f (Q, T) gravity, its covariant formulation, energy conservation and phase-space analysis
Document Type
Article
Publication Date
3-1-2023
Abstract
In the present article we analyze the mattergeometry coupled f (Q, T) theory of gravity. We offer the fully covariant formulation of the theory, with which we construct the correct energy balance equation and employ it to conduct a dynamical system analysis in a spatially flat Friedmann-Lemaitre-Robertson-Walker spacetime. We consider three different functional forms of the f (Q, T) function, specifically, f (Q, T) = alpha Q + beta T, f ( Q, T) = alpha Q + beta T-2, and f (Q, T) = Q + alpha Q(2) + beta T. We attempt to investigate the physical capabilities of these models to describe various cosmological epochs. We calculate Friedmann-like equations in each case and introduce some phase space variables to simplify the equations in more concise forms. We observe that the linear model f (Q, T) = alpha Q + beta T with beta = 0 is completely equivalent to the GR case without cosmological constant Lambda. Further, we find that the model f (Q, T) = alpha Q + beta T-2 with beta not equal 0 successfully depicts the observed transition from decelerated phase to an accelerated phase of the universe. Lastly, we find that the model f (Q, T) = Q + alpha Q(2) + beta T with a not equal 0 represents an accelerated de-Sitter epoch for the constraints beta < -1 or beta = 0.
Keywords
Theory of gravity, Cosmological epochs
Divisions
MathematicalSciences
Funders
Ministry of Higher Education (MoHE), through the Fundamental Research Grant Scheme [Grant No: FRGS/1/2021/STG06/UTAR/02/1],University Grants Commission, India [Grant No: 191620096030],Science and Engineering Research Board, Department of Science and Technology, Government of India [Grant No: CRG/2022/001847]
Publication Title
European Physical Journal C
Volume
83
Issue
3
Publisher
Springer
Publisher Location
ONE NEW YORK PLAZA, SUITE 4600, NEW YORK, NY, UNITED STATES