On $f(R)$ gravity in scalar-tensor theories
| Autor: | Ntahompagaze, Joseph, Abebe, Amare, Mbonye, Manasse |
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| Rok vydání: | 2017 |
| Předmět: | |
| Zdroj: | IJGMMP Vol. 14, No. 7 (2017) 1750107 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1142/S0219887817501079 |
| Popis: | We study $f(R)$ gravity models in the language of scalar-tensor theories. The correspondence between $f(R)$ gravity and scalar-tensor theories is revisited since $f(R)$ gravity is a subclass of Brans-Dicke models, with a vanishing coupling constant ($\omega=0$). In this treatment, four $f(R)$ toy models are used to analyze the early-universe cosmology, when the scalar field $\phi$ dominates over standard matter. We have obtained solutions to the Klein-Gordon equation for those models. It is found that for the first model $\left(f(R)=\beta R^{n}\right)$, as time increases the scalar field decreases and decays asymptotically. For the second model $\left(f(R)=\alpha R+\beta R^{n}\right)$ it was found that the function $\phi(t)$ crosses the $t$-axis at different values for different values of $\beta$. For the third model $\left(f(R)=R-\frac{\nu^{4}}{R}\right)$, when the value of $\nu$ is small the potential $V(\phi)$ behaves like the standard inflationary potential. For the fourth model $\left(f(R)=R-(1-m)\nu^{2}\Big(\frac{R}{\nu^{2}}\Big)^{m}-2\Lambda\right)$, we show that there is a transition between $1.5 Comment: 27 pages, 7 figures, Published in IJGMMP |
| Databáze: | arXiv |
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