"Table 162" 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的过程开展研究，可揭示此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）引发喷注淬火（jet-quenching）的物理机制。

本文依托大型强子对撞机（LHC）上的ATLAS探测器（ATLAS），报道了√sNN=5.02 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测量结果。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）。

本次测量针对采用反k_t（anti-k_t）算法重建、半径参数R=0.4的喷注，并将分析拓展至距喷注轴角距离r=0.8的范围。测量结果以铅-铅碰撞中心度、带电粒子距喷注轴的角距离为变量，针对横向动量处于1~63 GeV区间、匹配至横向动量126~316 GeV且喷注快度绝对值小于1.7的喷注对应的带电粒子给出。

通过与质子-质子碰撞的测量结果取比值，可量化所测分布的修正效应。观测发现，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，在距喷注轴角距离不超过r=0.05的喷注核心区域内，铅-铅碰撞中的产额有所提升，但在更大角距离处则表现出产额抑制现象。