标题： 基于最新格点QCD状态方程的宇宙轨迹计算 显示英文标题

标题： Cosmic Trajectories calculation with state of the art lattice QCD equation of state

摘要： 我们计算了早期宇宙在整个QCD相图中的完整宇宙轨迹，当等离子体从$T\simeq500\,$MeV 冷却到$30\,$MeV，假设$\beta$平衡的物质。 这些轨迹是通过同时求解重子数、电荷和轻子不对称性守恒得到的，并由最先进的格点QCD状态方程闭合：一种四阶泰勒展开在化学势中，结合了最新$(2\!+\!1)$重味灵敏度与魅夸克贡献，从而提供了一个一致的$(2\!+\!1\!+\!1)$重味状态方程。 结果与理想夸克-胶子等离子体和强子共振气体进行比较，以突出相互作用效应。 分析了两种原始轻子不对称情况：对称配置$(\ell_e=\ell_\mu=\ell_\tau=\ell/3)$和非对称配置$(\ell_e=0,\;\ell_\mu=-\ell_\tau)$。 系统地增加$|\ell|$会将轨迹引向更大的$\mu_B$值和更负的$\mu_Q$。 在非对称情况下，当$\tau$化学势达到$m_\tau$时会出现非单调的反弹，在$\mu_B(T)$中产生一个最大值，其位置取决于$\ell_\tau$。 假设格点QCD临界端点估计值（在$\mu_{Q} = 0$处获得）对$\mu_{Q}$的依赖性较小，那么所有轻子不对称性的轨迹（$|\ell|\lesssim 0.1$）都位于其左侧，这意味着在标准宇宙学情景下，QCD转变几乎可以肯定是一个平滑的交叉。然而，我们估算出需要的重子和轻子不对称性的大小，以获得更接近QCD临界点的宇宙轨迹，并为强相互作用时期的未来研究提供输入。 显示英文摘要

摘要： We compute the full cosmic trajectories of the early Universe across the QCD phase diagram as the plasma cools from $T\simeq500\,$MeV to $30\,$MeV, assuming $\beta$-equilibrated matter. The trajectories are obtained by simultaneously solving baryon-number, electric-charge, and lepton-asymmetry conservation, closed by a state-of-the-art lattice-QCD equation of state: a fourth-order Taylor expansion in the chemical potentials that merges the latest $(2\!+\!1)$-flavor susceptibilities with charm-quark contributions, thus delivering a consistent $(2\!+\!1\!+\!1)$-flavor equation of state. Results are compared with an ideal quark-gluon plasma and with a hadron-resonance gas to highlight interaction effects. Two cases of primordial lepton asymmetries are analyzed: a symmetric configuration $(\ell_e=\ell_\mu=\ell_\tau=\ell/3)$ and an asymmetric one $(\ell_e=0,\;\ell_\mu=-\ell_\tau)$. Increasing $|\ell|$ systematically drives the trajectories toward larger values of $\mu_B$ and more negative $\mu_Q$. In the asymmetric case, a non-monotonic bounce develops when the $\tau$ chemical potential reaches $m_\tau$, generating a maximum in $\mu_B(T)$, the position of which depends on $\ell_\tau$. Assuming a modest $\mu_{Q}$-dependence of the lattice-QCD critical end point estimates (obtained at $\mu_{Q} = 0$), the trajectories for all lepton asymmetries explored ($|\ell|\lesssim 0.1$) lie to their left, implying that in a standard cosmological scenario the QCD transition is almost certainly a smooth crossover. Nevertheless, we estimate the magnitude of baryon and lepton asymmetries needed to obtain a cosmic trajectory closer to the QCD critical point, providing inputs for future studies of the strong-interaction epoch.