Sign Switching Dark Energy from a Running Barrow Entropy

Gennaro, Sofia Di; Ong, Yen Chin

doi:10.3390/universe8100541

Cited by 30 publications

(10 citation statements)

References 82 publications

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“…Fourthly, we find that the novel double-field pure K-essence can incorporate the scenario of sign-switching dark energy like the ones investigated in [38][39][40] by appropriately selecting the values of parameters s 2 , c 2 and c 1 , s 1 in the energy density, Equation (51), for example. It is found that the sign-switching dark energy is asymptotically positive and vanishing, but negative at the Big Bang.…”

Section: Conclusion and Discussionmentioning

confidence: 91%

The Equation of State of Novel Double-Field Pure K-Essence for Inflation, Dark Matter and Dark Energy

Gao

2024

Universe

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K-essence theories are usually studied in the framework of a single scalar field ϕ. Namely, the Lagrangian of K-essence is the function of the single scalar field ϕ and its covariant derivative. However, in this paper, we explore a double-field pure K-essence, i.e., the corresponding Lagrangian is the function of covariant derivatives of double scalar fields without a dependency on scalar fields themselves. This is why we call it double-field pure K-essence. The novelty of this K-essence is that its Lagrangian contains the quotient term of the kinetic energies from the two scalar fields. This results in the presence of many interesting features; for example, the equation of state can be arbitrarily small and arbitrarily large. In comparison, the range of the equation of state for quintessence is −1 to +1. Interestingly, this novel K-essence can play the role of an inflation field, dark matter, or dark energy by appropriately selecting the expressions of Lagrangian.

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Section: Conclusion and Discussionmentioning

confidence: 91%

The Equation of State of Novel Double-Field Pure K-Essence for Inflation, Dark Matter and Dark Energy

Gao

2024

Universe

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“…For the sake of completeness, we also mention the papers in refs. [109,110] where the authors explored cosmological consequences and modified gravity for Barrow entropy.…”

Section: Generalised Second Lawmentioning

confidence: 99%

Modified Friedmann equations from fractional entropy

Çoker,

Ökcü,

Aydiner

2023

EPL

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Based on the fractional black hole entropy \cite{Jalalzadeh2021}, we derive the modified Friedmann equations from two different frameworks. First, we consider the modifications of Friedmann equations from the first law of thermodynamics at the apparent horizon. We show that the generalized second law (GSL) of thermodynamics always holds in a region bounded by the apparent horizon. Then, we obtain Friedmann equations from Verlinde's entropic gravity framework. We also compute the fractional corrections to deceleration parameter $q$ in flat case $k=0$ for both frameworks. Furthermore, we consider the time to reach the initial singularity for the two frameworks. The results indicate that {\color{blue} the initial singularity is accessible for both frameworks. However, fractional effects may provide a constraint on the equation of state parameter in the entropic gravity scenario since the time is imaginary for $-2/3\alpha<\omega<-1/3$.

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“…This argues that the entropic cosmology, in absence of matter fields, results in a de-Sitter spacetime, or equivalently, an eternal inflation having no exit. Therefore, in order to obtain a viable inflation, one needs to incorporate either of the following possibilities-(a) the entropic parameters slowly vary with the cosmic expansion of the universe (one may see [53] where the authors studied a energy scale-varying entropic index that could lead to new physics in the early universe), or (b) some matter fields inside of the horizon. In the present work, we will concentrate on the second possibility, where the matter field is taken to be a minimally coupled scalar field with a power law potential.…”

Section: Modified Cosmology With Generalized Entropymentioning

confidence: 99%

Entropic Inflation in Presence of Scalar Field

Odintsov,

D’Onofrio,

Paul

2023

Universe

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In spirit of the recently proposed four-parameter generalized entropy of apparent horizon, we investigate inflationary cosmology where the matter field inside of the horizon is dominated by a scalar field with a power law potential (i.e., the form of ϕn where ϕ is the scalar field under consideration). Actually without any matter inside of the horizon, the entropic cosmology leads to a de-Sitter spacetime, or equivalently, an eternal inflation with no exit. Thus in order to achieve a viable inflation, we consider a minimally coupled scalar field inside the horizon, and moreover, with the simplest quadratic potential. It is well known that the ϕ2 potential in standard scalar field cosmology is ruled out from inflationary perspective as it is not consistent with the recent Planck 2018 data; (here it may be mentioned that in the realm of “apparent horizon thermodynamics”, the standard scalar field cosmology is analogous to the case where the entropy of the apparent horizon is given by the Bekenstein–Hawking entropy). However, the story becomes different if the horizon entropy is of generalized entropic form, in which case, the effective energy density coming from the horizon entropy plays a significant role during the evolution of the universe. In particular, it turns out that in the context of generalized entropic cosmology, the ϕ2 potential indeed leads to a viable inflation (according to the Planck data) with a graceful exit, and thus the potential can be made back in the scene.

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Sign Switching Dark Energy from a Running Barrow Entropy

Cited by 30 publications

References 82 publications

The Equation of State of Novel Double-Field Pure K-Essence for Inflation, Dark Matter and Dark Energy

The Equation of State of Novel Double-Field Pure K-Essence for Inflation, Dark Matter and Dark Energy

Modified Friedmann equations from fractional entropy

Entropic Inflation in Presence of Scalar Field

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