O (α s 3 ) analysis of inclusive jet and di-jet production in heavy ion reactions at the Large Hadron Collider
O (α s 3 ) analysis of inclusive jet and di-jet production in heavy ion reactions at the Large Hadron Collider
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DOI：
10.1016/j.physletb.2012.05.054
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发表时间：
2011-05
影响因子：
4.4
通讯作者：
Yuncun He;I. Vitev;Ben-Wei Zhang
中科院分区：
文献类型：
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作者：
Yuncun He;I. Vitev;Ben-Wei Zhang
重离子反应中的射流物理是相对论重离子对撞机（RHIC）和大型强子对撞机（LHC）活跃研究的一个重要新领域，它为致密核物质中QCD多部分动力学的新测试铺平了道路。目前，基本核子-核子反应中硬探针的微扰QCD计算可以一致地与核介质的影响结合到O（αs3）以下。虽然这样的精度是理想的，但对于领先的粒子层析成像来说不是必需的，但对于新的射流观测来说，这是绝对必要的。基于这一动机，我们首次给出了LHC铅-铅（Pb+Pb）在每核子-核子对质量中心能量为2.76 TeV时运行的结果和对O（αs3）的预测。具体来说，我们重点研究了单包流和双包流射流截面的抑制。我们的分析不仅包括QGP中的末态非弹性部分子相互作用，还包括初始态冷核物质效应和非微扰强子化修正的估计。我们证明了最近通过ATLAS和CMS实验测量的LHC中心Pb+Pb反应中增强的双射流不对称性是如何从这些结果中推导出来的。我们定量地表明，这种增强的一部分可能与射流和软背景介质之间分离的模糊性和/或通过碰撞过程将部分子簇能量从射流轴扩散出去有关。我们指出了一套测量方法，可以帮助建立一个在大型强子对撞机重离子碰撞中部分子阵雨变化的一致图像。
Jets physics in heavy ion reactions is an important new area of active research at the Relativistic Heavy Ion Collider (RHIC) and at the Large Hadron Collider (LHC) that paves the way for novel tests of QCD multi-parton dynamics in dense nuclear matter. At present, perturbative QCD calculations of hard probes in elementary nucleon–nucleon reactions can be consistently combined with the effects of the nuclear medium up to O(αs3). While such accuracy is desirable but not necessary for leading particle tomography, it is absolutely essential for the new jet observables. With this motivation, we present first results and predictions to O(αs3) for the recent LHC lead–lead (Pb+Pb) run at a center-of-mass energy of 2.76 TeV per nucleon–nucleon pair. Specifically, we focus on the suppression of the single and double inclusive jet cross sections. Our analysis includes not only final-state inelastic parton interactions in the QGP, but also initial-state cold nuclear matter effects and an estimate of the non-perturbative hadronization corrections. We demonstrate how an enhanced di-jet asymmetry in central Pb+Pb reactions at the LHC, recently measured by the ATLAS and CMS experiments, can be derived from these results. We show quantitatively that a fraction of this enhancement may be related to the ambiguity in the separation between the jet and the soft background medium and/or the diffusion of the parton shower energy away from the jet axis through collisional processes. We point to a suite of measurements that can help build a consistent picture of parton shower modification in heavy ion collisions at the LHC.