共查询到20条相似文献,搜索用时 31 毫秒
1.
In this paper we study inflationary dynamics with a scalar field in an inverse coshyperbolic potential in the braneworld model.
We note that a sufficient inflation may be obtained with the potential considering slow-roll approximation in the high energy
limit. We determine the minimum values of the initial inflaton field required to obtain sufficient inflation and also determine
the relevant inflationary parameters. The numerical values of spectral index of the scalar perturbation spectrum are determined
by varying the number of e-foldings for different initial values of the inflaton field. The result obtained here is in good
agreement with the current observational limits.
相似文献
2.
We construct a warm inflation model with inflaton field non-minimally coupled to induced gravity on a warped DGP brane. We
incorporate possible modification of the induced gravity on the brane in the spirit of f(R)-gravity. We study cosmological perturbations in this setup. In the case of two field inflation such as warm inflation, usually
entropy perturbations are generated. While it is expected that in the case of one field inflation these perturbations to be
removed, we show that even in the absence of the radiation field, entropy perturbations are generated in our setup due to
non-minimal coupling and modification of the induced gravity. We study the effect of dissipation on the inflation parameters
of this extended braneworld scenario. 相似文献
3.
Mubasher Jamil K. Karami A. Sheykhi 《International Journal of Theoretical Physics》2011,50(10):3069-3077
Motivated by recent works (Saridakis in Phys. Lett. B 660:138, 2008; Sheykhi in Int. J. Mod. Phys. D 19(3):305, 2010), we investigate the new agegraphic model of dark energy in the framework of RS II braneworld. We also include the case of
variable gravitational constant G in our model. Moreover, we reconstruct the potential and the dynamics of the quintessence, tachyon, K-essence and dilaton
scalar field models according to the evolutionary behavior of the new agegraphic dark energy model in RS II braneworld cosmology
including varying G. 相似文献
4.
F. Salamate I. Khay A. Safsafi H. Chakir M. Bennai 《Moscow University Physics Bulletin》2018,73(4):405-412
We study Chaplygin gas as a candidate for inflation in the context of braneworld inflationary model. We investigate this model in the framework of the Randall–Sundrum type II, considering a original and generalized Chaplygin gas. We use inverse power law potential to examine the behavior of some inflationary spectrum parameters such as the spectral index ns, the ratio r and the running of the scalar spectral index dns/dlnk, our results are in agreement with recent observational data for a particular choice of e-folding number N and parameters space of the model. 相似文献
5.
Xiong-Wei Liu Shu-Zheng Yang Shi-Wu Chen Wen-Fu Wang 《International Journal of Theoretical Physics》2009,48(5):1478-1484
We find a new exact inflationary solution to non-minimally coupled scalar field from a specific H(φ). The inflation is driven by the evolution of the scalar field with a new inflation potential. The spectral index of the
scalar density fluctuations n
s
is consistent with the result of WMAP3 for the power-law flat ΛCDM model. Our solution relaxes the constraint to the quartic
coupling constant, e.g. when ξ=103, λ≤8.9×10−11. 相似文献
6.
We study a supergravity D-term chaotic inflationary model, in the context of the braneworld scenario, in particular we consider the Randal1-Sundrum model type 2. Using the latest release from the combination of WMAP9, eCMB, BAO, and Ho, we show that the inflation observables depend only on the number ore-folds N. We also derive all known spectrum inflationary parameters, which are widely consistent with WMAP9 data for a particular choice of values N specially for the scalar spectral index ns and the ratio r. However, the running of the scalar spectral index dns/dlnk is now excluded from the range given by the latest observational measurements. 相似文献
7.
We derive the implications for anisotropies in the cosmic microwave background following from a model of inflation in which a bare cosmological constant is gradually screened by an infrared process in quantum gravity. The model predicts that the amplitude of scalar perturbations is AS = (2.0 ± 0.2) · 10—5, that the tensor-to-scalar ratio is r ≈︂ 1.7 · 10—3, and that the scalar and tensor spectral indices are n ≈︂ 0.97 and nT ≈︂ —2.8 · 10—4, respectively. By comparing the model's power spectrum with the COBE 4-year RMS quadrupole, the mass scale of inflation is determined to be M = (0.72 ± 0.03) · 1016 GeV. At this scale the model produces about 108 e-foldings of inflation, so another prediction is Ω = 1. PACS numbers: 04.60.-m, 98.80.Cq 相似文献
8.
This work deals with braneworld models driven by real scalar fields with nonstandard dynamics. We develop the first-order formalism for models with standard gravity but with the scalar fields having generalized dynamics. We illustrate the results with examples of current interest, and we find analytical and numerical solutions for warp factors and scalar fields. The results indicate that the generalized braneworld scenario is classically stable, and capable of localizing gravity. 相似文献
9.
