Leonhardt M, Pospiech M, Schallmo B, Braun J, Drischler C, Hebeler K, Schwenk A
Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany.
ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Planckstraße 1, D-64291 Darmstadt, Germany.
Phys Rev Lett. 2020 Oct 2;125(14):142502. doi: 10.1103/PhysRevLett.125.142502.
We study the equation of state of symmetric nuclear matter at zero temperature over a wide range of densities using two complementary theoretical approaches. At low densities, up to twice nuclear saturation density, we compute the energy per particle based on modern nucleon-nucleon and three-nucleon interactions derived within chiral effective field theory. For higher densities, we derive for the first time constraints in a Fierz-complete setting directly based on quantum chromodynamics using functional renormalization group techniques. We find remarkable consistency of the results obtained from both approaches as they come together in density and the natural emergence of a maximum in the speed of sound c_{S} at supranuclear densities. The presence of this maximum appears tightly connected to the formation of a diquark gap. Notably, this maximum is observed to exceed the asymptotic value c_{S}^{2}=1/3 while its exact position in terms of the density cannot yet be determined conclusively.
我们使用两种互补的理论方法，在很宽的密度范围内研究零温度下对称核物质的状态方程。在低密度下，直至两倍核饱和密度，我们基于在手征有效场论中导出的现代核子 - 核子和三核子相互作用来计算每粒子能量。对于更高密度，我们首次在费尔斯完备的设定下，直接基于量子色动力学使用泛函重整化群技术导出约束条件。我们发现，从这两种方法得到的结果在密度上呈现出显著的一致性，并且在超核密度下声速(c_{S})自然地出现最大值。这个最大值的出现似乎与双夸克能隙的形成紧密相关。值得注意的是，观察到这个最大值超过了渐近值(c_{S}^{2}=1/3)，而其在密度方面的确切位置尚未能最终确定。
