Mixed Galileons and spherically symmetric solutions
Mixed Galileons and spherically symmetric solutions
复制标题
混合伽利略和球对称解
DOI：
10.1088/0264-9381/30/18/184003
复制
发表时间：
2013
影响因子：
3.5
通讯作者：
A. Tolley
中科院分区：
文献类型：
--
作者：
L. Berezhiani;G. Chkareuli;C. Rham;G. Gabadadze;A. Tolley
先前发现，在由大质量引力产生的标量-张量理论的某个参数子空间中，由静态球对称源创建的唯一稳定场配置是具有宇宙学渐进性的场配置。此外，这些背景在空间中的任何地方都被证明是亚光速的。与普遍认为这些理论在静态源附近必然是超光速的观点相反。在这项工作中，我们通过将其扩展到覆盖这些标量张量理论的整个参数空间来完成该分析。我们发现稳定性论证使得渐近平坦的背景无法实现，再次迫使宇宙论渐近论。在无压力源的情况下，这些背景是稳定的。然而，当存在大于临界密度的正压时，它们会变得不稳定。即使在标量模式与源解耦的自加速背景上，在源占据的区域中，它也会获得椭圆运动方程。因此，我们得出的结论是，通过太阳系测量，唯一不排除的参数空间是 Berezhiani 等人 (2013 arXiv:1302.0549) 中考虑的参数空间，即标量和张量模式可以通过局部变换对角化的参数空间。我们还重新研究了一般伽利略理论中微扰理论失效的规模。我们表明，尽管在特殊的球对称情况下发生了抵消，但 Vainshtein 机制成功地将强耦合尺度纠正为较小的尺度，就像三次伽利略一样。我们强调，即使这些测试是在微扰理论失效的尺度上进行的，这些也不能被解释为引力子质量的下限。
It was previously found that in a certain parameter subspace of scalar–tensor theories emerging from massive gravity, the only stable field configuration created by static spherically symmetric sources was one with cosmological asymptotics. Moreover, these backgrounds were shown to be subluminal everywhere in the space; in contrast to the common belief that these theories are necessarily superluminal in the vicinity of a static source. In this work, we complete that analysis by extending it to cover the whole parameter space of these scalar–tensor theories. We find that the stability argument renders the asymptotically flat backgrounds unrealizable, forcing once again for cosmological asymptotics. In the case of pressure-less sources, these backgrounds are stable. However, they get destabilized in the presence of positive pressure, larger than a critical density. Even on the self-accelerated background, on which the scalar mode decouples from sources, in the region occupied by the source it acquires an elliptic equation of motion. Therefore, we conclude that the only parameter space which is not ruled out, by solar system measurements, is the one considered in Berezhiani et al (2013 arXiv:1302.0549), namely the one for which the scalar and tensor modes can be diagonalized via local transformations. We also reinvestigate the scale at which a perturbation theory breaks down in a general Galileon theory. We show that the Vainshtein mechanism successfully redresses the strong-coupling scale to a small one, just like in the cubic Galileon, despite the cancellations occurring in the special spherically symmetric case. We emphasize that even if these tests were performed at scales at which the perturbation theory broke down, these could not be interpreted as a lower bound for the graviton mass.