暴胀后再加热期间的熵产生与广义相对论熵加速度
Entropy production during reheating after inflation and General Relativistic Entropic Acceleration
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中文总结 AI 辅助
本文通过晶格模拟计算暴胀后预加热的相空间熵产生，并利用广义相对论熵加速度框架揭示熵产生驱动的加速度主要取决于热量而非熵本身。
中文摘要 AI 辅助
预加热将暴胀后暴胀子凝聚体的相干低熵能量转化为远离平衡的场量子浴，因此本质上是一个不可逆过程。我们通过使用CosmoLattice进行的经典统计晶格模拟计算场涨落的粗粒化相空间熵，直接量化了这种不可逆性。对于每个场，我们重建了模式占据数$n_k$，并评估$S=\sum_k[(1+n_k)\ln(1+n_k)-n_k\ln n_k]$，跟踪其在自洽膨胀的Friedmann-Lemaître-Robertson-Walker背景下再加热不同阶段的增长。我们研究了通过$g^2\phi^2\chi^2$耦合到子标量$\chi$的三个典型模型。我们讨论了晶格初始条件固有的紫外真空基底，并论证产生的熵$\Delta S$是物理上稳健的诊断量。因此，相空间熵提供了一种紧凑的动态度量，能够清晰区分预加热的共振主导、湍流主导和旋节线分解区域。我们通过广义相对论熵加速度（GREA）框架将这种熵产生耦合回膨胀，修改CosmoLattice的自洽尺度因子演化以包含熵力。由此产生的加速度跟踪热量（转移到粒子的能量）而非熵本身：在tachyonic和四次湍流情况下，相干能量的$\mathcal{O}(1)$比例碎片化为辐射，加速度显著；而在共振的$m^2\phi^2$模型中，尽管熵产生丰富，加速度却可忽略。随后缓慢的微扰再加热产生了宇宙熵的主体（$S_0 \sim10^{88}$），但未驱动明显的加速度，并在热化时完全关闭。
英文摘要
Preheating transforms the coherent, low-entropy energy of the post-inflationary inflaton condensate into a far-from-equilibrium bath of field quanta, and is therefore an intrinsically irreversible process. We quantify that irreversibility directly, by computing the coarse-grained phase-space entropy of the field fluctuations from classical-statistical lattice simulations performed with CosmoLattice. For each field we reconstruct the mode occupation numbers $n_k$ and evaluate $S=\sum_k[(1+n_k)\ln(1+n_k)-n_k\ln n_k]$, following its growth through the different stages of reheating in a self-consistently expanding Friedmann-Lemaître-Robertson-Walker background. We study three canonical models coupled to a daughter scalar $χ$ through $g^2ϕ^2χ^2$. We discuss the ultraviolet vacuum floor intrinsic to the lattice initial conditions and argue that the produced entropy $ΔS$ is the physically robust diagnostic. The phase-space entropy thus provides a compact, dynamical measure that cleanly separates the resonance-dominated, turbulence-dominated, and spinodal regimes of preheating. We couple this entropy production back into the expansion through the general relativistic entropic acceleration (GREA) framework, modifying the self-consistent scale-factor evolution of CosmoLattice to include the entropic force. The resulting acceleration tracks the heat (the energy transferred to particles) rather than the entropy itself: it is substantial in the tachyonic and quartic-turbulent cases, where an $\mathcal{O}(1)$ fraction of the coherent energy fragments into radiation, but negligible in the resonant $m^2ϕ^2$ model despite its copious entropy production. The slow perturbative reheating that follows generates the bulk of the cosmic entropy ($S_0 \sim10^{88}$) yet drives no appreciable acceleration and shuts off entirely at thermalization.
发表机构
- Instituto de Física Teórica UAM-CSIC, Universidad Autonóma de Madrid（马德里自治大学-西班牙国家科学研究委员会理论物理研究所）
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