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Articles de revues sur le sujet « Phantom scalar field »

Auteur : Grafiati
Publié le 9 mars 2023
Mis à jour le 10 mars 2023

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1

HASSAÏNE, MOKHTAR. « PHANTOM FIELD FROM CONFORMAL INVARIANCE ». Modern Physics Letters A 22, no 04 (10 février 2007) : 307–16. http://dx.doi.org/10.1142/s0217732307021093.

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We establish a correspondence between a conformally invariant complex scalar field action (with a conformal self-interaction potential) and the action of a phantom scalar field minimally coupled to gravity (with a cosmological constant). In this correspondence, the module of the complex scalar field is used to relate conformally the metrics of both systems while its phase is identified with the phantom scalar field. At the level of the equations, the correspondence allows to map solution of the conformally nonlinear Klein–Gordon equation with vanishing energy–momentum tensor to solution of a phantom scalar field minimally coupled to gravity with cosmological constant satisfying a massless Klein–Gordon equation. The converse is also valid with the advantage that it offers more possibilities owing to the freedom of rewriting a metric as the conformal transformation of another metric. In three dimensions, the coupling of this matter action to conformal gravity is put in equivalence with topologically massive gravity with a cosmological constant and with a phantom source. Finally, we provide some examples of this correspondence.
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DZHUNUSHALIEV, VLADIMIR, VLADIMIR FOLOMEEV, SHYNARAY MYRZAKUL et RATBAY MYRZAKULOV. « PHANTOM THICK BRANE IN 5D BULK ». Modern Physics Letters A 23, no 33 (30 octobre 2008) : 2811–19. http://dx.doi.org/10.1142/s0217732308028296.

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A model of a thick brane in 5D bulk supported by two phantom scalar fields is considered. The comparison with a thick brane supported by two usual scalar fields is carried out. The distinctions between a thick brane supported by one usual scalar field and our model have been pointed out.
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3

Zhang, Limei, Xiaoxiong Zeng et Zhonghua Li. « AdS Black Hole with Phantom Scalar Field ». Advances in High Energy Physics 2017 (2017) : 1–7. http://dx.doi.org/10.1155/2017/4940187.

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We present an AdS black hole solution with Ricci flat horizon in Einstein-phantom scalar theory. The phantom scalar fields just depend on the transverse coordinates x and y, which are parameterized by the parameter α. We study the thermodynamics of the AdS phantom black hole. Although its horizon is a Ricci flat Euclidean space, we find that the thermodynamical properties of the black hole solution are qualitatively the same as those of AdS Schwarzschild black hole. Namely, there exists a minimal temperature and the large black hole is thermodynamically stable, while the smaller one is unstable, so there is a so-called Hawking-Page phase transition between the large black hole and the thermal gas solution in the AdS space-time in Poincare coordinates. We also calculate the entanglement entropy for a strip geometry dual to the AdS phantom black holes and find that the behavior of the entanglement entropy is qualitatively the same as that of the black hole thermodynamical entropy.
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Chen, Xiu-Wu, Wei-Qiang Zheng et Ji-Yan Chen. « Localization and mass spectra of bulk bosonic fields on de Sitter thick branes ». International Journal of Modern Physics A 30, no 26 (18 septembre 2015) : 1550151. http://dx.doi.org/10.1142/s0217751x15501511.

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A thick de Sitter brane constructed by a canonical or phantom scalar field and localization mass spectra of the bulk scalar and vector fields on the de Sitter brane is investigated. It is found that the scalar and vector zero modes are always localized on the de Sitter brane. For the de Sitter brane generated by a canonical scalar field, the spectrum of the scalar (vector) KK modes consists of one or two bound modes (one bound mode) and a set of continuous modes. However, for the de Sitter brane generated by a phantom scalar field, the spectrum of the scalar (vector) KK modes consists of two (one) or more bound KK modes as well as a set of continuous modes. The continuous spectrum on both branes starts with a same value for the scalar (vector) KK modes.
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ANDRIANOV, ALEXANDER A., FRANCESCO CANNATA et ALEXANDER Y. KAMENSHCHIK. « PHANTOM UNIVERSE FROM CPT SYMMETRIC QFT ». International Journal of Modern Physics D 15, no 08 (août 2006) : 1299–310. http://dx.doi.org/10.1142/s021827180600911x.

