"Table 355" of "Measurement of angular and momentum distributions of charged particles within and around jets in Pb+Pb and $pp$ collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV with the ATLAS detector"

CERN-LHC. Studies of the fragmentation of jets into charged particles in heavy-ion collisions can provide information about the mechanism of jet-quenching by the hot and dense QCD matter created in such collisions, the quark-gluon plasma. This paper presents a measurement of the angular distribution of charged particles around the jet axis in sNN=5.02 TeV Pb+Pb and pp collisions, using the ATLAS detector at the LHC. The Pb+Pb and pp data sets have integrated luminosities of 0.49 nb−1 and 25 pb−1, respectively. The measurement is performed for jets reconstructed with the anti-kt algorithm with radius parameter R=0.4 and is extended to an angular distance of r=0.8 from the jet axis. Results are presented as a function of Pb+Pb collision centrality and distance from the jet axis for charged particles with transverse momenta in the 1−63 GeV range, matched to jets with transverse momenta in the 126−316 GeV range and an absolute value of jet rapidity of less than 1.7. Modifications to the measured distributions are quantified by taking a ratio to the measurements in pp collisions. Yields of charged particles with transverse momenta below 4 GeV are observed to be increasingly enhanced as a function of angular distance from the jet axis, reaching a maximum at r=0.6. Charged particles with transverse momenta above 4 GeV have an enhanced yield in Pb+Pb collisions in the jet core for angular distances up to r=0.05 from the jet axis, with a suppression at larger distances.本文针对欧洲核子研究中心大型强子对撞机（CERN-LHC）的重离子碰撞实验展开分析：对重离子碰撞（heavy-ion collisions）中喷注碎裂为带电粒子过程的研究，可揭示此类碰撞中产生的高温致密量子色动力学（QCD）物质引发喷注淬火（jet-quenching）的物理机制，该物质即为夸克-胶子等离子体（quark-gluon plasma）。本文利用LHC上的ATLAS探测器（ATLAS detector），对质心系能量√s_NN=5.02太电子伏特（TeV）的铅-铅（Pb+Pb）与质子-质子（pp）碰撞中，喷注轴（jet axis）周围带电粒子的角分布（angular distribution）进行了测量。本次实验所用的Pb+Pb与pp碰撞数据集的积分亮度（integrated luminosities）分别为0.49纳靶恩的倒数（nb⁻¹）与25皮靶恩的倒数（pb⁻¹）。本次测量针对通过anti-kt聚类算法（anti-kt algorithm）重建的喷注完成，其中半径参数R=0.4，分析范围延伸至距喷注轴角距离r=0.8的区域。测量结果针对横向动量（transverse momenta）介于1~63 GeV的带电粒子展开，以Pb+Pb碰撞中心度（collision centrality）、距喷注轴的距离以及与喷注的匹配关系为变量；其中所匹配喷注的横向动量介于126~316 GeV，且喷注快度（jet rapidity）的绝对值小于1.7。通过与pp碰撞中的测量结果取比值，可量化分析Pb+Pb碰撞中带电粒子分布的修正效应。实验观测到，横向动量低于4 GeV的带电粒子产额（yields）随距喷注轴的角距离增大而持续提升，并在r=0.6处达到峰值。横向动量高于4 GeV的带电粒子则表现出：在Pb+Pb碰撞的喷注核心（jet core）区域（距喷注轴角距离不超过r=0.05时）产额有所提升，而在更大角距离处产额受到抑制（suppression）。