| 1. |
- Golovnev, Alexey, et al.
(author)
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Cosmological perturbations in modified teleparallel gravity models
- 2018
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In: Journal of Cosmology and Astroparticle Physics. - : IOP PUBLISHING LTD. - 1475-7516. ; :11
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Journal article (peer-reviewed)abstract
- Cosmological perturbations are considered in f (T) and in scalar-torsion f (phi) T teleparallel models of gravity. Full sets of linear perturbation equations are accurately derived and analysed at the relevant limits. Interesting features of generalisations to other teleparallel models, spatially curved backgrounds, and rotated tetrads are pointed out.
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| 2. |
- Golovnev, Alexey, et al.
(author)
-
Effectively nonlocal metric-affine gravity
- 2016
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In: PHYSICAL REVIEW D. - : American Physical Society. - 2470-0010. ; 93:6
-
Journal article (peer-reviewed)abstract
- In metric-affine theories of gravity such as the C-theories, the spacetime connection is associated to a metric that is nontrivially related to the physical metric. In this article, such theories are rewritten in terms of a single metric, and it is shown that they can be recast as effectively nonlocal gravity. With some assumptions, known ghost-free theories with nonsingular and cosmologically interesting properties may be recovered. Relations between different formulations are analyzed at both perturbative and nonperturbative levels, taking carefully into account subtleties with boundary conditions in the presence of integral operators in the action, and equivalences between theories related by nonlocal redefinitions of the fields are verified at the level of equations of motion. This suggests a possible geometrical interpretation of nonlocal gravity as an emergent property of non-Riemannian spacetime structure.
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| 3. |
- Golovnev, Alexey, et al.
(author)
-
On the covariance of teleparallel gravity theories
- 2017
-
In: Classical and quantum gravity. - : Institute of Physics Publishing (IOPP). - 0264-9381 .- 1361-6382. ; 34:14
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Journal article (peer-reviewed)abstract
- The basics of teleparallel gravity and its extensions are reviewed with particular emphasis on the problem of the Lorentz-breaking choice of connection in pure-tetrad versions of the theories. Various possible ways to covariantise such models are discussed. A by-product is a new form of f (T) field equations.
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