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We develop a generalization of semiclassical field theory for the case of non-Hermitian Hamiltonians with CPT symmetry and construct a classical cosmological, scalar-field based model describing a smooth transition from ordinary dark energy to the phantom one. Our model arises from a Lagrangian with a complex potential leading to a non-trivial vacuum with real vacuum energy. Equivalence with models involving two scalar fields one of which is phantom-like is discussed.
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RUDRA, PRABIR. « EMERGENT UNIVERSE WITH EXOTIC MATTER IN LOOP QUANTUM COSMOLOGY, DGP BRANE-WORLD AND KALUZA–KLEIN COSMOLOGY ». Modern Physics Letters A 27, no 33 (24 octobre 2012) : 1250189. http://dx.doi.org/10.1142/s0217732312501891.

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In this work we have investigated the emergent scenario of the Universe described by loop quantum cosmology model, DGP brane model and Kaluza–Klein cosmology. Scalar field along with barotropic fluid as normal matter is considered as the matter content of the Universe. In loop quantum cosmology it is found that the emergent scenario is realized with the imposition of some conditions on the value of the density of normal matter in case of normal and phantom scalar field. This is a surprising result indeed considering the fact that scalar field is the dominating matter component! In case of tachyonic field, emergent scenario is realized with some constraints on the value of ρ1 for both normal and phantom tachyon. In case of DGP brane-world realization of an emergent scenario is possible almost unconditionally for normal and phantom fields. Plots and table have been generated to testify this fact. In case of tachyonic field emergent scenario is realized with some constraints on [Formula: see text]. In Kaluza–Klein cosmology emergent scenario is possible only for a closed Universe in case of normal and phantom scalar field. For a tachyonic field, realization of emergent Universe is possible for all models (closed, open and flat).
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7

ZHANG, XIAO-FEI, HONG LI, YUN-SONG PIAO et XINMIN ZHANG. « TWO-FIELD MODELS OF DARK ENERGY WITH EQUATION OF STATE ACROSS -1 ». Modern Physics Letters A 21, no 03 (30 janvier 2006) : 231–41. http://dx.doi.org/10.1142/s0217732306018469.

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In this paper, we study the possibility of building two-field models of dark energy with equation of state across -1. Specifically we will consider two classes of models: one consists of two scalar fields (quintessence + phantom) and another includes one scalar (phantom) and one spinor field (neutrino). Our studies indicate to some extent that two-field models give rise to a simple realization of the dynamical dark energy model with the equation of state across w=-1.
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8

NOZARI, KOUROSH, et S. DAVOOD SADATIAN. « COMPARISON OF FRAMES : JORDAN VERSUS EINSTEIN FRAME FOR A NON-MINIMAL DARK ENERGY MODEL ». Modern Physics Letters A 24, no 38 (14 décembre 2009) : 3143–55. http://dx.doi.org/10.1142/s0217732309031053.

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We construct a dark energy model where a scalar field non-minimally coupled to gravity plays the role of the dark component. We compare cosmological consequences of this non-minimal coupling of the scalar field and gravity in the spirit of the dark energy paradigm in Jordan and Einstein frames. Some important issues such as phantom divide line crossing, existence of the bouncing solutions and the stability of the solutions are compared in these two frames. We show that while a non-minimally coupled scalar field in the Jordan frame is a suitable dark energy component with capability to realize phantom divide line crossing, its conformal transformation in the Einstein frame does not have this capability. The conformal transformation from Jordan frame to Einstein frame transforms the equation of state parameter of the dark energy component to its minimal form with a redefined scalar field and in this case it is impossible to realize a phantom phase with possible crossing of the phantom divide line.
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9

CHAVES, MAX, et DOUGLAS SINGLETON. « PHANTOM ENERGY FROM GRADED ALGEBRAS ». Modern Physics Letters A 22, no 01 (10 janvier 2007) : 29–40. http://dx.doi.org/10.1142/s0217732307022372.

