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Participant |
Saridakis, Emmanuel | |||||||
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Institution |
Baylor U. - Baylor University - Waco - TX - USA | |||||||
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Session |
AT1 |
Accepted |
Yes |
Order |
8 |
Time |
17:20 | 25' |
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Talk |
Oral abstract |
Title |
Teleparallel, F(T) and Other Torsional Modified Gravities, and Their Cosmological Applications | |||||
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Abstract |
Torsion has been proved to be crucial in gauging gravity, which is in turn a necessary step towards its quantization. On the other hand, almost all the efforts in modifying gravity has been performed in the usual curvature-based framework. We investigate the case where one modifies gravity based on its torsional-teleparallel formulation, namely the f(T) gravity paradigm, and its cosmological applications. Moreover, we analyze the perturbations of the theory examining the growth history, we construct a cosmological bounce, and we use solar system and cosmological observations in order to impose constraints on the f(T) forms. Additionally, we analyze the charged black hole solutions of the theory, performing a comparison between f(R) and f(T) modifications. Finally, we study the case where T is nonminimally coupled to a scalar field, as well as other extensions of the theory, using higher-order torsion invariants, or torsion-matter couplings. |
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Pdf file |
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Session |
DE1 |
Accepted |
Yes |
Order |
3 |
Time |
15:15 | 15' |
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Talk |
Oral abstract |
Title |
f(R) nonlinear massive gravity and cosmology | |||||
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Abstract |
Massive gravity is the most reasonable (although not the simplest) extension of General Relativity that one can think of. Apart from theoretical interest, one has a strong cosmological motivation too: massive gravity implies that gravity becomes weaker and weaker at large distances and thus one could hope to explain the universe acceleration. Simple models suffer from the problems of van Dam-Veltman-Zakharov discontinuity and Boulware-Deser ghosts. Although these can be cured through the recently constructed de Rham-Gabadadze-Tolley nonlinear massive gravity, unfortunately this new theory does not exhibit cosmological behaviour in agreement with observations. Thus, suitably extensions are necessary, such as f(R) nonlinear massive gravity. We construct it and we investigate the cosmological and phenomenological implications of such a theory, obtaining an effective dark energy sector that drives late time acceleration. |
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Pdf file |
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