"Table 209" 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.

欧洲核子研究中心大型强子对撞机（CERN-LHC）。针对重离子碰撞中喷注碎裂为带电粒子过程的研究，可为此类碰撞中产生的高温致密量子色动力学（Quantum Chromodynamics, QCD）物质——夸克-胶子等离子体（quark-gluon plasma）引发的喷注淬火机制提供相关信息。本文借助大型强子对撞机上的ATLAS探测器（ATLAS detector），对质心系能量√sNN=5.02 TeV的铅-铅（Pb+Pb）与质子-质子（pp）碰撞中，围绕喷注轴的带电粒子角分布开展了测量。其中铅-铅与质子-质子数据集的积分亮度分别为0.49 nb⁻¹与25 pb⁻¹。本次测量针对采用anti-kt算法（anti-kt algorithm）、半径参数R=0.4重建得到的喷注，并将分析范围拓展至距喷注轴角距离r=0.8处。结果以铅-铅碰撞中心度、带电粒子与喷注轴的角距离为变量呈现，所涉带电粒子的横向动量区间为1~63 GeV，其匹配的喷注横向动量区间为126~316 GeV，且喷注快度绝对值小于1.7。通过与质子-质子碰撞中的测量结果取比值，可对测得的分布的修正程度进行量化。观测发现，横向动量低于4 GeV的带电粒子产额随与喷注轴的角距离增大而持续提升，在r=0.6处达到峰值。横向动量高于4 GeV的带电粒子，在铅-铅碰撞中，与喷注轴角距离不超过r=0.05的喷注核心区域内产额有所提升，而在更大角距离处则受到抑制。