Jet-like correlations with neutral pion triggers in pp and central Pb–Pb collisions at 2.76 TeV
Jet-like correlations with neutral pion triggers in pp and central Pb–Pb collisions at 2.76 TeV
复制标题
2.76 TeV 的 pp 和中心 Pb−Pb 碰撞中与中性 pion 触发的射流相关性
DOI：
10.1016/j.physletb.2016.10.048
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发表时间：
2016
影响因子：
4.4
通讯作者：
X. Peng 核心分析作者
中科院分区：
文献类型：
--
作者：
ALICE Collaboration;Y. Mao课题组织者及主要参与者;X. Peng 核心分析作者
本文用ALICE测量了横动量为8< ptrigT<16 GeV/c的中性π触发粒子和0.5< passocT<10 GeV/c的带电粒子在pp和中心Pb-Pb碰撞中的中快度两粒子关联与方位角差θ的关系。新的测量利用了低至0.5 GeV/c的相关带电强子，这大大扩展了我们以前的测量，仅使用3GeV/c以上的带电强子。在减去流动背景的贡献v2至v5之后，提取每个触发器的产量，| ϕ| < 0.7在附近和| ϕ− π| < 1.1在远方测量了Pb-Pb碰撞中0-10%最中心Pb-Pb碰撞的近侧和远侧的每触发产额与pp碰撞中的每触发产额之比IAA。在远场，当PassocT> 3GeV/c时，Pb-Pb的每次触发产额被强烈抑制到IAA ~（10）0.6的水平，而随着动量的减小，在低PassocT时，每次触发产额增加到约50。在近侧，观察到IAA在最高1.2至最低1.8之间增强。数据进行比较的JEWEL和AMPT事件发生器的部分子能量损失的预测，以及微扰QCD计算与中等修改的碎裂功能。所有的计算定性地描述了在高passocT远离侧抑制。只有AMPT在近侧和远侧均捕获低通道时的增强。然而，它也低估了5GeV/c以上的IAA，特别是在近侧。
We present measurements of two-particle correlations with neutral pion trigger particles of transverse momenta 8< ptrigT< 16GeV/cand associated charged particles of 0.5< passocT< 10GeV/cversus the azimuthal angle difference ϕat midrapidity in pp and central Pb–Pb collisions at√ sNN= 2.76 TeVwith ALICE. The new measurements exploit associated charged hadrons down to 0.5 GeV/c, which significantly extends our previous measurement that only used charged hadrons above 3GeV/c. After subtracting the contributions of the flow background, v2to v5, the per-trigger yields are extracted for| ϕ|< 0.7 on the near and for| ϕ− π|< 1.1 on the away side. The ratio of per-trigger yields in Pb–Pb to those in pp collisions, IAA, is measured on the near and away side for the 0–10% most central Pb–Pb collisions. On the away side, the per-trigger yields in Pb–Pb are strongly suppressed to the level of IAA≈ 0.6 for passocT> 3GeV/c, while with decreasing momenta an enhancement develops reaching about 5at low passocT. On the near side, an enhancement of IAAbetween 1.2 at the highest to 1.8 at the lowest passocTis observed. The data are compared to parton-energy-loss predictions of the JEWEL and AMPT event generators, as well as to a perturbative QCD calculation with medium-modified fragmentation functions. All calculations qualitatively describe the away-side suppression at high passocT. Only AMPT captures the enhancement at low passocT, both on the near and away side. However, it also underpredicts IAAabove 5GeV/c, in particular on the near-side.