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arXiv 2101.00641hep-thgr-qchep-ph
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简并Horava引力

Degenerate Horava gravity

Enrico Barausse, Marco Crisostomi, Stefano Liberati, Lotte ter Haar

摘要:

Horava引力通过引入一个动态类时标量场(khronon)打破了洛伦兹对称性,它可以被用作一个优选的时间坐标(从而选择一个优选的时空叶理)。采用khronon作为时间坐标,该理论仅在时间重参数化和空间同态下是不变的。在红外线极限,这个理论有时被称为khronometric理论。在这里,我们明确地构建了一个广义的khronometric理论,它避免了Ostrogradski模式的传播作为一个合适的简并条件的结果(虽然后者的稳定性下的辐射校正仍然是一个悬而未决的问题)。虽然这一新理论没有广义相对论的极限,也没有产生大尺度上的弗里德曼-罗伯逊-沃克式宇宙学,但只要适当选择其耦合常数,它仍然通过了地球和太阳系的局部检验,以及引力波检验。我们还评论了这个理论作为量子引力的玩具模型的可能有用性,因为它可以在紫外线中完成,成为一个"退化的Horava引力"理论,可以微扰重整化,而不施加任何投射条件。

英文摘要:

Horava gravity breaks Lorentz symmetry by introducing a dynamical timelike scalar field (the khronon), which can be used as a preferred time coordinate (thus selecting a preferred space-time foliation). Adopting the khronon as the time coordinate, the theory is invariant only under time reparametrizations and spatial diffeomorphisms. In the infrared limit, this theory is sometimes referred to as khronometric theory. Here, we explicitly construct a generalization of khronometric theory, which avoids the propagation of Ostrogradski modes as a result of a suitable degeneracy condition (although stability of the latter under radiative corrections remains an open question). While this new theory does not have a general-relativistic limit and does not yield a Friedmann-Robertson-Walker-like cosmology on large scales, it still passes, for suitable choices of its coupling constants, local tests on Earth and in the solar system, as well as gravitational-wave tests. We also comment on the possible usefulness of this theory as a toy model of quantum gravity, as it could be completed in the ultraviolet into a 'degenerate Horava gravity' theory that could be perturbatively renormalizable without imposing any projectability condition.

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