scholarly journals Inflation and late-time acceleration from a double-well potential with cosmological constant

2016 ◽  
Vol 48 (6) ◽  
Author(s):  
Jaume de Haro ◽  
Emilio Elizalde
2020 ◽  
Vol 17 (05) ◽  
pp. 2050075
Author(s):  
Nasr Ahmed ◽  
Kazuharu Bamba ◽  
F. Salama

In this paper, we study the possibility of obtaining a stable flat dark energy-dominated universe in a good agreement with observations in the framework of Swiss-cheese brane-world cosmology. Two different brane-world cosmologies with black strings have been introduced for any cosmological constant [Formula: see text] using two empirical forms of the scale factor. In both models, we have performed a fine-tuning between the brane tension and the cosmological constant so that the Equation of state (EoS) parameter [Formula: see text] for the current epoch, where the redshift [Formula: see text]. We then used these fine–tuned values to calculate and plot all parameters and energy conditions. The deceleration–acceleration cosmic transition is allowed in both models, and the jerk parameter [Formula: see text] at late-times. Both solutions predict a future dark energy-dominated universe in which [Formula: see text] with no crossing to the phantom divide line. While the pressure in the first solution is always negative, the second solution predicts a better behavior of cosmic pressure where the pressure is negative only in the late-time accelerating era but positive in the early-time decelerating era. Such a positive-to-negative transition in the evolution of pressure helps to explain the cosmic deceleration–acceleration transition. Since black strings have been proved to be unstable by some authors, this instability can actually reflect doubts on the stability of cosmological models with black strings (Swiss-cheese type brane-worlds cosmological models). For this reason, we have carefully investigated the stability through energy conditions and sound speed. Because of the presence of quadratic energy terms in Swiss-cheese type brane-world cosmology, we have tested the new nonlinear energy conditions in addition to the classical energy conditions. We have also found that a negative tension brane is not allowed in both models of the current work as the energy density will no longer be well defined.


Pramana ◽  
2010 ◽  
Vol 74 (3) ◽  
pp. 481-489 ◽  
Author(s):  
Narayan Banerjee ◽  
Sudipta Das ◽  
Koyel Ganguly

2020 ◽  
Vol 29 (09) ◽  
pp. 2050064
Author(s):  
I. Díaz-Saldaña ◽  
J. C. López-Domínguez ◽  
M. Sabido

In this work, we study a Friedmann–Robertson–Walker (FRW) universe derived from a modified entropy–area relationship. By applying the first law of thermodynamics to the so-called apparent horizon and a modified entropy–area relationship, we obtain a modified Friedmann equation. Solving this model for a perfect fluid with vanishing cosmological constant, we find that for early times, the scale factor is the same as that of an FRW universe. In the late-time regime, although the cosmological constant is zero, the asymptotic behavior of the scale factor is exponential, and therefore, we can identify an effective cosmological constant. The origin of the effective cosmological constant can be traced to the modifications of the entropy–area relation.


2017 ◽  
Vol 77 (12) ◽  
Author(s):  
M. Shahalam ◽  
Weiqiang Yang ◽  
R. Myrzakulov ◽  
Anzhong Wang

2010 ◽  
Vol 25 (13) ◽  
pp. 2735-2746 ◽  
Author(s):  
R. RAKHI ◽  
G. V. VIJAYAGOVINDAN ◽  
K. INDULEKHA

In this work, a cosmological model inspired by string/M-theory with fermionic field is taken into consideration. Here it is investigated whether the introduction of a non-Dirac fermionic field — characterized by an interaction term — affects the cosmological evolution. The self-interaction potential is considered as a combination of the scalar and pseudoscalar invariants. It is observed that the fermionic field under consideration behaves like an inflation field for the early universe and later on, as a dark energy field. The late time acceleration becomes more prominent by the addition of the interaction term. There is a slight decrease for the inflation peak as well as for the energy density. We see that the addition of higher-order terms to the fermionic part of Lagrangian does not significantly change either the inflation or the late time acceleration behavior.


2011 ◽  
Vol 08 (06) ◽  
pp. 1179-1188 ◽  
Author(s):  
KOUROSH NOZARI ◽  
F. KIANI

We study the phase space of an extension of the normal DGP cosmology with a cosmological constant on the brane and curvature effect that is incorporated via the Gauss–Bonnet term in the bulk action. We study late-time cosmological dynamics of this scenario within a dynamical system approach. We show that the stable solution of the cosmological dynamics in this model is a de Sitter phase.


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