从pQCD到中子星：匹配状态方程以约束全局星性质
From pQCD to neutron stars: matching equations of state to constrain global star properties
摘要：
零温量子色动力学（QCD）的状态方程（EoS）可以在两种不同的微扰体系下计算：对于重子化学势$μ$的小值，可以用手征微扰理论（ChEFT）;对于$μ$的大值，可以用微扰QCD（pQCD）。然而，对于$μ\in (0.97\text{ GeV},\, 2.6\text{ GeV})$来说，存在一个缺口，在那里这些理论变得非微扰，并且目前还没有已知的QCD物质的微观描述。不幸的是，这个间隔掩盖了在中子星（NS）核心内发现的$μ$值。在这篇论文中，我们认为，热力学匹配的ChEFT和pQCD EoS是一个合法的方式来获得定量约束的非微扰QCD EoS。此外，我们认为，这种方法是有效的，可验证的，系统地改进。首先，我们进行了一个简化的匹配过程中的QCD类理论，可以模拟的晶格上没有一个符号的问题。我们计算的压力带可以作为格子QCD从业者的预测，并允许他们验证或反驳简化的程序。其次，我们将Kurkela等人（2014）的最先进的匹配EoS应用于旋转NS。这使我们能够获得可观察到的NS属性的界限，以及指向未来的观察，将更严格地约束当前最先进的EoS带。最后，作为改进程序的能力的证据，我们在pQCD中进行了计算，以提高零温压力。我们计算了$n_{f}$无质量夸克的全部$\mathcal{O}(g^{6} \ln^{2} g)$对pQCD压力的贡献，以及$\mathcal{O}(g^{6} \ln g)$部分的重要部分，甚至部分$\mathcal{O}(g^{6})$部分。
英文摘要：
The equation of state (EoS) of quantum chromodynamics (QCD) at zero temperature can be calculated in two different perturbative regimes: for small values of the baryon chemical potential $μ$, one may use chiral perturbation theory (ChEFT); and for large values of $μ$, one may use perturbative QCD (pQCD). There is, however, a gap for $μ\in (0.97\text{ GeV},\, 2.6\text{ GeV})$, where these theories becomes non-perturbative, and where there is currently no known microscopic description of QCD matter. Unfortunately, this interval obscures the values of $μ$ found within the cores of neutron stars (NSs). In this thesis, we argue that thermodynamic matching of the ChEFT and pQCD EoSs is a legitimate way to obtain quantitative constraints on the non-pertubative QCD EoS. Moreover, we argue that this method is effective, verifiable, and systematically improvable. First, we carry out a simplified matching procedure in QCD-like theories that can be simulated on the lattice without a sign problem. Our calculated pressure band serves as a prediction for lattice-QCD practitioners and will allow them to verify or refute the simplified procedure. Second, we apply the state-of-the-art matched EoS of Kurkela et al. (2014) to rotating NSs. This allows us to obtain bounds on observable NS properties, as well as point towards future observations that would more tightly constrain the current state-of-the-art EoS band. Finally, as evidence of the ability to improve the procedure, we carry out calculations in pQCD to improve the zero-temperature pressure. We calculate the full $\mathcal{O}(g^{6} \ln^{2} g)$ contribution to the pQCD pressure for $n_{f}$ massless quarks, as well as a significant portion of the $\mathcal{O}(g^{6} \ln g)$ piece and even some of the $\mathcal{O}(g^{6})$ piece.
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