Towards realisticf(T)models with nonminimal torsion-matter coupling extension

Abstract

Using the observation data of SNeIa, CMB and BAO, we establish two concrete f (T ) models with nonminimal torsion-matter coupling extension. We study in detail the cosmological implication of our models and find they are successful in describing the observation of the Universe, its large scale structure and evolution. In other words, these models do not change the successful aspects of ΛCDM scenario under the error band of fitting values as describing the evolution history of the Universe including radiation-dominated era, matter-dominated era and the present accelerating expansion. Meanwhile, the significant advantage of these models is that they could avoid the cosmological constant problem of ΛCDM. A joint analysis is performed by using the data of CMB+BAO+JLA, which leads to Ωm0 = 0.255 ± 0.010, Ω b0 h 2 = 0.0221 ± 0.0003 and H0 = 68.54 ± 1.27 for model I and Ωm0 = 0.306 ± 0.010, Ω b0 h 2 = 0.0225 ± 0.0003 and H0 = 60.97 ± 0.44 for model II at 1σ confidence level. The evolution of the decelaration parameter q(a) and the effective equation of state wDE(a) are displayed. Furthermore, The resulted age of the Universe from our models is consistent with the ages of the oldest globular clusters. As for the fate of the Universe, model I results in a de Sitter accelerating phase while model II appears a power-law one, even though wDE0 < −1 makes model I look like a phantom at present time.PACS numbers: 04.50. Kd, 95.36.+x arXiv:1511.07935v1 [gr-qc]

Solar system tests for realistic f(T) models with non-minimal torsion–matter coupling

“…[31], in cosmological cases, i.e. with the Friedmann-Lemaître-Robertson-Walker (FLRW) metric g μν = diag(1, −a, −a, −a), Eq.…”

“…As a further extension, and an analogy to that of f (R) theories [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], non-minimal torsion-matter coupling f (T ) gravity has been proposed and studied [30]. In the previous research [31], using the observation data of type Ia supernovae (SNeIa), cosmic microwave background (CMB), and baryon acoustic oscillations (BAO), we established two concrete f (T ) models with non-minimal torsion-matter coupling extension, and we found that they are successful in describing the observation of the Universe and its large-scale structure and evolution. The joint fitting led to m0 = 0.255 ± 0.010, b0 h 2 = 0.0221 ± 0.0003 and H 0 = 68.54 ± 1.27 for model I and m0 = 0.306 ± 0.010, b0 h 2 = 0.0225±0.0003 and H 0 = 60.97±0.…”

“…Judging from this, it is necessary to combine the cosmological restriction with Solar system effects for the parameters in two models. We have gotten the cosmological restriction using the observation data of SNeIa, CMB and BAO as follows [31]: A = 0.188 ± 0, 048, B = 0.510 ± 0.060 (for Model I); A = 0.633 ± 0.012 and B is a free parameter (for Model II). It is our task in this paper to check whether or not these values of parameters will pass the Solar system tests.…”

Action functional of the Cardassian universe

“…In the Lagrangian of TEGR, the torsion scalar T by contractions of the torsion tensor takes the place of curvature scalar R. The simplest approach in TEGR to modify gravity is f (T ) theory [24,25], whose important advantage is that the field equations are second order but not fourth order as in f (R) theory. Recently, we established two concrete f (T ) models which do not change the successful aspects of the ΛCDM scenario under the error band of fitting values as describing the evolution history of the universe including the radiation-dominated era, the matterdominated era and the present accelerating expansion [26]. We also considered the spherical collapse and virialization in f (T ) gravities [27].…”

Non-minimal coupling of torsion–matter satisfying null energy condition for wormhole solutions

“…They discussed this theory as regards cosmological aspects of an evolving universe and deduced that the universe may represent quintessence, phantom or crossing of phantom-divide line, inflationary era, de Sitter accelerating phase, in short, one has a unified description. In this version of gravity, Nashed [60], Feng et al [61], and Carloni et al [62] studied spherically symmetric solutions, cosmological evolutions, and they compared their results with observational data and phase space analysis, respectively. Garcia and Lobo [63] explored wormhole solutions by a non-minimal curvaturematter coupling taking linear functions, f 1 = R, f 2 = R. They concluded that the wormhole solutions in a realistic manner depend on higher values of the coupling parameter.…”