Modified gravity and cosmic acceleration: now and in the early universe

0567549 - FZÚ 2023 CZ eng D - Thesis
Jiroušek, Pavel
Modified gravity and cosmic acceleration: now and in the early universe.
Univerzita Karlova, Matematicko-fyzikální fakulta. Defended: Univerzita Karlova, Matematicko-fyzikální fakulta Praha. 2022. - Praha, 2022. 65 s.
Institutional support: RVO:68378271
Keywords : inflation * dark energy * cosmic acceleration * gravity modifications
OECD category: Particles and field physics

We review our previous works which explored the problems of dark energy and cos- mological constant problem in the context of modified gravity. In the first part, we present extensions of mimetic dark matter. The latter is a Weyl-invariant scalar-tensor theory able to describe dark matter on cosmological scales. In our works we have extended the mimetic construction to vector fields and Yang-Mills gauge fields. The resulting theories provided a novel Weyl-invariant and higher derivative formulations of unimodular gravity. We also introduced a mixture of this mimetic dark energy with mimetic dark matter and showed that it results in k-essence like scalar theory. In the second part we reviewed a minimal modification of Einstein equations, in which their trace part is made trivial.
Permanent Link: https://hdl.handle.net/11104/0338825