论文标题
II型最小修饰的重力中暗物质的重力弱
Weakening gravity for dark matter in a type-II minimally modified gravity
论文作者
论文摘要
我们提出了一个新的宇宙学框架，在这种宇宙学框架中，引力的强度在晚期对暗物质作用可能比在标准物质领域的弱点弱，而不会引入额外的引力自由度。该框架将深色物质整合到II型最小修饰的重力中，该重力最近被提议作为暗能量模仿。使这样一个框架成为可能的想法包括将暗物质拉格朗日耦合和宇宙学常数与规范转换的一般相对性框架（GR）耦合。在施加规范固定约束时，明确打破了时间的差异不变性，我们将重力自由度的重力自由度保持在gr中。然后，我们进行逆规范转换，将理论带回原始框架，在那里可以添加标准物质字段。该框架包含两个免费的时间功能，这些功能指定了上述规范转换的生成功能，然后将其用于实现哈勃膨胀率$ h（z）$的所需时间演变，以及对暗物质的有效重力常数$ g _ {\ rm eff}（z）$。因此，本文的目的是提供一个新的框架，以解决当今宇宙学中存在的两个难题，即$ H_0 $张力和$ S_8 $张力。 When the dark matter is cold in this framework, we dub the corresponding cosmological model the V Canonical Cold Dark Matter (VCCDM), as the cosmological constant $Λ$ in the standard $Λ$CDM is replaced by a function $V(ϕ)$ of an auxiliary field $ϕ$ and the CDM is minimally coupled to the metric in a canonically transformed frame.
We propose a new cosmological framework in which the strength of the gravitational force acted on dark matter at late time can be weaker than that on the standard matter fields without introducing extra gravitational degrees of freedom. The framework integrates dark matter into a type-II minimally modified gravity that was recently proposed as a dark energy mimicker. The idea that makes such a framework possible consists of coupling a dark matter Lagrangian and a cosmological constant to the metric in a canonically transformed frame of general relativity (GR). On imposing a gauge fixing constraint, which explicitly breaks the temporal diffeomorphism invariance, we keep the number of gravitational degrees of freedom to be two, as in GR. We then make the inverse canonical transformation to bring the theory back to the original frame, where one can add the standard matter fields. This framework contains two free functions of time which specify the generating functional of the above mentioned canonical transformation and which are then used in order to realize desired time evolutions of both the Hubble expansion rate $H(z)$ and the effective gravitational constant for dark matter $G_{\rm eff}(z)$. The aim of this paper is therefore to provide a new framework to address the two puzzles present in today's cosmology, i.e. the $H_0$ tension and the $S_8$ tension, simultaneously. When the dark matter is cold in this framework, we dub the corresponding cosmological model the V Canonical Cold Dark Matter (VCCDM), as the cosmological constant $Λ$ in the standard $Λ$CDM is replaced by a function $V(ϕ)$ of an auxiliary field $ϕ$ and the CDM is minimally coupled to the metric in a canonically transformed frame.
