Phantom dark energy models with negative kinetic term

2006 ◽  
Vol 74 (8) ◽  
Author(s):  
Jens Kujat ◽  
Robert J. Scherrer ◽  
A. A. Sen
Keyword(s):  
Dark Energy ◽  
Kinetic Term ◽  
Energy Models ◽  
Phantom Dark Energy

scholarly journals Phantom dark energy from scalar-torsion coupling

2020 ◽  
pp. 2050331
Author(s):  
Nikodem J. Popławski
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Lagrangian Density ◽  
Kinetic Term ◽  
Equivalent Formulation ◽  
Phantom Dark Energy ◽  
General Relativistic ◽  
Theory Of Gravity ◽  
Cartan Theory

We show that a scalar field without a kinetic term in the Lagrangian density, coupled to the covariant divergence of the torsion vector in the Einstein–Cartan theory of gravity, becomes kinetic in its general-relativistic equivalent formulation. The resulting kinetic term is negative: such a scalar field could be a source of phantom dark energy.

scholarly journals Interplay between Swampland and Bayesian Machine Learning in constraining cosmological models

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Emilio Elizalde ◽  
Martiros Khurshudyan
Keyword(s):  
Machine Learning ◽  
Dark Energy ◽  
High Redshift ◽  
Hubble Constant ◽  
State Parameter ◽  
Energy Models ◽  
Important Message ◽  
Phantom Dark Energy ◽  
Probabilistic Machine Learning ◽  
Bayesian Machine Learning

AbstractConstraints on a dark energy dominated Universe are obtained from an interplay Bayesian (Probabilistic) Machine Learning and string Swampland criteria. Unlike in previous studies, here, the field traverse itself has been used to constraint the theory and reveal its connection to the Swampland approach. The field traverse based Bayesian (Probabilistic) Learning approach is applied to two toy models. A parametrization of the Hubble constant is used for the first model, while a parametrization of the deceleration parameter is considered for the second one. The results obtained here allow to estimate how the high-redshift behavior of the Universe will affect the low-redshift one. Moreover, the adopted approach may highlight, in the future, the borders of the Swampland for the low-redshift Universe and help to develop new string-theory motivated dark energy models. The most important message from our study is a hint that the string Swampland criteria might be in tension with recent observations indicating that phantom dark energy cannot be in the Swampland. Finally, another interesting result obtained in our study is a spontaneous sign switch in the dark energy equation of state parameter when the field traverses are in the $$z\in [0,5]$$ z ∈ [ 0 , 5 ] redshift range, a remarkable phenomenon requiring further analysis.

STATEFINDER PARAMETERS FOR PHANTOM DARK ENERGY

2006 ◽  
Vol 21 (16) ◽  
pp. 1305-1311 ◽  
Author(s):  
PUXUN WU ◽  
HONGWEI YU
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Energy Model ◽  
Field Potentials ◽  
Statefinder Parameters ◽  
Phantom Field ◽  
Energy Models ◽  
Phantom Dark Energy ◽  
The Universe

The statefinder parameters were introduced recently to differentiate different dark energy models. In this paper we perform a statefinder diagnostic to the phantom dark energy model with two different phantom field potentials. Our results show that the statefinder diagnostic is rather robust in differentiating not only different dark energy models but also the same kind of models with different potentials which lead to different fate of the universe.

scholarly journals Cosmological constraints of phantom dark energy models

2019 ◽  
Vol 26 ◽  
pp. 100391 ◽  
Author(s):  
Amine Bouali ◽  
Imanol Albarran ◽  
Mariam Bouhmadi-López ◽  
Taoufik Ouali
Keyword(s):  
Dark Energy ◽  
Cosmological Constraints ◽  
Energy Models ◽  
Phantom Dark Energy

scholarly journals Cosmological Perturbations in Phantom Dark Energy Models

Universe ◽  
2017 ◽  
Vol 3 (1) ◽  
pp. 22
Author(s):  
Imanol Albarran ◽  
Mariam Bouhmadi-López ◽  
João Morais
Keyword(s):  
Dark Energy ◽  
Cosmological Perturbations ◽  
Energy Models ◽  
Phantom Dark Energy

SCALING DARK ENERGY IN A FIVE-DIMENSIONAL BOUNCING COSMOLOGICAL MODEL

2005 ◽  
Vol 14 (11) ◽  
pp. 1947-1957 ◽  
Author(s):  
LIXIN XU ◽  
HONGYA LIU
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cosmological Model ◽  
Cold Dark Matter ◽  
Coincidence Problem ◽  
Energy Models ◽  
Phantom Dark Energy ◽  
Hyperbolic Form ◽  
Induced Matter ◽  
The Universe

We consider a five-dimensional Ricci flat bouncing cosmological model in which the four-dimensional induced matter contains two components at late times — the cold dark matter (CDM) + baryons and dark energy. We find that the arbitrary function f(z) contained in the solution plays a similar role as the potential V(ϕ) in quintessence and phantom dark energy models. To resolve the coincidence problem, it is generally believed that there is a scaling stage in the evolution of the universe. We analyze the condition for this stage and show that a hyperbolic form of the function f(z) can work well in this property. We find that during the scaling stage (before z ≈ 2), the dark energy behaves like (but not identical to) a cold dark matter with an adiabatic sound speed [Formula: see text] and px ≈ 0. After z ≈ 2, the pressure of the dark energy becomes negative. The transition from deceleration to acceleration happens at zT ≈ 0.8 which, as well as other predictions of the 5D model, agrees with current observations.

scholarly journals Cosmological constraints of interacting phantom dark energy models

2021 ◽  
pp. 100907
Author(s):  
Amine Bouali ◽  
Imanol Albarran ◽  
Mariam Bouhmadi-López ◽  
Ahmed Errahmani ◽  
Taoufik Ouali
Keyword(s):  
Dark Energy ◽  
Cosmological Constraints ◽  
Energy Models ◽  
Phantom Dark Energy
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