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arXiv · 1405.0519

$f(T,\mathcal{T})$ gravity and cosmology

Tiberiu Harko·Francisco S. N. Lobo·G. Otalora·Emmanuel N. Saridakis
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Abstract

We present an extension of $f(T)$ gravity, allowing for a general coupling of the torsion scalar $T$ with the trace of the matter energy-momentum tensor $\mathcal{T}$. The resulting $f(T,\mathcal{T})$ theory is a new modified gravity, since it is different from all the existing torsion or curvature based constructions. Applied to a cosmological framework, it leads to interesting phenomenology. In particular, one can obtain a unified description of the initial inflationary phase, the subsequent non-accelerating, matter-dominated expansion, and then the transition to a late-time accelerating phase. Additionally, the effective dark energy sector can be quintessence or phantom-like, or exhibit the phantom-divide crossing during the evolution. Moreover, in the far future the universe results either to a de Sitter exponential expansion, or to eternal power-law accelerated expansions. Finally, a detailed study of the scalar perturbations at the linear level reveals that $f(T,\mathcal{T})$ cosmology can be free of ghosts and instabilities for a wide class of ansatzes and model parameters.

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Tiberiu Harko, Francisco S. N. Lobo, G. Otalora, Emmanuel N. Saridakis. 2014-12-11. $f(T,\mathcal{T})$ gravity and cosmology. https://doi.org/10.1088/1475-7516%2F2014%2F12%2F021

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