Degenerate higher order scalar-tensor theories beyond Horndeski up to cubic order
Degenerate higher order scalar-tensor theories beyond Horndeski up to cubic order
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DOI：
10.1007/jhep12(2016)100
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发表时间：
2016-12-20
影响因子：
5.4
通讯作者：
Tasinato, G.
中科院分区：
文献类型：
--
作者：
Ben Achour, J.;Crisostomi, M.;Tasinato, G.
我们给出了所有标量场二阶导数为三次的标量张量拉格朗日量，它们是简并的，因此避免了Ostrogradsky不稳定性。由于存在约束，尽管它们具有高阶运动方程，但它们的传播自由度不超过三个。我们还确定了以前确定的二次退化拉格朗日和新建立的三次退化拉格朗日的可行组合。最后，我们研究了新理论是否与已知的标量张量理论（如Horndeski和Horndeski以外的）通过共形或非形变换相联系。
We present all scalar-tensor Lagrangians that are cubic in second derivatives of a scalar field, and that are degenerate, hence avoiding Ostrogradsky instabilities. Thanks to the existence of constraints, they propagate no more than three degrees of freedom, despite having higher order equations of motion. We also determine the viable combinations of previously identified quadratic degenerate Lagrangians and the newly established cubic ones. Finally, we study whether the new theories are connected to known scalartensor theories such as Horndeski and beyond Horndeski, through conformal or disformal transformations.