论文标题
QCD手性跨界的斜谱特性
Pion spectral properties above the chiral crossover of QCD
论文作者
论文摘要
光谱函数编码有关任何给定系统动力学的大量信息，并且确定其非扰动特征是量子场理论中的长期问题。晶格QCD的数值模拟为各种欧几里得相关函数提供了足够的数据，但提取光谱函数所需的反演是一个不足的问题。在这项工作中，我们追求了先前在有限温度下的现场区域施加的约束，即光谱函数具有非扰动表示，该表示将众所周知的Källén-Lehmann光谱形式泛化至$ t> 0 $。使用此表示，我们分析了温度范围内空间伪量表相关器的晶格QCD数据$ 220-960 \，\ text {Mev} $，并获得相应光谱函数的分析表达式，并带有数据固定的参数。从该光谱函数的结构中，我们找到了在手性伪临界温度上方存在明显的旋转状态的证据，$ t _ {\ text {pc}} $以及其第一个激发的贡献，随着温度的增加，其首次激发逐渐融化。作为非平凡测试，我们发现提取的光谱函数重现了$ t = 220 \，\ text {mev} $的相应时间晶格相关数据。
Spectral functions encode a wealth of information about the dynamics of any given system, and the determination of their non-perturbative characteristics is a long-standing problem in quantum field theory. Whilst numerical simulations of lattice QCD provide ample data for various Euclidean correlation functions, the inversion required to extract spectral functions is an ill-posed problem. In this work, we pursue previously established constraints imposed by field locality at finite temperature $T$, namely that spectral functions possess a non-perturbative representation which generalises the well-known Källén-Lehmann spectral form to $T>0$. Using this representation, we analyse lattice QCD data of the spatial pseudo-scalar correlator in the temperature range $220-960 \, \text{MeV}$, and obtain an analytic expression for the corresponding spectral function, with parameters fixed by the data. From the structure of this spectral function we find evidence for the existence of a distinct pion state above the chiral pseudo-critical temperature $T_{\text{pc}}$, and contributions from its first excitation, which gradually melt as the temperature increases. As a non-trivial test, we find that the extracted spectral function reproduces the corresponding temporal lattice correlator data for $T=220 \, \text{MeV}$.
