Late-time cosmology in the extended cuscuton theory is studied, in which gravity is modified while one still has no extra dynamical degrees of freedom other than two tensor modes. We present a simple example admitting analytic solutions for the cosmological background evolution that mimics $\Lambda$CDM cosmology. We argue that the extended cuscuton as dark energy can be constrained, like usual scalar-tensor theories, by the growth history of matter density perturbations and the time variation of Newton's constant.

中文翻译：

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作为暗能量的扩展cuscuton

研究了扩展 cuscuton 理论中的晚期宇宙学，其中重力被修改，而除了两个张量模式外，仍然没有额外的动力学自由度。我们提出了一个简单的例子，它承认模拟 $\Lambda$CDM 宇宙学的宇宙学背景演化的解析解。我们认为，作为暗能量的扩展 cuscuton 可以像通常的标量张量理论一样受到物质密度扰动的增长历史和牛顿常数的时间变化的约束。