$f(Q,T)$ gravity, its covariant formulation, energy conservation and phase-space analysis
| Autor: | Loo, Tee-How, Solanki, Raja, De, Avik, Sahoo, P. K. |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | Eur. Phys. J. C 83(3) (2023) 261 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1140/epjc/s10052-023-11391-4 |
| Popis: | In the present article we analyze the matter-geometry 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-Lema\^{i}tre-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 $\beta \neq 0$ 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 $\alpha \neq 0$ represents an accelerated de-Sitter epoch for the constraints $\beta < -1$ or $ \beta \geq 0$. Comment: EPJC accepted version |
| Databáze: | arXiv |
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