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We construct a model of phantom energy using the graded Lie algebra SU(2/1). The negative kinetic energy of the phantom field emerges naturally from the graded Lie algebra, resulting in an equation of state with w < -1. The model also contains ordinary scalar fields and anticommuting (Grassmann) vector fields which can be taken as two-component dark matter. A potential term is generated for both the phantom fields and the ordinary scalar fields via a postulated condensate of the Grassmann vector fields. Since the phantom energy and dark matter arise from the same Lagrangian, the phantom energy and dark matter of this model are coupled via the Grassmann vector fields. In the model presented here phantom energy and dark matter come from a gauge principle rather than being introduced in an ad hoc manner.
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10

El-Nabulsi, Rami Ahmad. « Asymptotically Static Universe Dominated by Phantom Energy ». Zeitschrift für Naturforschung A 70, no 2 (1 février 2015) : 101–8. http://dx.doi.org/10.1515/zna-2014-0242.

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AbstractIn this article, we investigated a generalised scalar field cosmology characterised by a time-dependent coupling function, a time-dependent cosmological constant, a chameleonic field, and a time-dependent equation of state parameter. Based on a particular choice of the Hubble parameter as function of the scalar field and its time derivative, we have investigated the dynamics of the Friedmann–Robertson–Walker flat universe. We have observed that for a particular choice of the free parameters in the theory, the universe accelerates with time and asymptotically tends toward a static universe. For specific values of the free parameters, the asymptotically static universe may be dominated by phantom energy or a cosmological constant without the need to implement in the theory multiple scalar fields or additional interactions. It is also pointed out that an asymptotically static universe is as well one special class of solutions for Horndeski and generalised galileons cosmologies. Special properties and features are discussed accordingly.
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11

Zhou, Jian-hua, Hui-qing Lu, Wei Fang et Chen-xing Wei. « A comparison of phantom linear scalar field and non-linear Born-Infeld scalar field ». Journal of Shanghai University (English Edition) 12, no 5 (octobre 2008) : 405–9. http://dx.doi.org/10.1007/s11741-008-0506-3.

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12

LU, H. Q. « PHANTOM COSMOLOGY WITH A NONLINEAR BORN–INFELD TYPE SCALAR FIELD ». International Journal of Modern Physics D 14, no 02 (février 2005) : 355–62. http://dx.doi.org/10.1142/s021827180500513x.

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Recent many physicists suggest that the dark energy in the universe might result from the Born–Infeld (B–I) type scalar field of string theory. The universe of B–I type scalar field with potential can undergo a phase of accelerating expansion. The corresponding equation of state parameter lies in the range of -1<ω<-⅓. The equation of state parameter of B–I type scalar field without potential lies in the range of 0≤ω≤1. We find that weak energy condition and strong energy condition are violated for phantom B–I type scalar field. The equation of state parameter lies in the range of ω<-1.
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13

Kratovitch, P. V., I. M. Potashov, Ju V. Tchemarina et A. N. Tsirulev. « Topological geons with self-gravitating phantom scalar field ». Journal of Physics : Conference Series 934 (décembre 2017) : 012047. http://dx.doi.org/10.1088/1742-6596/934/1/012047.

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14

Kleidis, K., et V. K. Oikonomou. « Loop quantum cosmology scalar field models ». International Journal of Geometric Methods in Modern Physics 15, no 05 (2 avril 2018) : 1850071. http://dx.doi.org/10.1142/s0219887818500718.

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In this work, we use the Loop Quantum Cosmology (LQC) modified scalar–tensor reconstruction techniques in order to investigate how bouncing and inflationary cosmologies can be realized. With regard to the inflationary cosmologies, we shall be interested in realizing the intermediate inflation and the Type IV singular inflation, while with regard to bouncing cosmologies, we shall realize the superbounce and the symmetric bounce. In all the cases, we shall find the kinetic term of the LQC holonomy corrected scalar–tensor theory and the corresponding scalar potential. In addition, we shall include a study of the effective Equation of State (EoS), emphasizing at the early- and late-time eras. As we demonstrate, in some cases it is possible to have a nearly de Sitter EoS at the late-time era, a result that could be interpreted as the description of a late-time acceleration era. Also, in all cases we shall examine the dynamical stability of the LQC holonomy corrected scalar-tensor theory, and we shall confront the results with those coming from the corresponding classical dynamical stability theory. The most appealing cosmological scenario is that of a Type IV singular inflationary scenario, in which the singularity may occur at the late-time era. As we demonstrate, for this model, during the dark energy era, a transition from non-phantom to a phantom dark energy era occurs.
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15

Chattopadhyay, Surajit, et Ujjal Debnath. « Generalized second law of thermodynamics in the presence of interacting tachyonic field and scalar (phantom) field ». Canadian Journal of Physics 88, no 12 (décembre 2010) : 933–38. http://dx.doi.org/10.1139/p10-094.

