Cosmology in R2-gravity: Effects of a higher derivative scalar condensate background

Article Type

Research Article

Publication Title

Journal of High Energy Astrophysics

Abstract

A well known extension of Einstein's General Relativity is the addition of an R2-term, which is free of ghost excitations and in the linearized framework, reduces to the conventional spin-2 graviton and an additional higher derivative scalar. According to Chakraborty and Ghosh (2022), 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-Lemaître-Robertson-Walker (FLRW) cosmology in this background. The effect of the R2-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).

First Page

231

Last Page

238

DOI

10.1016/j.jheap.2024.07.011

Publication Date

8-1-2024

Comments

Open Access; Green Open Access

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