论文标题
广义的单型重力作为k词的一种形式
Generalized unimodular gravity as a form of k-essence
论文作者
论文摘要
我们考虑了一般相对论的修改，其特征在于对度量系数的特殊非交流限制，该限制有效地产生了爱因斯坦方程中的完美流体物质应力张量。这种修改的重力模型包括最近建议的广义单型重力（GUMG）理论及其最简单的版本 - 单型重力（UMG）。我们通过引入四个stueckelberg田地来使这些重力模型协变，并表明，在普遍的单模型重力的情况下，这些场中的三个磁场都动态脱料。这意味着，具有特定的Lagrangian可以从GUMG理论的参数中重建的特定的Lagrangian动态地等同于K-效率理论的协变形式。我们提供了可以明确进行此类重建的示例，并简要讨论与Gumg之外的理论有关，这与自我修复的媒体模型有关。另外，我们将Gumg K膨胀与动态惰性K- essence领域的Cuscuton模型进行了比较，并讨论了来自有效田间理论的GUMG的动机。
We consider modifications of general relativity characterized by a special noncovariant constraint on metric coefficients, which effectively generates a perfect-fluid type of matter stress tensor in Einstein equations. Such class of modified gravity models includes recently suggested generalized unimodular gravity (GUMG) theory and its simplest version -- unimodular gravity (UMG). We make these gravity models covariant by introducing four Stueckelberg fields and show that in the case of generalized unimodular gravity three out of these fields dynamically decouple. This means that the covariant form of generalized unimodular gravity is dynamically equivalent to k-essence theory with a specific Lagrangian which can be reconstructed from the parameters of GUMG theory. We provide the examples, where such reconstruction can be done explicitly, and briefly discuss theories beyond GUMG, related to self-gravitating media models. Also we compare GUMG k-inflation with cuscuton models of dynamically inert k-essence field and discuss motivation for GUMG coming from effective field theory.