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In the present work, we consider the tachyonic field, the phantom field, and the scalar field in both interacting and non-interacting situations and investigate the validity of the generalized second law of thermodynamics in a flat FRW universe. We find that in all cases, except for the phantom field dominated universe, the derivative of the entropy remains at negative level and increases with the decrease in redshift.
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16

Kabak, Ali, et Sezgin Aygün. « Scalar field solutions for anisotropic universe models in various gravitation theories ». International Journal of Geometric Methods in Modern Physics 17, no 02 (13 janvier 2020) : 2050025. http://dx.doi.org/10.1142/s0219887820500255.

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In this study, we have investigated homogeneous and anisotropic Marder and Bianchi type I universe models filled with normal and phantom scalar field matter distributions with [Formula: see text] in [Formula: see text] gravitation theory (T. Harko et al., Phys. Rev. D 84 (2011) 024020). In this model, [Formula: see text] is the Ricci scalar and [Formula: see text] is the trace of energy–momentum tensor. To obtain exact solutions of modified field equations, we have used anisotropy feature of the universe and different scalar potential models with [Formula: see text] function. Also, we have obtained general relativity (GR) solutions for normal and phantom scalar field matter distributions in Marder and Bianchi type I universes. Additionally, we obtained the same scalar function values by using different scalar field potentials for Marder and Bianchi type I universe models with constant difference in [Formula: see text] gravity and GR theory. From obtained solutions, we get negative cosmological term value for [Formula: see text] constant scalar potential model with Marder and Bianchi type I universes in GR theory. These results agree with the studies of Maeda and Ohta, Aktaş et al. also Biswas and Mazumdar. Finally, we have discussed and compared our results in gravitation theories.
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Chattopadhyay, Surajit, Antonio Pasqua et Irina Radinschi. « Accreting Scalar-Field Models of Dark Energy Onto Morris-Thorne Wormhole ». Zeitschrift für Naturforschung A 71, no 10 (1 octobre 2016) : 949–60. http://dx.doi.org/10.1515/zna-2016-0241.

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AbstractThe present paper reports a study on accreting tachyon, Dirac-Born-Infeld essence and h-essence scalar field models of dark energy onto Morris-Thorne wormhole. Using three different parameterisation schemes and taking $H\, = \,{H_0}\, + \,{{{H_1}} \over t}$, we have derived the mass of the wormhole for all of the three parameterisation schemes that are able to get hold of both quintessence and phantom behaviour. With suitable choice of parameters, we observed that accreting scalar field dark energy models are increasing the mass of the wormhole in the phantom phase and the mass is decreasing in the quintessence phase. Finally, we have considered accretion with power law form of scale factor and without any parameterisation scheme for the equation of state parameter and observed the fact that phantom-type dark energy supports the existence of wormholes.
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18

Leon, Genly, Alfredo D. Millano et Andronikos Paliathanasis. « Scalar Field Cosmology from a Modified Poisson Algebra ». Mathematics 11, no 1 (27 décembre 2022) : 120. http://dx.doi.org/10.3390/math11010120.

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We investigate the phase space of a scalar field theory obtained by minisuperspace deformation. We consider quintessence or phantom scalar fields in the action that arises from minisuperspace deformation on the Einstein–Hilbert action. We use a modified Poisson algebra where Poisson brackets are the α-deformed ones and are related to the Moyal–Weyl star product. We discuss early- and late-time attractors and reconstruct the cosmological evolution. We show that the model can have the ΛCDM model as a future attractor if we initially consider a massless scalar field without a cosmological constant term.
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SHARIF, M., et ABDUL JAWAD. « INTERACTING GENERALIZED DARK ENERGY AND RECONSTRUCTION OF SCALAR FIELD MODELS ». Modern Physics Letters A 28, no 38 (4 décembre 2013) : 1350180. http://dx.doi.org/10.1142/s0217732313501800.

