"Table 292" 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）。重离子碰撞中喷注碎裂为带电粒子的研究，可为这类碰撞中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（jet-quenching）机制提供相关信息。本文针对质心系能量√s_NN=5.02 TeV的铅-铅（Pb+Pb）与质子-质子（pp）碰撞，利用ATLAS探测器（ATLAS detector）测量了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 nb⁻¹与25 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的喷注开展，并将分析范围拓展至距喷注轴角距离r=0.8的区域。研究结果以铅-铅碰撞中心度与带电粒子距喷注轴的角距离为变量进行呈现，所涉带电粒子的横向动量范围为1~63 GeV，对应的匹配喷注横向动量范围为126~316 GeV，且喷注快度绝对值小于1.7。通过与质子-质子碰撞的测量结果取比值，可对观测分布的修正效应进行量化表征。研究发现，横向动量低于4 GeV的带电粒子产额随距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，在铅-铅碰撞的喷注核心区域（距喷注轴角距离不超过r=0.05）产额有所提升，但在更大角距离处则呈现抑制效应。