Zobrazeno 1 - 10
of 36
pro vyhledávání: '"Daouda, Mahamadou"'
Unimodular gravity (UG) is considered, under many aspects, equivalent to General Relativity (GR), even if the theory is invariant under a more restricted diffeomorphic class of transformations. We discuss the conditions for the equivalence between th
Externí odkaz:
http://arxiv.org/abs/2310.19037
Autor:
Almeida, Alexandre M. R., Fabris, Júlio C., Daouda, Mahamadou Hamani, Kerner, Richard, Velten, Hermano, Hipólito-Ricaldi, Wiliam S.
We propose a unimodular version of the Brans-Dicke theory designed with a constrained Lagrangian formulation. The resulting field equations are traceless. The vacuum solutions in the cosmological background reproduce the corresponding solutions of th
Externí odkaz:
http://arxiv.org/abs/2207.13195
Unimodular gravity is characterized by an extra condition with respect to General Relativity: the determinant of the metric is constant. This extra condition leads to a more restricted class of invariance by coordinate transformation. Even though, if
Externí odkaz:
http://arxiv.org/abs/2112.06663
In this work we review the issue of imposing the conservation of the energy-momentum tensor as a necessary condition to recover the equivalence between the unimodular gravity and General Relativity (GR) equipped with a cosmological constant. This pro
Externí odkaz:
http://arxiv.org/abs/2112.06644
Autor:
Fabris, Júlio César1,2 (AUTHOR) julio.fabris@cosmo-ufes.org, Daouda, Mahamadou Hamani3 (AUTHOR) daoudah77@gmail.com, Velten, Hermano4 (AUTHOR) hermano.velten@ufop.edu.br
Publikováno v:
Universe (2218-1997). Dec2023, Vol. 9 Issue 12, p515. 15p.
Publikováno v:
International Journal of Modern Physics D Vol. 28, No. 15, 1950175 (2019)
Extensions of the gravity theory in order to obtain traceless field equations have been widely considered in the literature. The leading example of such class of theories is the unimodular gravity, but there are other possibilities like the mimetic g
Externí odkaz:
http://arxiv.org/abs/1802.01413
Autor:
Caramês, Thiago R. P., Daouda, Mahamadou H., Fabris, Júlio C., de Oliveira, Adriano M., Piattella, Oliver F., Strokov, Vladimir
Publikováno v:
Eur. Phys. J. C74 (2014) 3145
We formulate a theory combining the principles of a scalar-tensor gravity and Rastall's proposal of a violation of the usual conservation laws. We obtain a scalar-tensor theory with two parameters $\omega$ and $\lambda$, the latter quantifying the vi
Externí odkaz:
http://arxiv.org/abs/1409.2322
Publikováno v:
AIP Conf.Proc. 1471 (2012) 57-60
We review the difficulties of the generalized Chaplygin gas model to fit observational data, due to the tension between background and perturbative tests. We argue that such issues may be circumvented by means of a self-interacting scalar field repre
Externí odkaz:
http://arxiv.org/abs/1204.2298
Autor:
Batista, Carlos E. M., Daouda, Mahamadou H., Fabris, Júlio C., Piattella, Oliver F., Rodrigues, Davi C.
Publikováno v:
Phys. Rev. D 85, 084008 (2012)
Rastall's theory is based on the non-conservation of the energy-momentum tensor. We show that, in this theory, if we introduce a two-fluid model, one component representing vacuum energy whereas the other pressureless matter (e.g. baryons plus cold d
Externí odkaz:
http://arxiv.org/abs/1112.4141
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