Here, we investigate the cosmological implications of Holographic Dark Energy (HDE) in the DGP braneworld model of the universe.
Taking HDE in DGP braneworld, we investigate the model of non-interacting dark energy and derive its equation of state. Subsequently,
we study the correspondence between k-essence, tachyon, dilaton, hessence and DBI-essence dark energy with the non-interacting
HDE in a flat DGP braneworld and reconstruct the corresponding scalar potentials which describe the dynamics of the scalar
fields. Also we study the correspondence between above mentioned scalar potentials and effective dark energy coming from DGP
braneworld in the absence of HDE and in this situation, the potentials are reconstructed. 相似文献
10.
The standard Model Higgs scalar boson minimally coupled to gravity does not take part in the inflation of the early universe
if its mass exceeds a threshold value, which is m
H
min = 142 GeV in the tree approximation for the potential of the scalar. Two-loop corrections modify this estimate, which becomes
m
H
min = 150 ± 3 GeV. Therefore, higher order corrections of perturbation theory have quite a controllable moderate character, but
they are numerically important for experiments. 相似文献
11.
Zhe Chang Ming-Hua Li Xin Li Sai Wang 《The European Physical Journal C - Particles and Fields》2012,72(3):1915
We investigate the possible effect of cosmological-constant type dark energy during the inflation period of the early universe.
This is accommodated by a new dispersion relation in de Sitter space. The modified inflation model of a minimally coupled
scalar field is still able to yield an observation-compatible scale-invariant primordial spectrum, simultaneously having the
potential to generate a spectrum with lower power at large scales. A qualitative match to the WMAP 7-year data is presented.
We obtain an Ω
Λ
of the same order of that in the Λ-CDM model. Possible relations between the de Sitter scenario and Doubly Special Relativity (DSR) are also discussed. 相似文献
12.
In this article, our aim is to consider inflation, dark energy and dark matter in the framework of a real scalar field. To
this end, we use the quintessence approach. We have tried a real scalar field with a specific self-interaction potential in
a spacially flat universe. Numerical results indicate that this potential can drive the expansion of the universe in three
distinct phases. The first phase behaves as an inflationary expansion. For this stage, setting the scalar field’s initial
value to ϕ
0≥1.94 leads to N 3 68\mathcal{N}\geq 68 favored by observation. After the inflationary phase, the scalar field starts an oscillatory behavior which averages to a
=0\bar{w}=0 fluid. This stage can be taken as a cold dark matter (p≈0) epoch expected from works on the structure formation issue. Observations and cosmological models indicate that t
inf
≈10−35 s and the matter dominated lasts for t
m
≈1017 s, hence
(\fractmtinf)obs ? 1052(\frac{t_{m}}{t_{inf}})_{obs}\approx10^{52}. We have shown that the present model can satisfy such a constraint. Finally, the scalar field leaves the oscillatory behavior
and once again enters a second inflationary stage which can be identified with the recent accelerated expansion of the universe.
We have also compared our model with the ΛCDM model and have found a very good agreement between the equation of state parameter of both of models during the DM and DE
era. 相似文献
13.
We consider a supersymmetric hybrid inflation model with two inflaton fields. The superpotential during inflation is dominated
by W=(κS+κ′S′)M
2, where S, S′ are inflatons carrying the same U(1)
R
charge, κ, κ′ are dimensionless couplings, and M (∼1015−16 GeV) is a dimensionful parameter associated with a symmetry breaking scale. One light mass eigenstate drives inflation, while
the other heavier mass eigenstate is stuck to the origin. The smallness of the lighter inflaton mass for the scalar spectral
index n
s
≈0.96, which is the center value of WMAP7, can be controlled by the ratio κ′/κ through the supergravity corrections. We also discuss the possibility of the two field inflation and large non-Gaussianity
in this setup. 相似文献
14.
In this work, we study the quasinormal modes (QNMs) of scalar field coupling to Einstein’s tensor in charged braneworld black hole. The shape of the potential function is illustrated and we find that lower coupling constant leads to more stable field. We then apply six-order WKB approximation to calculate the quasinormal frequencies (QNF) in weaker coupling field, and depict the dependence of the oscillation frequency on the coupling constant. Furthermore, we use finite difference method to shape the evolution of the coupling field and find that coupling field with lower multipole numbers l corresponds to stable field, while higher l tends to lead to instability when the coupling constant is larger than a threshold value. Finally the fitting curve of such threshold value is given numerically. 相似文献
15.
