QCD phase structure at finite temperature and density

理解极端条件下强相互作用物质的性质和可能的相是高能物理的重大挑战之一。在极早期的宇宙中，数万亿开尔文的热强相互作用物质是普遍存在的，类似的条件可以通过粒子加速器中的重离子碰撞来创造，比如日内瓦欧洲核子研究中心的大型强子对撞机（LHC）中的铅离子，以及布鲁克海文国家实验室（BNL）的相对论重离子对撞机（RHIC）中的金离子。另一方面，在中子星中可以找到与原子核相同数量级的密度，RHIC的束流能量扫描计划和高接受双电子能谱仪（HADES）以及达姆施塔特的Gesellschaft für Schwerionenforschung的计划中的反质子和离子研究设施（FAIR）研究了类似密度的物质。强相互作用物质由量子色动力学（量子色动力学（QCD）及其作为温度和密度函数的行为总结在QCD相图中。虽然在过去的几十年里已经取得了很大的进展，但在中密度和高密度下强相互作用物质的性质仍然不能用第一性原理计算，本项目的主要目标是对QCD相图的无模型参数研究。特别重点将放在数量上，可访问的实验和重要的重离子碰撞的现象学描述。这些包括保守电荷的波动，这是重离子碰撞实验。此外，将计算状态方程，它为重离子碰撞动力学的流体动力学模拟提供了重要的输入。这些现象学上重要的数量将计算的帮助下的功能重整化群（FRG）方程。以前的研究将推广到非零温度和密度。

Understanding the properties and possible phases of strongly-interacting matter under extreme conditions is one of the big challenges of high-energy physics. Hot strongly-interacting matter of several trillion Kelvin was prevalent in the very early universe and similar conditions can be created by colliding heavy ions in particle accelerators, like lead ions at the Large Hadron Collider (LHC) at CERN, Geneva, and gold ions at the Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Lab (BNL). On the other hand, densities of the same order of magnitude as present in atomic nuclei can be found in neutron stars, and similar densities are investigated in the Beam Energy Scan program at RHIC and the High Acceptance DiElectron Spectrometer (HADES) as well as the planned Facility for Antiproton and Ion Research (FAIR) of the Gesellschaft für Schwerionenforschung in Darmstadt.Strongly-interacting matter is described by Quantum Chromodynamics (QCD) and its behaviour as a function of temperature and density is summarised in the QCD phase diagram. Although much progress has been made in the last decades, the properties of strongly-interacting matter at intermediate and high densities are still not calculable from first principles.The main objective of this project is a model-parameter free investigation of the phase diagram of QCD. Particular focus will be put on quantities that are accessible to experiments and important for the phenomenological description of heavy-ion collisions. These include fluctuations of conserved charges, which are accessible to heavy-ion collision experiments. Furthermore, the equation of state, which provides an important input for hydrodynamic simulations of the dynamics of heavy-ion collisions, will be computed. These phenomenologically important quantities will be calculated with the help of the functional renormalisation group (FRG) equation. Previous investigations will be generalised to non-vanishing temperatures and densities.