http://arxiv.org/abs/1802.01413
In unimodular gravity the cosmological constant $\Lambda$ appears naturally as an integration constant when deriving the field equations of the theory and using the conservation of the matter components. Therefore, the unimodular approach seems to naturally alleviate some usual problems associated to $\Lambda$. A crucial aspect and matter of intense debate is the conservation of the energy momentum tensor which is usually obtained by imposing the general covariance to the matter sector. In this work, being inspired by theories {\it `a la} Rastall, we develop the unimodular type theory evading the conservation $T^{\mu\nu}_{\, ; \mu}=0$ and explore the cosmological consequences both at background and first order in scalar and tensor perturbations of this approach. Possible extensions of this approach are discussed.
M. Daouda, J. Fabris, A. Oliveira, et. al.
Tue, 6 Feb 18
10/62
Comments: 12 pages, 4 figures
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