|\eta|$ $<$ 3.2 is determined using the silicon pixel detector in the CMS tracking system. For the 5% most central collisions, the charged-hadron pseudorapidity density in the midrapidity region $|\eta|$ $<$ 0.5 is found to be 1187 $\pm$ 36 (syst), with a negligible statistical uncertainty. The rapidity distribution of charged hadrons is also presented in the range $|y|$ $<$ 3.2 and is found to be independent of rapidity around $y =$ 0. Existing Monte-Carlo event generators are unable to simultaneously describe both results. Comparisons of charged-hadron multiplicities between xenon-xenon and lead-lead collisions at similar collision energies show that particle production at midrapidity is strongly dependent on the collision geometry in addition to the system size and collision energy.