"Table 311" 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.

CERN-LHC。重离子碰撞中喷注碎裂为带电粒子的相关研究，可为这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（jet-quenching）机制提供研究线索。本文借助大型强子对撞机（Large Hadron Collider, LHC）上的ATLAS探测器（ATLAS），测量了核子-核子质心系能量√s_NN=5.02太电子伏特（TeV）的铅-铅（Pb+Pb）与质子-质子（pp）碰撞中，喷注轴周围带电粒子的角分布。其中铅-铅与质子-质子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anti-kt算法（anti-kt algorithm）重建、半径参数R=0.4的喷注，并将分析范围拓展至距喷注轴角距离r=0.8的区域。针对横向动量处于1~63 GeV范围、与横向动量126~316 GeV且快度绝对值小于1.7的喷注匹配的带电粒子，结果以铅-铅碰撞中心度以及与喷注轴的角距离为变量进行展示。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效应进行量化分析。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-铅碰撞的喷注核心区域（与喷注轴角距离不超过r=0.05）产额得到增强，而在更大角距离处则出现产额压低现象。