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Boosting Monte Carlo sampling with a non-Gaussian fit
Adriŗ Gůmez-Valent
Tue, 19 Jan 2021, 15:15

Weakening gravity for dark matter in a type-II minimally modified gravity

Antonio De Felice , Yukawa Institute for Theoretical Physics
I 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_{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 (\Lambda CCDM), as the cosmological constant \Lambda in the standard \Lambda CDM is replaced by a function V(\phi) of an auxiliary field \phi and the CDM is minimally coupled to the metric in a canonically transformed frame.
Kosmologie und Elementarteilchenphysik
27 Nov 2020, 11:00
Institut für Theoretische Physik, Online;[NOTE UNUSAL DAY AND TIME]

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