Bigravity from gradient expansion
Bigravity from gradient expansion
复制标题
梯度膨胀产生的重引力
DOI：
10.1088/1475-7516/2016/05/011
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发表时间：
2016
影响因子：
6.4
通讯作者：
Yasuho Yamashita and Takahiro Tanaka
中科院分区：
文献类型：
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作者：
山元一広;都丸隆行 他;三部 勉;Yasuho Yamashita and Takahiro Tanaka
我们讨论如何从膜世界设置中导出与单个标量场相结合的无鬼重引力。我们考虑没有放射性稳定的 DGP 双膜模型。针对给定的边界度量求解批量配置，并将其代回动作中以获得有效的四维动作。为了获得无重影的重重力，我们考虑梯度扩展，其中膜分离应该足够小，以便两个边界度量几乎相同。所获得的有效理论被证明是没有鬼魂的，正如预期的那样，然而，即使我们不使用线性扰动的近似，两个引力子之间的相互作用在梯度展开的前导阶处呈现Fierz-Pauli形式。我们还发现，在四维有效理论中，放射性仍然是一个标量场，但它与度量的耦合是重要的。
We discuss how the ghost-free bigravity coupled with a single scalar field can be derived from a braneworld setup. We consider DGP two-brane model without radion stabilization. The bulk configuration is solved for given boundary metrics, and it is substituted back into the action to obtain the effective four-dimensional action. In order to obtain the ghost-free bigravity, we consider the gradient expansion in which the brane separation is supposed to be sufficiently small so that two boundary metrics are almost identical. The obtained effective theory is shown to be ghost free as expected, however, the interaction between two gravitons takes the Fierz-Pauli form at the leading order of the gradient expansion, even though we do not use the approximation of linear perturbation. We also find that the radion remains as a scalar field in the four-dimensional effective theory, but its coupling to the metrics is non-trivial.