论文标题
在扰动和非扰动QCD量表上对$ p $+pb碰撞的调查
Investigations of $p$+Pb Collisions at Perturbative and Non-Perturbative QCD Scales
论文作者
论文摘要
高能量核碰撞表现出各种有趣的现象。这些现象中的许多现象与被称为夸克gluon等离子体（QGP）的夸克和胶子形成的热和密集状态有关。其中的主要是QGP几乎观察到的QGP的近距离流体动力扩展，如低 - $ p_ \ p_ \ mathrm {t} $最终状态hadrons $ v_ \ mathrm {n} $的差异和高度p_ p_ \ mathrm colder as as as as as as as as as as as as as as as as as as as as as as as a as as as a s y Mathrm的降低量很少。淬灭诸如喷气机之类的强烈相互交互的最终状态对象。在RHIC和LHC的AU+AU和PB+PB碰撞中对这些现象的观察提供了令人信服的QGP形成证据。小型碰撞系统（例如$ p $+pb）也通过观察各向异性流量来显示QGP创建液滴的证据；但是，这些系统没有在大型碰撞系统中观察到的能量损失的迹象。因此，小型系统是探索高和低$ p_ \ mathrm {t} $ qGP现象之间关系的理想场所。此外，与A+A碰撞相比，$ P $+PB的低环境能量可以精确地确定扰动过程速率，该过程可用于了解核子parton密度的核修饰。 本文探讨了LHC上Atlas检测器收集的$ P $+PB数据。迅速，分离的光子的横截面和核修饰因子与扰动QCD计算的预测和初始状态损失模型进行了比较。此外，带电的强体方位角各向异性系数是通过两粒子相关性测量的，这是粒子$ p_ \ mathrm {t} $和事件中心性的函数。由于存在高$ p_ \ mathrm {t} $ jet所选择的最小偏差事件和事件，结果显示出结果。
High energy nuclear collisions manifest a variety of interesting phenomena over a broad range of energy scales. Many of these phenomena are related to the formation of a hot and dense state of deconfined quarks and gluons known as the quark gluon plasma (QGP). Chief among these are the observed near inviscid hydrodynamic expansion of the QGP, as measured through azimuthal anisotropy coefficients of low-$p_\mathrm{T}$ final state hadrons $v_\mathrm{n}$, and the loss of energy of high-$p_\mathrm{T}$ color charges as they traverse the QGP which is observed as a quenching of strongly-interacting final state objects like jets. Observations of these phenomena in Au+Au and Pb+Pb collisions at RHIC and the LHC provide compelling evidence of QGP formation. Small collision systems, like $p$+Pb, also show evidence for the creation droplets of QGP through the observation of anisotropic flow; however, these systems show no signs of the energy loss observed in large collision systems. Thus, small systems are an ideal venue to explore the relationship between high- and low-$p_\mathrm{T}$ QGP phenomena. Furthermore, the low ambient energy of $p$+Pb compared to A+A collisions allow for the precise determination of perturbative process rates which can be used to understand the nuclear modification of nucleon parton densities. This dissertation explores $p$+Pb data collected with the ATLAS detector at the LHC. The cross section and nuclear modification factor for prompt, isolated photons are measured and compared to predictions from perturbative QCD calculations and a model of initial state energy loss. Additionally, the charged hadron azimuthal anisotropy coefficients, are measured via two-particle correlations as a function of particle $p_\mathrm{T}$ and event centrality. Results are shown from minimum bias events and events selected because of the presence of a high-$p_\mathrm{T}$ jet.
