A new extended quintessence

Wang, Peng; Wu, Puxun; Yu, Hongwei

doi:10.1140/epjc/s10052-012-2245-1

Cited by 39 publications

(48 citation statements)

References 57 publications

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“…However having a final de Sitter expanding Universe may be accessible in models with a nonminimally coupled scalar field to the Ricci scalar (5). Indeed in models other than the symmetron model and with potentials different from (16), such as the exponential potential, the universe may experience a stable de Sitter state at late time [17], or even crosses the phantom divide line [18]. In the other limit, i.e.…”

Section: The Model Z Symmetry Breaking and Cosmic Accelerationmentioning

confidence: 99%

Symmetron and de Sitter attractor in a teleparallel model of cosmology

Sadjadi

2017

J. Cosmol. Astropart. Phys.

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In the teleparallel framework of cosmology, a quintessence with nonminimal couplings to the scalar torsion and a boundary term is considered. A conformal coupling to matter density is also taken into account. It is shown that the model can describe the onset of cosmic acceleration after an epoch of matter dominated era, where dark energy is negligible, via Z 2 symmetry breaking. While the conformal coupling holds the Universe in a state with zero dark energy density in the early epoch, the non-minimal couplings lead the Universe to a stable state with de Sitter expansion at the late time.

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Section: The Model Z Symmetry Breaking and Cosmic Accelerationmentioning

confidence: 99%

Symmetron and de Sitter attractor in a teleparallel model of cosmology

Sadjadi

2017

J. Cosmol. Astropart. Phys.

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“…If R is defined in the metric formalism, then the nonminimal coupling corresponds to the usual extended quintessence [16]. If R is defined in the Palatini formalism however, the so-called new extended quintessence is obtained [39]. When ω = 0, the action reduces to that in general relativity.…”

Section: The Background Field Equationsmentioning

confidence: 99%

“…In [39], Wang, Wu and Yu have studied this new extended quintessence, in which the Ricci scalar is defined in the Palatini formalism rather than in the metric one. Through the dynamical analysis, they found that the effective equation of state of the new extended quintessence can cross the phantom divide line, and moreover, it can realize an oscillation around the −1 line.…”

Section: Introductionmentioning

confidence: 99%

Cosmological perturbations of non-minimally coupled quintessence in the metric and Palatini formalisms

Fan

2015

Physics Letters B

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Editor: M. TroddenCosmological perturbations of the non-minimally coupled scalar field dark energy in both the metric and Palatini formalisms are studied in this paper. We find that on the large scales with the energy density of dark energy becoming more and more important in the low redshift region, the gravitational potential becomes smaller and smaller, and the effect of non-minimal coupling becomes more and more apparent. In the metric formalism the value of the gravitational potential in the non-minimally coupled case with a positive coupling constant is less than that in the minimally coupled case, while it is larger if the coupling constant is negative. This is different from that in the Palatini formalism where the value of gravitational potential is always smaller. Based upon the quasi-static approximation on the sub-horizon scales, the linear growth of matter is also analyzed. We obtain that the effective Newton's constants in the metric and Palatini formalisms have different forms. A negative coupling constant enhances the gravitational interaction, while a positive one weakens it. Although the metric and Palatini formalisms give different linear growth rates, the difference is very small and the current observation cannot distinguish them effectively.

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“…A full investigation on thin film deposition of PPy in the presence of various dopants and characterizations has been carried out by other investigators [38,39] and by the present authors which is published elsewhere [40].…”

Section: Thin Film Deposition and Characteristicsmentioning

confidence: 99%

“…Position and shape of the bipolaron/polaron bands have been shown to be very dependent on environmental factors such as deposition surface [3,9,38], solvent [3,42,43] and the dopant ions [38,39,44,45]. UV-Vis-NIR spectra of thin films of PPy-a-NSA, PPy-(AQSANa,SSCA) and PPy-CSA deposited on modified glass surfaces for 40 min are shown in Fig.…”

Section: Thin Film Deposition and Characteristicsmentioning

confidence: 99%

Patterning ability of conducting polypyrrole thin films by positive photoresist

Mahmoodian

Pourabbas

Hosseini

et al. 2014

J Mater Sci: Mater Electron

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In this paper, patterning ability of ultra-thin films of conducting polypyrrole deposited on silicon wafer surfaces by in situ chemical polymerization in the presence of different anionic dopants including a-naphthalene sulfonic acid, anthraquinone-2-sulfonic acid sodium salt monohydrate/5-sulfosalicylic acid dehydrate and camphor sulfonic acid has been studied. ''Lift-off process'' combined with photolithography is the used method for largearea and easy fabrication of micro patterns of conducting PPy thin films. In this procedure, a self-assembled mono layer of Py-silane is deposited on a patterned surface of a positive photoresist, followed by immersion of the surface into polymerization solution. After polymerization, positive micro pattern of the conducting PPy thin film appears on the surface by lifting-off the post baked positive photo resist by THF. The results showed deposition and patterning of conducting PPy thin films with nanometer thickness and relatively high range of conductivity with features as small as 3-4.5 lm in lateral dimensions on silicon wafer.

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A new extended quintessence

Cited by 39 publications

References 57 publications

Symmetron and de Sitter attractor in a teleparallel model of cosmology

Symmetron and de Sitter attractor in a teleparallel model of cosmology

Cosmological perturbations of non-minimally coupled quintessence in the metric and Palatini formalisms

Patterning ability of conducting polypyrrole thin films by positive photoresist

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