Scalar perturbation and density contrast evolution in $f(Q,C)$ gravity

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Main Authors: Subramaniam, Ganesh, De, Avik, Loo, Tee-How, Goh, Yong Kheng
Format: Preprint
Published: 2024
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author Subramaniam, Ganesh
De, Avik
Loo, Tee-How
Goh, Yong Kheng
author_facet Subramaniam, Ganesh
De, Avik
Loo, Tee-How
Goh, Yong Kheng
contents The symmetric teleparallel theory offers an alternative gravitational formulation which can elucidate events in the early and late universe without requiring the physical existence of dark matter or dark energy. In this formalism, $f(Q, C)$ gravity has been recently introduced by incorporating the boundary term $C$ with the non-metricity scalar $Q$. In this paper, we develop the theory of cosmological scalar perturbation for $f(Q, C)$ gravity, and retrieve that of $f(\mathring{R})$ and $f(Q)$ gravity from our result. The analysis assumes a model-independent approach within these theories that adheres to the conventional continuity equation at the background level. We derive the density contrast equation by employing some standard cosmological approximations, where the $f(Q,C)$ theory is encoded in the effective Newtonian constant $G_{eff}$. Finally, we derive the evolution equation of density growth $f_g$.
format Preprint
id arxiv_https___arxiv_org_abs_2412_05382
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Scalar perturbation and density contrast evolution in $f(Q,C)$ gravity
Subramaniam, Ganesh
De, Avik
Loo, Tee-How
Goh, Yong Kheng
General Relativity and Quantum Cosmology
The symmetric teleparallel theory offers an alternative gravitational formulation which can elucidate events in the early and late universe without requiring the physical existence of dark matter or dark energy. In this formalism, $f(Q, C)$ gravity has been recently introduced by incorporating the boundary term $C$ with the non-metricity scalar $Q$. In this paper, we develop the theory of cosmological scalar perturbation for $f(Q, C)$ gravity, and retrieve that of $f(\mathring{R})$ and $f(Q)$ gravity from our result. The analysis assumes a model-independent approach within these theories that adheres to the conventional continuity equation at the background level. We derive the density contrast equation by employing some standard cosmological approximations, where the $f(Q,C)$ theory is encoded in the effective Newtonian constant $G_{eff}$. Finally, we derive the evolution equation of density growth $f_g$.
title Scalar perturbation and density contrast evolution in $f(Q,C)$ gravity
topic General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2412.05382