A novel teleparallel dark energy model

Although equivalent to general relativity, teleparallel gravity is conceptually speaking a completely different theory. In this theory, the gravitational field is described by torsion, not by curvature. By working in this context, a new model is proposed in which the four-derivative of a canonical scalar field representing dark energy is nonminimally coupled to the "vector torsion". This type of coupling is motivated by the fact that a scalar field couples to torsion through its four-derivative, which is consistent with local spacetime kinematics regulated by the de Sitter group $SO(1,4)$. It is found that the current state of accelerated expansion of the Universe corresponds to a late-time attractor that can be (i) a dark-energy-dominated de Sitter solution ($\omega_{\phi}=-1$), (ii) a quintessence-type solution with $\omega_{\phi}\geq-1$, or (iii) a phantom-type $\omega_{\phi}<-1$ dark energy.