Qing Gao 《中国科学:物理学 力学 天文学(英文版)》2018,61(7):070411
We discuss the constant-roll inflation with constant ∈_2 and constant η. By using the method of Bessel function approximation, the analytical expressions for the scalar and tensor power spectra, the scalar and tensor spectral tilts, and the tensor to scalar ratio are derived up to the first order of ∈_1. The model with constant ∈_2 is ruled out by the observations at the 3σ confidence level, and the model with constant η is consistent with the observations at the 1σ confidence level. The potential for the model with constant η is also obtained from the Hamilton-Jacobi equation. Although the observations constrain the constant-roll inflation to be the slow-roll inflation, the ns-r results from the constant-roll inflation are not the same as those from the slow-roll inflation even when η~ 0.01. 相似文献
16.
Nandinii Barbosa-Cendejas Alfredo Herrera-Aguilar Konstantinos Kanakoglou Ulises Nucamendi Israel Quiros 《General Relativity and Gravitation》2014,46(1):1-26
We consider a scalar thick brane configuration arising in a 5D theory of gravity coupled to a self-interacting scalar field in a Riemannian manifold. We start from known classical solutions of the corresponding field equations and elaborate on the physics of the transverse traceless modes of linear fluctuations of the classical background, which obey a Schrödinger-like equation. We further consider two special cases in which this equation can be solved analytically for any massive mode with $m^2\ge 0$ , in contrast with numerical approaches, allowing us to study in closed form the massive spectrum of Kaluza–Klein (KK) excitations and to analytically compute the corrections to Newton’s law in the thin brane limit. In the first case we consider a novel solution with a mass gap in the spectrum of KK fluctuations with two bound states—the massless 4D graviton free of tachyonic instabilities and a massive KK excitation—as well as a tower of continuous massive KK modes which obey a Legendre equation. The mass gap is defined by the inverse of the brane thickness, allowing us to get rid of the potentially dangerous multiplicity of arbitrarily light KK modes. It is shown that due to this lucky circumstance, the solution of the mass hierarchy problem is much simpler and transparent than in the thin Randall–Sundrum (RS) two-brane configuration. In the second case we present a smooth version of the RS model with a single massless bound state, which accounts for the 4D graviton, and a sector of continuous fluctuation modes with no mass gap, which obey a confluent Heun equation in the Ince limit. (The latter seems to have physical applications for the first time within braneworld models). For this solution the mass hierarchy problem is solved with positive branes as in the Lykken–Randall (LR) model and the model is completely free of naked singularities. We also show that the scalar–tensor system is stable under scalar perturbations with no scalar modes localized on the braneworld configuration. 相似文献
17.
We consider a scenario of hybrid inflation in the framework of the minimal supersymmetric SU(5) model, compatible, for a quite wide range of initial conditions for inflation scalar fields, with inflation efficiency, monopole dilution and perturbation constraints. 相似文献
18.
Miguel A. García-Aspeitia Juan A. Magaña Tonatiuh Matos 《General Relativity and Gravitation》2012,44(3):581-601
Following a previous work (García-Aspeitia in Gen Rel Grav 43:315–329, 2011), we further study the behavior of a real scalar field in a hidden brane in a configuration of two branes embedded in a five
dimensional bulk. We find an expression for the equation of state for this scalar field in the visible brane in terms of the
fields of the hidden one. Additionally, we investigated the perturbations produced by this scalar field in the visible brane
with the aim to study their dynamical properties. Our results show that if the kinetic energy of the scalar field dominates
during the early universe the perturbed scalar field could mimic the observed dynamics for the dark matter in the standard
paradigm. Thus, the scalar field dark matter hypothesis in the context of braneworld theory could be an interesting alternative
to the nature of dark matter in the Universe. 相似文献
19.
Qing Gao 《中国科学:物理学 力学 天文学(英文版)》2017,60(9):090411
Using the relations between the slow-roll parameters and the power spectra for the single field slow-roll inflation, we derive the scalar spectral tilt n_s and the tensor to scalar ratio r for the constant slow-roll inflation, and obtain the constraint on the slow-roll parameter η from the Planck 2015 results. The inflationary potential for the constant slow-roll inflation is then reconstructed in the framework of both general relativity and the scalar-tensor theory of gravity, and compared with the recently reconstructed E model potential. In the strong coupling limit, we show that the η attractor is reached. 相似文献
20.
We propose new brane world models arising from a scalar field in the bulk. In these examples, the induced on-brane line element
is de Sitter (or anti de Sitter) and the bulk (five dimensional) Einstein equations can be exactly solved to obtain warped
spacetimes. The solutions thus derived are single and two-brane models—one with thin branes while the other one of the thick variety. The field profiles and the potentials are obtained and analysed for each case. We note that for the thick brane scenario the field profile resembles a kink, whereas for one or more thin branes, it is finite and bounded in the domain of the extra dimension. We have also addressed the localisation of gravity
and other matter fields on the brane for these braneworld models. 相似文献