AI 中文总结
研究构建零化学势下强相互作用物质状态方程，用强子和部分子自由度统一描述晶格QCD热力学，通过拟合晶格QCD结果确定模型参数，再现相关数据，发现强子到部分子自由度转变更渐进，高温下强子态仍是重要组成部分。
AI 中文摘要
我们构建了一个零化学势下强相互作用物质的简单状态方程，它从强子和部分子自由度方面统一描述了晶格QCD热力学。强子相由量子范德瓦尔斯强子共振气体描述，并通过介子间的排除体积排斥进行扩展，夸克-胶子等离子体被建模为夸克和胶子的理想气体并补充了一个与\(T^3\)成比例的唯象相互作用项。两种状态通过一个平滑的交叉切换函数相连。通过与晶格QCD结果拟合确定了三个模型参数。所得状态方程再现了温度范围\(T = 100 - 500\)MeV内的压力、熵密度、能量密度和声速的晶格数据。拟合得出介子硬核半径\(r_M \simeq 0.2\)fm、部分子相互作用尺度\(A \simeq 600\)MeV和切换温度\(T_0 \simeq 216\)MeV。这表明从强子到部分子自由度的转变比仅由手征伪临界温度所表明的更为渐进，强子态在高达约250MeV的温度下仍是强相互作用物质的重要组成部分，远高于QCD手征交叉温度。
英文摘要
We construct a simple equation of state of strongly interacting matter at zero chemical potentials that provides a unified description of lattice QCD thermodynamics in terms of hadronic and partonic degrees of freedom. The hadronic phase is described by the quantum van der Waals hadron resonance gas, extended by excluded-volume repulsion between mesons, while the quark-gluon plasma is modeled as an ideal gas of quarks and gluons supplemented with a phenomenological interaction term proportional to $T^3$. The two regimes are connected by a smooth crossover switching function. The three model parameters - the meson hard-core radius, the strength of the partonic interaction term, and the switching temperature - are determined from a fit to lattice QCD results for the trace anomaly. The resulting equation of state reproduces the lattice data on the pressure, entropy density, energy density, and speed of sound in the temperature range $T=100$-$500$ MeV. The fit yields a meson hard-core radius $r_M \simeq 0.2$ fm, a partonic interaction scale $A \simeq 600$ MeV, and a switching temperature $T_0 \simeq 216$ MeV, substantially exceeding both the pseudocritical temperature of the QCD chiral crossover and the chemical freeze-out temperature. This finding suggests that the transition from hadronic to partonic degrees of freedom is considerably more gradual than indicated by the chiral pseudocritical temperature alone, with hadronic states remaining an important component of strongly interacting matter up to temperatures of about $250$ MeV, well above the QCD chiral crossover.
Comments11 pages, 5 figures
