New class of consistent scalar-tensor theories.
New class of consistent scalar-tensor theories.
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DOI：
10.1103/physrevlett.114.211101
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发表时间：
2014-04
影响因子：
8.6
通讯作者：
J'erome Gleyzes;D. Langlois;F. Piazza;F. Vernizzi
中科院分区：
文献类型：
--
作者：
J'erome Gleyzes;D. Langlois;F. Piazza;F. Vernizzi
我们引入一类新的标量张量引力理论，扩展Horndeski，或“广义Galileon”模型。尽管拥有高阶导数的运动方程，我们表明，真正的传播自由度服从行为良好的二阶方程，因此不受Ostrogradski不稳定性，与标准的知识。值得注意的是，协变版本的原始伽利略拉格朗日-通过直接替换衍生工具与协变导数-属于这一类的理论。Horndeski理论的这些扩展展示了一个不寻常的，有趣的现象：标量自由度影响物质的声速，即使后者与引力的耦合最小。
We introduce a new class of scalar-tensor theories of gravity that extend Horndeski, or "generalized Galileon," models. Despite possessing equations of motion of higher order in derivatives, we show that the true propagating degrees of freedom obey well-behaved second-order equations and are thus free from Ostrogradski instabilities, in contrast to standard lore. Remarkably, the covariant versions of the original Galileon Lagrangians-obtained by direct replacement of derivatives with covariant derivatives-belong to this class of theories. These extensions of Horndeski theories exhibit an uncommon, interesting phenomenology: The scalar degree of freedom affects the speed of sound of matter, even when the latter is minimally coupled to gravity.