AI 中文总结
研究弯曲时空中多原子气体的六场有理扩展热力学模型RET$_6$，基于玻尔兹曼 - 切尔尼科夫方程扩展及最大熵封闭，证明相关不可行定理，应用于FLRW时空，引入宇宙学常数后证明德西特吸引子相关特性，数值显示膨胀历史接近$\Lambda$CDM。
AI 中文摘要
我们为相对论性多原子气体制定了一个一般协变的六场有理扩展热力学模型（RET$_6$），其中动态压力是唯一的非平衡变量。该模型基于玻尔兹曼 - 切尔尼科夫动力学方程的多原子扩展，单粒子分布还依赖于一个内能变量，以及相关相对论矩层次的最大熵封闭。由此产生的场方程、封闭关系和产生项由基础动力学结构确定，而非现象学假设。我们通过最小耦合规定将RET$_6$模型从闵可夫斯基时空扩展到一般弯曲时空，并将其与爱因斯坦方程耦合。作为第一个结构结果，我们在这种多原子RET设置中证明了一个动力学理论的不可行定理，即任何由非负相对论单粒子分布函数诱导的应力 - 能量张量都满足强能量条件。然后我们将该理论专门应用于均匀各向同性的弗里德曼 - 勒梅特 - 罗伯逊 - 沃克（FLRW）时空。在这种情况下，动态压力相对于理想流体欧拉情况修改了膨胀动力学，但不可行定理排除了仅由RET$_6$气体驱动的加速。最后，我们重新引入宇宙学常数并研究组合的$\Lambda$RET$_6$模型，证明后期德西特吸引子的存在和局部稳定性。数值积分表明，对于具有物理动机的重组后初始数据和弛豫时间，膨胀历史迅速接近$\Lambda$CDM的历史，具有由弛豫时间和动态压力初始值控制的小非平衡修正。
英文摘要
We formulate a generally covariant six-field Rational Extended Thermodynamics model (RET$_6$) for relativistic polyatomic gases, with the dynamical pressure as the only non-equilibrium variable. The model is based on a polyatomic extension of the Boltzmann-Chernikov kinetic equation, where the one-particle distribution depends also on an internal-energy variable, and on the Maximum Entropy closure of the associated relativistic moment hierarchy. The resulting field equations, closure relations, and production term are therefore fixed by the underlying kinetic structure rather than postulated phenomenologically. We extend the RET$_6$ model from Minkowski spacetime to a general curved spacetime by the minimal coupling prescription and couple it to the Einstein equations. As a first structural result, we prove a kinetic-theory no-go theorem in this polyatomic RET setting stating that any stress-energy tensor induced by a non-negative relativistic one-particle distribution function satisfies the strong energy condition. We then specialize the theory to a homogeneous and isotropic Friedmann-Lemaître-Robertson-Walker (FLRW) spacetime. In this setting the dynamical pressure modifies the expansion dynamics with respect to the perfect-fluid Euler case, but the no-go theorem excludes acceleration driven by the RET$_6$ gas alone. Finally, we reintroduce a cosmological constant and study the combined $Λ$RET$_6$ model. For the diatomic equation of state and a constant positive relaxation time, we prove the existence and local stability of a de Sitter attractor at late times. Numerical integrations show that, for representative post-recombination initial data and constant relaxation times, the expansion history rapidly approaches that of $Λ$CDM, with small non-equilibrium corrections controlled by the relaxation time and by the initial value of the dynamical pressure.
Comments24 pages, many figures, improved presentation
