RUI: Dissipative Dynamics of the Quark Gluon Plasma

RUI：夸克胶子等离子体的耗散动力学

• 批准号: 1068765
• 负责人: Michael Strickland
• 金额: $ 14.1万
• 依托单位: Gettysburg College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-15 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1068765&HistoricalAwards=false
• 关键词: RUI; Dissipative; Dynamics; Quark; Gluon

An understanding of why the universe is the way it is right now depends critically on our understanding of the various phase transitions that have occurred since the beginning of time until now. A key phase transition in this chain is called the quark gluon plasma (QGP) phase transition. This phase transition has the distinction of being the only one that is experimentally accessible using the current generation of particle accelerators. Experiments already performed at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab have reached the temperature necessary to trigger the emergence of a quark-gluon plasma; however, the temperatures generated were only slightly higher than the phase transition temperature of 2 trillion degrees K. Experiments recently carried out at higher collision energies at the Large Hadron Collider (LHC) and CERN have generated states with temperatures approaching four times the critical temperature for the transition to the plasma phase. A large part of the QGP-physics theoretical effort is dedicated to describing the thermalization and subsequent evolution of the matter produced using viscous hydrodynamical models. The success of these models to describe the collective flow of the matter created during heavy ion collisions at RHIC is remarkable. It seems that the data for the elliptic flow of the particles created during the event is compatible with the matter having a small shear viscosity approaching the limit of a "perfect fluid." However, key uncertainties still remain in the application of viscous hydrodynamical models that may impact upcoming experiments at the Large Hadron Collider (LHC). One of the primary uncertainties centers on the question of when is the appropriate time to begin a viscous hydrodynamical description of the matter that is created in the collision. Traditional viscous hydrodynamical treatments rely on an implicit assumption that the system is very close to thermal equilibrium and isotropy in momentum space. In practice, the evolution of the deviations from a thermal isotropic state is described by viscous hydrodynamical evolution. However, such descriptions can break down at the earliest times after the collision due to the presence of large momentum-space anisotropies. In this work I will extend and develop a new method for deriving dynamical equations for the evolution of the quark gluon plasma which relaxes one of the assumptions implicit in hydrodynamical descriptions, namely the assumption that the system is nearly isotropic in momentum space. The new method reorganizes the expansion of the one particle distribution function around an anisotropic state described by space-time dependent ellipticities and an anisotropic temperature. The resulting coupled partial differential equations can be used to describe the evolution of the system during the entire history of the quark gluon plasma. The research funded should have a significant impact on our understanding the non-equilibrium dynamics of ultrarelativistic systems. There is also an overarching educational goal to involve undergraduate physics majors in an active research program. The proposal involves the inclusion of two undergraduate research assistants who will receive training in analytic and numerical methods. This kind of training is crucial to the future success of the United States scientific programs and to attracting talented students to scientific careers.

了解宇宙为什么现在的方式取决于我们对自到现在开始以来发生的各种阶段过渡的理解。 该链中的关键相变称为Quark Gluon等离子体（QGP）相变。 这种相变的区别是，使用当前产生的粒子加速器可以在实验上访问的相位。 在布鲁克黑文国家实验室的相对论重离子对撞机（RHIC）已经进行的实验已经达到了触发夸克 - 粘液等离子体出现所需的温度。然而，产生的温度仅略高于2万亿度K的相变温度。最近在大型强子撞机（LHC）的较高碰撞能量（LHC）上进行的实验，并且CERN产生的状态已产生，温度接近四倍的临界温度，用于过渡到等离子相。 QGP物理学理论上的很大一部分致力于描述使用粘性流体动力学模型产生的物质的热化和后续演变。 这些模型描述在RHIC重离子碰撞期间产生的物质的集体流动的成功是显着的。 似乎在事件期间产生的颗粒的椭圆流的数据与具有较小的剪切粘度接近“完美流体”的限制的物质兼容。 但是，在应用粘性流体动力学模型的应用中仍然存在关键的不确定性，这些模型可能会影响大型强子对撞机（LHC）的即将进行的实验。主要的不确定性之一集中在何时开始对碰撞中创建的物质进行粘性水动力描述的问题。传统的粘性水动力处理依赖于隐式假设，即该系统非常接近动量空间中的热平衡和各向同性。 实际上，通过粘性流体动力学进化来描述与热各向同性状态的偏差的演变。 但是，由于存在较大的动量空间各向异性，这种描述可能会在碰撞后的最早崩溃。 在这项工作中，我将扩展并开发一种新方法，用于得出动态方程，以放宽流体动力描述中隐含的假设之一，即假设系统在动量空间中几乎是各向同性的假设。 新方法重新组织了一个粒子分布函数在各向异性状态周围的扩展，由时空依赖性椭圆率和各向异性温度描述。 所得的耦合部分微分方程可用于描述在夸克Gluon等离子体的整个历史中系统的演变。资助的研究应该对我们理解超层次主义系统的非平衡动态产生重大影响。 还有一个总体的教育目标，可以让本科物理专业的专业参加活跃的研究计划。该提案涉及包括两名将接受分析和数值方法培训的本科研究助理。 这种培训对于美国科学计划的未来成功以及吸引才华横溢的学生从事科学职业至关重要。