AI 中文总结
该研究提出了一类物质 sector 含优先空间方向却具 FLRW 几何的宇宙学场景，通过矢量场方程与相互作用实现宇宙学原理，其扰动的混合通道可使标量扰动产生引力波，揭示了优先方向物理留可观测信号的新途径。
AI 中文摘要
我们提出一类宇宙学场景，其中物质 sector 中的优先空间方向与严格均匀且各向同性的弗里德曼-勒梅特-罗伯逊-沃尔克（FLRW）几何共存。宇宙学原理在壳上实现，矢量场方程要求动量密度为零，且合适的相互作用消除了各向异性应力。因此，该构造产生了一整个 FLRW 分支，无需微调物质场初始条件。优先方向在扰动中重新出现，在标量、矢量和张量模式之间产生线性阶就存在的方向相关传播与混合。特别是，这种混合打开了一个线性通道，标量 sector 中的扰动原则上可通过该通道产生引力波。我们的构造因此揭示了一条新途径，通过该途径，优先方向物理可留下可观测的宇宙学信号，同时在背景几何中保持隐藏状态。
英文摘要
We present a class of cosmological scenarios in which a preferred spatial direction in the matter sector coexists with an exactly homogeneous and isotropic Friedmann--Lema\^ıtre--Robertson--Walker (FLRW) geometry. The Cosmological Principle is realized on shell, with the vector-field equations enforcing a vanishing momentum density and suitable interactions eliminating the anisotropic stress. Consequently, the construction yields an entire FLRW branch without tuning the matter-field initial conditions. The preferred direction reemerges in perturbations, producing direction-dependent propagation and mixing among scalar, vector, and tensor modes already at linear order. In particular, the mixing opens a linear channel through which perturbations in the scalar sector can in principle source gravitational waves. Our construction thus reveals a new route by which preferred-direction physics can leave observable cosmological signatures while remaining hidden in the background geometry.
Comments7 pages,1 Figure
