$f(Q,L_m)$ gravity, and its cosmological implications

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Hauptverfasser: Hazarika, Ayush, Arora, Simran, Sahoo, P. K., Harko, Tiberiu
Format: Preprint
Veröffentlicht: 2024
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author Hazarika, Ayush
Arora, Simran
Sahoo, P. K.
Harko, Tiberiu
author_facet Hazarika, Ayush
Arora, Simran
Sahoo, P. K.
Harko, Tiberiu
contents Symmetric teleparallel gravity and its $f(Q)$ extensions have emerged as promising alternatives to General Relativity (GR), yet the role of explicit geometry-matter couplings remains largely unexplored. In this work, we address this gap by proposing a generalized $f(Q,\mathcal{L}_m)$ theory, where the gravitational Lagrangian density depends on both the non-metricity scalar $Q$ and the matter Lagrangian $\mathcal{L}_m$. This formulation naturally includes Coincident GR and the Symmetric Teleparallel Equivalent of GR as special cases. Working in the metric formalism, we derive the corresponding field equations, which generalize those of the standard $f(Q)$ gravity, and obtain the modified Klein-Gordon equation for scenarios involving scalar fields. The cosmological implications of the theory are explored in the context of the Friedmann-Lemaitre-Robertson-Walker (FLRW) universe. As a first step, we obtain the modified Friedmann equations for $f(Q,\mathcal{L}_m)$ gravity in full generality. We then investigate specific cosmological models arising from both linear and non-linear choices of $f(Q,\mathcal{L}_m)$, performing detailed comparisons with the standard $Λ$CDM scenario and examining their observational consequences.
format Preprint
id arxiv_https___arxiv_org_abs_2407_00989
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle $f(Q,L_m)$ gravity, and its cosmological implications
Hazarika, Ayush
Arora, Simran
Sahoo, P. K.
Harko, Tiberiu
General Relativity and Quantum Cosmology
High Energy Physics - Theory
Symmetric teleparallel gravity and its $f(Q)$ extensions have emerged as promising alternatives to General Relativity (GR), yet the role of explicit geometry-matter couplings remains largely unexplored. In this work, we address this gap by proposing a generalized $f(Q,\mathcal{L}_m)$ theory, where the gravitational Lagrangian density depends on both the non-metricity scalar $Q$ and the matter Lagrangian $\mathcal{L}_m$. This formulation naturally includes Coincident GR and the Symmetric Teleparallel Equivalent of GR as special cases. Working in the metric formalism, we derive the corresponding field equations, which generalize those of the standard $f(Q)$ gravity, and obtain the modified Klein-Gordon equation for scenarios involving scalar fields. The cosmological implications of the theory are explored in the context of the Friedmann-Lemaitre-Robertson-Walker (FLRW) universe. As a first step, we obtain the modified Friedmann equations for $f(Q,\mathcal{L}_m)$ gravity in full generality. We then investigate specific cosmological models arising from both linear and non-linear choices of $f(Q,\mathcal{L}_m)$, performing detailed comparisons with the standard $Λ$CDM scenario and examining their observational consequences.
title $f(Q,L_m)$ gravity, and its cosmological implications
topic General Relativity and Quantum Cosmology
High Energy Physics - Theory
url https://arxiv.org/abs/2407.00989