"Table 331" 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）的相关研究表明，重离子碰撞中喷注碎裂为带电粒子的过程分析，可为该类碰撞产生的热密量子色动力学（Quantum Chromodynamics, QCD）物质——夸克-胶子等离子体（quark-gluon plasma）所引发的喷注淬火机制提供关键信息。本文利用大型强子对撞机（LHC）上的ATLAS探测器，报道了质心系核子-核子碰撞能量√s_NN=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的测量结果。其中Pb+Pb与pp数据集的积分亮度分别为0.49纳靶恩⁻¹（nb⁻¹）与25皮靶恩⁻¹（pb⁻¹）。本次测量针对采用反k_t（anti-kt）算法、半径参数R=0.4重建的喷注展开，并将分析范围拓展至距喷注轴角距离r=0.8的区域。分析对象为横向动量介于1~63 GeV区间的带电粒子，这些粒子与横向动量介于126~316 GeV、喷注快度绝对值小于1.7的喷注匹配；结果以Pb+Pb碰撞中心度及与喷注轴的角距离为变量呈现。通过与pp碰撞的测量结果取比值，可量化评估测得的粒子分布所受的修正效应。观测结果显示：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；而横向动量高于4 GeV的带电粒子，在与喷注轴角距离不超过r=0.05的喷注核心区域内，Pb+Pb碰撞中的产额有所提升，但在更大角距离处则表现为产额被抑制。