AI 中文总结
研究在标量-张量引力中，通过对均匀无剪切背景的横向无迹微扰，激活局部剪切功通道，得出应力功率相关结论，展示了传播的自旋2模式可获引力热力学解释。
AI 中文摘要
在约旦框架标量-张量引力中，一个类时标量梯度定义了一种有效的热力学介质。我们表明，均匀无剪切背景的横向无迹微扰激活了局部剪切功通道\(\mathcal W_\phi=\pi_{ab}^{(\phi)}\sigma^{ab}\)，其领先的纯横向无迹贡献为\(\mathcal P_{\rm TT}^{[1,1]} =\overline{\mathcal K\mathcal T} \dot\chi_{ij}^{\rm TT}\dot\chi_{\rm TT}^{ij}/4\)。这种应力功率源于局部牵引力学，进入标量扇区能量平衡，并且在二阶时是规范不变的。相同的标量-张量耦合控制非广义相对论张量阻尼，并且在广义相对论归一化振幅平衡中以相反的符号出现，尽管其作为单独张量能量源的解释取决于归一化。因此，标量-张量引力提供了一个可控的例子，其中传播的自旋2模式获得了内在的引力热力学解释。
英文摘要
Can a propagating spin--2 mode participate in a local thermodynamic process without assigning an autonomous entropy or a unique local energy to the wave itself? We show that this occurs in Jordan-frame scalar--tensor gravity, where a timelike scalar gradient defines an internal gravitational thermodynamic medium. Building on the first-order TT deformation--response relation, we identify the local shear power $\mathcal W_ϕ=π_{ab}^{(ϕ)}σ^{ab}$ from scalar-frame traction mechanics and show that its leading pure-TT contribution is second order, gauge invariant, and enters the exact scalar-sector energy balance. We further show that the same effective anisotropic stress controls the non-GR tensor damping, so the local thermodynamic exchange is directly encoded in gravitational-wave propagation. In geometric optics the corresponding ratio of shear work to GR-normalized tensor energy is controlled by the running effective Planck mass, linking the local process to the modified gravitational-wave luminosity distance. Finally, we extend this shear-excitation mechanism to nonminimally coupled scalars, metric $f(R)$ gravity, and viable luminal Horndeski theories, and identify the condition required for the same interpretation in more general tensor sectors.
Comments13 pages