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In this paper, we consider the interacting generalized dark energy with cold dark matter and analyze the behavior of evolution parameter via dark energy and interacting parameters. It is found that the evolution parameter crosses the phantom divide line in most of the cases of integration constants. We also establish the correspondence of scalar field models (quintessence, k-essence and dilaton) with this dark energy model in which scalar fields show the increasing behavior. The scalar potential corresponds to attractor solutions in quintessence case.
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20

Do, Tuan Q., et Sonnet Hung Q. Nguyen. « Anisotropic power-law inflation in a two-scalar-field model with a mixed kinetic term ». International Journal of Modern Physics D 26, no 07 (février 2017) : 1750072. http://dx.doi.org/10.1142/s0218271817500729.

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We examine whether an extended scenario of a two-scalar-field model, in which a mixed kinetic term of canonical and phantom scalar fields is involved, admits the Bianchi type I metric, which is homogeneous but anisotropic spacetime, as its power-law solutions. Then, we analyze the stability of the anisotropic power-law solutions to see whether these solutions respect the cosmic no-hair conjecture or not during the inflationary phase. In addition, we will also investigate a special scenario, where the pure kinetic terms of canonical and phantom fields disappear altogether in field equations, to test again the validity of cosmic no-hair conjecture. As a result, the cosmic no-hair conjecture always holds in both these scenarios due to the instability of the corresponding anisotropic inflationary solutions.
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ANDRIANOV, ALEXANDER A., FRANCESCO CANNATA, ALEXANDER YU KAMENSHCHIK et DANIELE REGOLI. « PHANTOM COSMOLOGY BASED ON PT SYMMETRY ». International Journal of Modern Physics D 19, no 01 (janvier 2010) : 97–111. http://dx.doi.org/10.1142/s0218271810016269.

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We consider the PT-symmetric flat Friedmann model of two scalar fields with positive kinetic terms. While the potential of one "normal" field is taken real, that of the other field is complex. We study a complex classical solution of the system of the two Klein–Gordon equations together with the Friedmann equation. The solution for the normal field is real, while the solution for the second field is purely imaginary, realizing classically the "phantom" behavior. The energy density and pressure are real and the corresponding geometry is well defined. The Lagrangian for the linear perturbations has the correct potential signs for both the fields so that the problem of stability does not arise. The background dynamics is determined by an effective action including two real fields — one normal and one "phantom." Remarkably, the phantom phase in the cosmological evolution is transient and the Big Rip never occurs. Our model is contrasted with well known quintom models, which also include one normal and one phantom field.
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Shen, You-Gen, et Xian-Hui Ge. « Constructing Phantom With a Nonminimally Coupled Complex Scalar Field ». International Journal of Theoretical Physics 45, no 1 (janvier 2006) : 17–29. http://dx.doi.org/10.1007/s10773-005-9004-0.

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23

Sun, Zu-Yao, et You-Gen Shen. « Phantom cosmology with non-minimally coupled real scalar field ». General Relativity and Gravitation 37, no 1 (janvier 2005) : 243–51. http://dx.doi.org/10.1007/s10714-005-0014-2.

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Granda, L. N., et D. F. Jimenez. « Dynamical analysis for a scalar–tensor model with kinetic and nonminimal couplings ». International Journal of Modern Physics D 27, no 03 (février 2018) : 1850030. http://dx.doi.org/10.1142/s021827181850030x.

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We study the autonomous system for a scalar–tensor model of dark energy with nonminimal coupling to curvature and nonminimal kinetic coupling to the Einstein tensor. The critical points describe important stable asymptotic scenarios including quintessence, phantom and de Sitter attractor solutions. Two functional forms for the coupling functions and the scalar potential were considered: power-law and exponential functions of the scalar field. For power-law couplings, the restrictions on stable quintessence and phantom solutions lead to asymptotic freedom regime for the gravitational interaction. For the exponential functions, the stable quintessence, phantom or de Sitter solutions allow asymptotic behaviors where the effective Newtonian coupling can reach either the asymptotic freedom regime or constant value. The phantom solutions could be realized without appealing to ghost degrees of freedom. Transient inflationary and radiation dominated phases can also be described.
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Kucukakca, Yusuf. « Interacting phantom cosmology via Noether symmetry approach ». International Journal of Geometric Methods in Modern Physics 17, no 12 (19 septembre 2020) : 2050179. http://dx.doi.org/10.1142/s0219887820501790.

