http://arxiv.org/abs/1802.07981
A unification of dark matter and dark energy based on a dynamical space time theories is explored. By introducing a dynamical space time vector field $\chi_\mu$, a conservation of an energy momentum tensor $T^{\mu\nu}{(\chi)}$ is implemented. This Lagrangian formulation generalize a “Unified dark energy and dark matter from a scalar field different from quintessence” [Phys.RevD 81, 043520 (2010)] which did not considered a Lagrangian formulation. This generalization allows for the solutions found previously, but also not singular bounce solutions that rapidly approach a $\Lambda$CDM behavior. The time component of the dynamical space time vector exactly coincides with the cosmic time for the solutions that are exactly $\Lambda$CDM and suffers a slight shift with respect to the cosmic time in the region close to the bounce for the bouncing non singular solutions. In addition we introduced some exponential potential which could enter into $T^{\mu\nu}{(\chi)}$ or coupled directly to $\sqrt{-g}$ which gives an interaction between DE and DM and gives the possibility of explaining the coincidence problem.
D. Benisty and E. Guendelman
Fri, 23 Feb 18
25/64
Comments: 7 pages