Cosmology in $R^2$-gravity: Effects of a Higher Derivative Scalar Condensate Background
| Autor: | Das, Raj Kumar, Mondal, Aurindam, Ghosh, Subir, Pan, Supriya |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | JHEAp 43 (2024) 231-238 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1016/j.jheap.2024.07.011 |
| Popis: | A well known extension of Einstein General Relativity is the addition of an $R^2$-term, which is free of ghost excitations and in the linearized framework, reduces Einstein General Relativity and an additional higher derivative scalar. According to \cite{Chakraborty:2020ktp}, the above scalar sector can sustain a Time Crystal-like minimum energy state, with non-trivial time dependence. Exploiting previous result that the scalar can sustain modes with periodic time dependence in its lowest energy, we consider this condensate as a source and study the Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW) cosmology in this background. The effect of the $R^2$-term is interpreted as a back reaction. A remarkable consequence of the condensate is that, irrespective of open or close geometry of the Universe, for an appropriate choice of parameter window, the condensate can induce a decelerating phase before the accelerated expansion starts and again, in some cases, it can help to avoid the singularity in the deceleration parameter (that is present in conventional FLRW Cosmology). Comment: 10 pages including references, 4 compound figures; published version in JHEAp |
| Databáze: | arXiv |
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