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In this paper, we have presented a cosmological model where a phantom scalar field is minimally coupled to dark matter component. Noether symmetry method was applied both to investigate the cosmological solution and to find out what is the form of the potential of scalar field and the unknown function in the considered model. By using this method, these forms are resulted as trigonometric functions. Also, the obtained cosmological solutions are compatible with observations describing the accelerated expansion of the Universe. Furthermore, it turns out that the effective equation of state parameter in the model can cross the phantom divide line.
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RAHAMAN, F., M. KALAM et K. A. RAHMAN. « WORMHOLES SUPPORTED BY SCALAR FIELDS WITH NEGATIVE KINETIC ENERGY ». International Journal of Modern Physics A 24, no 27 (30 octobre 2009) : 5007–18. http://dx.doi.org/10.1142/s0217751x09046023.

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We provide a new model of higher-dimensional wormholes supported by phantom energy derived from a scalar field with negative kinetic term. We have shown that the Averaged Null Energy Condition (ANEC) violating phantom energy can be reduced as desired. We have also noticed that dimension of the space–time plays a crucial role for measuring the ANEC violating matter needed.
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SHCHIGOLEV, V. K., et M. P. ROTOVA. « COSMOLOGICAL MODEL OF INTERACTING TACHYON FIELD ». Modern Physics Letters A 27, no 17 (juin 2012) : 1250086. http://dx.doi.org/10.1142/s0217732312500861.

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In this paper we investigate a tachyon field model in cosmology, provided its interaction with the quintessence or phantom fields. The model takes into account this interaction beyond the usual approach, in which the interaction is phenomenologically described by the energy flow between the matter components. In our model, the interaction of tachyon field with a canonical scalar field is taken into account through the interaction potential in the total Lagrangian of the system, like in the case of two or more canonical scalar fields. We obtain the different types of exact solution for the model by employing the so-called "first order formalism" procedures.
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Oz, I. Basaran, Y. Kucukakca et N. Unal. « Anisotropic solution in phantom cosmology via Noether symmetry approach ». Canadian Journal of Physics 96, no 7 (juillet 2018) : 677–80. http://dx.doi.org/10.1139/cjp-2017-0765.

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In this study, we consider a phantom cosmology in which a scalar field is minimally coupled to gravity. For anisotropic locally rotational symmetric (LRS) Bianchi type I space–time, we use the Noether symmetry approach to determine the potential of such a theory. It is shown that the potential must be in the trigonometric form as a function of the scalar field. We solved the field equations of the theory using the result obtained from the Noether symmetry. Our solution shows that the universe has an accelerating expanding phase.
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SANYAL, ABHIK KUMAR. « INFLATION IS PERHAPS THE GENERIC FEATURE OF PHANTOM FIELD, NOT THE BIG-RIP ». International Journal of Modern Physics A 22, no 07 (20 mars 2007) : 1301–15. http://dx.doi.org/10.1142/s0217751x07035173.

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A class of solutions for phantom field corresponding to a generalized k-essence Lagrangian has been presented, employing a simple method which provides the scope to explore many such. All the solutions having dynamical state parameter are found to touch the magic line w = -1 asymptotically. The solutions with constant equation of state can represent phantom, quitessence or an ordinary scalar field cosmologies depending on the choice of a couple of parameters of the theory. For w ≈ -1, quintessence and phantom models are indistinguishable through the Hubble parameter. Finally, it appears that inflation rather than big-rip is the generic feature of phantom cosmology.
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COLEY, A., S. HERVIK et J. LATTA. « THE PHANTOM OF THE OPRA ». Modern Physics Letters A 21, no 14 (10 mai 2006) : 1099–106. http://dx.doi.org/10.1142/s0217732306020640.

