Differential Measures of Parton Energy Loss in the Quark Gluon Plasma Using Photon Jet Correlations

众所周知，质子和中子是由更小的夸克和胶子组成的。 在使用两束重核的碰撞中，形成了一种新的物质状态，称为夸克胶子等离子体（QGP）。 这个项目将回答有关QGP的基本问题，例如物质如何从质子和中子的集合转变为自由状态，夸克和胶子可以不受阻碍地穿越空间，就像它们在大爆炸后的物质原始汤中所做的那样。 该项目的目标是通过使用夸克的硬碰撞来探测这种热核介质，从而在更短的长度尺度上解决其性质，从而探测QGP的内部工作。 这项研究将在布鲁克海文国家实验室的相对论重离子对撞机（星星）的螺线管跟踪器上进行。粒子喷流是在重离子碰撞的初始阶段形成的，当两个夸克或胶子发生硬散射时，它们被踢向彼此相反的方向，大致垂直于重离子束。 在这种相互作用中被踢出的夸克和胶子将穿过介质，相互作用并失去能量，然后它们碎裂并强子化成粒子喷雾，可以被星星的探测器测量。 具体来说，这项工作将集中在与RHIC最高能量处的光子-喷流相关性有关的可观测量上。 这比其他观测量有优势，因为动量守恒和光子不与夸克胶子等离子体相互作用的事实，喷流的横向动量是明确已知的。这些测量对于理解夸克-胶子相互作用理论模型的关键特征的温度和能量依赖性是必要的。

It is a well-established fact that protons and neutrons are made up of smaller constituents called quarks and gluons. In collisions using two beams of heavy nuclei, a new state of matter is formed, called the quark-gluon plasma (QGP). This project will answer fundamental questions about the QGP, such as how matter is transformed from a collection of protons and neutrons to a free state where quarks and gluons can travel through space unhindered, much like they did in the primordial soup of matter following the Big Bang. The goal of the project is to probe the inner workings of the QGP by resolving its properties at much shorter length scales by using hard collisions of quarks to probe this hot nuclear medium. This research will be performed at the Solenoidal Tracker at the Relativistic Heavy Ion Collider (STAR), which is located at Brookhaven National Laboratory. Particle jets are formed in the very initial stages of the heavy ion collision, when two quarks or gluons have a hard scattering in which they are kicked in opposite directions from one another and roughly perpendicular to beam of heavy ion particles. The quarks and gluons that are kicked out in such an interaction will travel through the medium, interacting and losing energy to it. They then fragment and hadronize into a spray of particles that can be measured by the detectors at STAR. Specifically, the effort will concentrate on observables related to prompt photon-jet correlations at the top energies at RHIC. This has the advantage over other observables that the transverse momentum of the jet is explicitly known due to both conservation of momentum, and the fact that the photon does not interact with the Quark Gluon Plasma. These measures will be necessary to understand the temperature and energy dependence of key features of theoretical models of the quark-gluon interactions.