Using Jets as a Probe of the Quark Gluon Plasma

构成物质的质子和中子是由较小的成分组成的，这些成分被称为夸克和胶子。在加速到接近光速的重核碰撞中，形成了一种新的物质状态，称为夸克-胶子等离子体(QGP)。在这件事上，质子和中子似乎都会融化，让夸克和胶子形成一种汤状的相，粘度几乎是尽可能低的，这为它赢得了完美液体的称号。这个项目将回答有关QGP的基本问题，例如正常物质是如何形成的，以及它是如何从大爆炸后存在的原始物质汤进化而来的。该项目的目标是探索QGP的内部工作原理，并通过使用重核碰撞中夸克的高动量碰撞来确定其在短得多的长度尺度上的性质。这项研究将在位于布鲁克海文国家实验室的相对论重离子对撞机(RHIC)的恒星探测器上进行。该奖项还将支持国际和平协会对研究生和本科生的指导，并通过外联活动扩大代表不足群体的人在STEM的参与。粒子喷流是在重核碰撞的最初阶段形成的，当时两个夸克或胶子有很高的动量碰撞。在这次碰撞中，它们被踢向相反的方向，大致垂直于重离子粒子束。这种相互作用产生的夸克和胶子将穿过QGP，与之相互作用，并向其损失能量。然后，它们碎裂并被强电子化成一束粒子，可以由恒星上的探测器测量到。粒子喷流的能量尺度与它能探测到的长度尺度成反比。这项工作将集中在与RHIC顶层碰撞能量的即时光子-喷流关联相关的可观测性上。这类观测的优点是，由于动量守恒和光子与QGP的不相互作用，产生这些碰撞的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，从而理解强核力是如何运作的。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The building blocks of matter, protons and neutrons, are made up of smaller constituents, which are called quarks and gluons. In collisions of heavy nuclei accelerated to nearly the speed of light, a new state of matter is formed, called the quark-gluon plasma (QGP). In this matter, the protons and neutrons seem to "melt", allowing the quarks and gluons to form a soup-like phase with a viscosity that is nearly as low as possible, earning it the title of a perfect liquid. This project will answer fundamental questions about the QGP, such as how normal matter came into being and how it evolved from the primordial soup of matter which existed just after the Big Bang. The goal of the project is to probe the inner workings of the QGP and determine its properties at much shorter length scales by using high momentum collisions of quarks from within the heavy nuclei collisions. This research will be performed with the STAR detector at the Relativistic Heavy Ion Collider (RHIC), which is located at Brookhaven National Laboratory. This award will also support the PI's mentoring of graduate students and undergraduate students as well as broadening the participation of people from underrepresented groups in STEM through outreach activities. Particle jets are formed in the very initial stages of the heavy nuclei collision, when two quarks or gluons have a high momentum collision. In this collision they are kicked in opposite directions from one another, roughly perpendicular to the beam of heavy ion particles. The quarks and gluons from such an interaction will travel through the QGP, interacting with and losing energy to it. They then fragment and hadronize into a spray of particles which can be measured by the detectors at STAR. The energy scale of the particle jet is inversely proportional to the length scale that it can probe. This effort will focus on observables related to prompt photon-jet correlations at the top collision energies at RHIC. Observables in this category have the advantage that the transverse momentum of jets produced these collisions is explicitly known, due to both conservation of momentum, and the non-interaction of the photon with the QGP. These measurements will be necessary to understand the temperature and energy dependence of key features of theoretical models of the quark-gluon interactions, and thus understand how the strong nuclear force operates.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.