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The Observed Perlmutter-Riess Acceleration (OPRA) implies that the expansion of the Universe is currently increasing and is motivation for the so-called phantom energy models. We consider the dynamics of phantom scalar field models. An important physical time constraint, which can be used to rule out many cosmological models, is obtained from the condition that all forms of energy density, including the field causing OPRA (e.g., the phantom field), must be non-negligible for an extended period, which is conservatively estimated to be of the order of a few Gyr. We find that this physical time constraint cannot be satisfied in conventional phantom cosmological models.
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CHIMENTO, LUIS P., et RUTH LAZKOZ. « UNIFIED PHANTOM COSMOLOGIES ». International Journal of Modern Physics D 14, no 03n04 (avril 2005) : 587–98. http://dx.doi.org/10.1142/s021827180500616x.

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We present a general algorithm based on the concept of form-invariance which can be used for generating phantom cosmologies. It involves linear transformations between the kinetic energy and the potential of the scalar field, and transforms solutions of the Einstein–Klein–Gordon equations which preserve the weak energy condition into others which violate it, while keeping the energy density of the field positive. Several known solutions representing phantom cosmologies are unified by this procedure. Using the general algorithm we obtain those solutions and show the relations between them. In addition, the scale factors of the product and seed solutions are related by a generalization of the well-known a→a-1 duality.
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32

Li, Jin, Kai Lin, Hao Wen et Wei-Liang Qian. « Gravitational Quasinormal Modes of Regular Phantom Black Hole ». Advances in High Energy Physics 2017 (2017) : 1–19. http://dx.doi.org/10.1155/2017/5234214.

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We investigate the gravitational quasinormal modes (QNMs) for a type of regular black hole (BH) known as phantom BH, which is a static self-gravitating solution of a minimally coupled phantom scalar field with a potential. The studies are carried out for three different spacetimes: asymptotically flat, de Sitter (dS), and anti-de Sitter (AdS). In order to consider the standard odd parity and even parity of gravitational perturbations, the corresponding master equations are derived. The QNMs are discussed by evaluating the temporal evolution of the perturbation field which, in turn, provides direct information on the stability of BH spacetime. It is found that in asymptotically flat, dS, and AdS spacetimes the gravitational perturbations have similar characteristics for both odd and even parities. The decay rate of perturbation is strongly dependent on the scale parameterb, which measures the coupling strength between phantom scalar field and the gravity. Furthermore, through the analysis of Hawking radiation, it is shown that the thermodynamics of such regular phantom BH is also influenced byb. The obtained results might shed some light on the quantum interpretation of QNM perturbation.
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33

Sinha, Swati, Surajit Chattopadhyay et Irina Radinschi. « Cosmology of viscous holographic f(G) gravity and consequences in the framework of quintessence scalar field ». International Journal of Geometric Methods in Modern Physics 16, no 11 (novembre 2019) : 1950176. http://dx.doi.org/10.1142/s0219887819501767.

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Work reported in this study demonstrates the reconstruction schemes for the [Formula: see text] gravity in the framework of bulk viscosity and holographic background evolution by considering the universe filled by the viscous fluid that is just special class of more general fluids as described in Nojiri and Odintsov [Inhomogeneous equation of state of the universe: Phantom era, future singularity, and crossing the phantom barrier, Phys. Rev. D 72 (2005) 023003]. The bulk viscous pressure has been considered as [Formula: see text], with [Formula: see text]. Considering the scale factor in power law form and taking holographic dark energy (HDE) with density [Formula: see text] and generalized extended holographic dark energy (EGHRDE) with density [Formula: see text], a specific case of Nojiri–Odintsov holographic DE ([Unifying phantom inflation with late-time acceleration: Scalar phantom–non-phantom transition model and generalized holographic dark energy, Gen. Relativ. Gravit. 38 (2006) 1285]) we have derived solutions for [Formula: see text] and the subsequent effective equation of state parameters have been found to behave like quintom irrespective of the choice of [Formula: see text]. Finally, considering [Formula: see text] as quintessence scalar field we have explored the possibility of quasi-exponential expansion and warm inflation.
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34

Santhi, M. Vijaya, V. U. M. Rao et Y. Aditya. « Kantowski–Sachs scalar field cosmological models in a modified theory of gravity ». Canadian Journal of Physics 95, no 2 (février 2017) : 136–44. http://dx.doi.org/10.1139/cjp-2016-0718.

