Abstract
It is investigated the cosmological dynamics of scalar-torsion f(T,phi ) gravity as a dark energy model, where T is the torsion scalar of teleparallel gravity and phi is a canonical scalar field. In this context, we are concerned with the phenomenology of the class of models with non-linear coupling to gravity and exponential potential. We obtain the critical points of the autonomous system, along with the stability conditions of each one of them and their cosmological properties. Particularly, we show the existence of new attractors with accelerated expansion, as well as, new scaling solutions in which the energy density of dark energy scales as the background fluid density, thus, defining the so-called scaling radiation and scaling matter epochs. The scaling solutions are saddle points, and therefore, the system exits these solutions to the current epoch of cosmic acceleration, towards an attractor point describing the dark energy-dominated era.
Highlights
The energy density associated a e-mail: manuel.gonzalez@pucv.cl b e-mail: giovanni.otalora@pucv.cl with the cosmological constant today is to be of the order of the critical density, ρΛ ∼ 10−47 GeV4, but if we identify it with the energy density of the vacuum in quantum field theory, it should be enormously larger, about 10121 times larger than the observed value, that is, ρΛ ∼ 1074 GeV4, when the cut-off scale is chosen to be the Planck scale [6]
In the present work we have investigated the cosmological dynamics of dark energy in the context of scalar-torsion f (T, φ) gravity, where f (T, φ) is a function of the torsion scalar T, associated with the Weitzenböck connection in the
The exponential scalar potential is the usual one studied in the context of dark energy which admits scaling solutions, while the exponential coupling function of the scalar field is the simplest natural choice to be assumed with this potential [53]
Summary
The minimally and non-minimally coupled scalar field models are giving good results for mitigating the current tensions in the concordance model [56,57] It is well known gravity can be described in terms of torsion in the context of Teleparallel Gravity (TG) [58,59,60,61,62,63,64,65,66,67,68,69,70]. Page 3 of 17 480 observed, no attractor fixed point exists In this present work we investigate a class of models belonging to a more general scalar-torsion f (T, φ) gravity theories [106,107], where it is allowed a non-linear gravitational coupling between the scalar field and torsion.
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