具有横向空间梯度的boost不变等离子体中的绝热水动力学化
Adiabatic hydrodynamization with transverse spatial gradients in boost-invariant plasmas
浏览论文内容
中文总结 AI 辅助
该研究通过引入横向梯度模式，探讨了夸克-胶子等离子体快速水动力学化的机制，发现梯度耦合在后期驱动系统趋向全局吸引子，并揭示了谱隙闭合条件。
中文摘要 AI 辅助
相对论粘性流体动力学在描述短寿命夸克-胶子等离子体方面的定量成功提出了一个基本问题：远离平衡态的QCD物质如何如此迅速地接近流体动力学行为？微观动力学理论研究已将此起始过程与吸引子动力学联系起来，但通常假设横向均匀性。我们通过引入具有有限横向波数$k$的梯度模式来放宽这一假设，扩展了arXiv:2212.00820的分析。这些模式耦合了动量分布的不同球谐函数，由此产生的动力学由膨胀率$1/\ au$、碰撞率$1/\ au_R$和梯度尺度$k$之间的竞争控制。在早期，纵向膨胀抑制了这种耦合，不同的球谐函数扇区遵循其均匀吸引子。我们发现，在较晚时刻且$k$足够小时，这种梯度耦合驱动系统趋向于由流体动力学声模式和剪切模式张成的全局吸引子流形，其时间尺度$\ au_D$取决于方位角谐波$m$和$k\ au_R$。对于足够大的$k\ au_R$，谱隙闭合：微扰保持有限的阻尼率并因此达到平衡，但不再遵循孤立的水动力学吸引子，也不允许仅涉及少数流体动力学模式的约化描述。
英文摘要
The quantitative success of relativistic viscous hydrodynamics in describing the short-lived quark--gluon plasma raises a fundamental question: how does far-from-equilibrium QCD matter approach hydrodynamic behavior so rapidly? Microscopic kinetic-theory studies have related this onset to attractor dynamics, but typically assume transverse homogeneity. We relax this assumption by introducing gradient modes with finite transverse wave number $k$, extending the analysis of arXiv:2212.00820. These couple different spherical harmonics of the momentum distribution, and the resulting dynamics is controlled by the competition among the expansion rate $1/τ$, the collision rate $1/τ_R$, and the gradient scale $k$. At early times, longitudinal expansion suppresses this coupling, and different spherical harmonic sectors follow their homogeneous attractors. We find that, at later times and sufficiently small $k$, this gradient coupling drives the system toward a global attractor manifold spanned by hydrodynamic sound and shear modes, on a timescale $τ_D$ that depends on both the azimuthal harmonic $m$ and $kτ_R$. For sufficiently large $kτ_R$, the spectral gap closes: perturbations retain finite damping rates and therefore equilibrate, but no longer follow an isolated hydrodynamic attractor or admit a reduced description involving only a few hydrodynamic modes.
发表机构
- Universität Heidelberg（海德堡大学）
- Central China Normal University（华中师范大学）
- Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）
机构由 AI 辅助整理，请以论文原文为准。