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In this paper, we investigate the anisotropic Kantowski–Sachs model in the f(R, T) theory of gravity proposed by Harko et al. (Phys. Rev. D, 84, 024020, 2011) with scalar field (quintessence or phantom). Here R is the Ricci scalar and T is the trace of the energy–momentum tensor. The field equations have been solved using the fact that scalar expansion is proportional to the shear scalar of the space–time. We explore the behavior of the deceleration parameter, which represents a transition of the universe from the early decelerating phase to the present accelerated phase. Some physical properties and various cosmological distance measures are also obtained and discussed.
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35

Tuan, Do Quoc, et Nguyen Sonnet Hung Q. « No Small Hairs in Anisotropic Power-law Gauss-Bonnet Inflation ». Communications in Physics 29, no 2 (14 mai 2019) : 173. http://dx.doi.org/10.15625/0868-3166/29/2/13677.

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We will examine whether anisotropic hairs exist in a string-inspired scalar-Gauss-Bonnet gravity model with the absence of potential of scalar field during the inflationary phase. As a result, we are able to obtain the Bianchi type I power-law solution to this model under the assumption that the scalar field acts as the phantom field, whose kinetic is negative definite. However, the obtained anisotropic hair of this model turns out to be large, which is inconsistent with the observational data. We will therefore introduce a nontrivial coupling between scalar and vector fields such as \(f^2(\phi)F_{\mu\nu}F^{\mu\nu}\) into the scalar-Gauss-Bonnet model with the expectation that the anisotropic hair would be reduced to a small one. Unfortunately, the magnitude of the obtained anisotropic hair is still large. These results indicate that the scalar-Gauss-Bonnet gravity model with the absence of potential of scalar field might not be suitable to generate small anisotropic hairs during the inflationary phase.
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36

DZHUNUSHALIEV, VLADIMIR, ILIAS KULNAZAROV et RATBAY MYRZAKULOV. « PHANTOM "RENORMALIZATION" OF MASS OF A QUANTIZED ELECTRIC CHARGE ». Modern Physics Letters A 25, no 36 (30 novembre 2010) : 3017–26. http://dx.doi.org/10.1142/s0217732310034298.

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A regular wormhole solution in gravity coupled with a phantom scalar and electromagnetic fields is found. The solution exists for a special choice of the parameter f of the potential term. The mass m of a wormhole filled with a phantom and electrostatic fields is calculated. It is shown that close to some point f0, a small value of the mass m is the remainder of two large masses of the phantom and electrostatic fields. The connection with the renormalization procedure in quantum filed theory is considered. The connection between Wheeler's idea "mass without mass" and renormalization procedure in quantum field theory is discussed.
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37

Xiao, Kui. « The evolutionary pictures for phantom field in loop quantum cosmology ». International Journal of Modern Physics D 28, no 15 (novembre 2019) : 1950170. http://dx.doi.org/10.1142/s0218271819501700.

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The evolutionary pictures for phantom field in loop quantum cosmology are discussed in this paper. Comparing the dynamical behaviors of the phantom field with one of the canonical scalar fields in loop quantum cosmology scenario, we found that the [Formula: see text] phase trajectories are the same, but the [Formula: see text] phase-spaces are very different, and the phantom field with considering potentials can drive neither super inflation nor slow-roll inflation in loop quantum cosmology (LQC) scenario. While the universe is filled with multiple dark fluids, to ensure that the condition [Formula: see text] does not violate, the energy density of dark matter [Formula: see text] and the equation-of-state of phantom field [Formula: see text] should satisfy the condition [Formula: see text] at the bounce point. If this constraint condition holds, the universe can enter an inflationary stage, and it is possible to unify the description of phantom field, dark matter and inflation. We introduced a toy model which has the same form of the general Chaplygin gas to unify the dark energy, dark matter and slow-roll inflation, and the slow-roll inflation of the toy model has also been discussed.
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38

Kleihaus, Burkhard, Jutta Kunz et Eugen Radu. « Balancing a static black ring with a phantom scalar field ». Physics Letters B 797 (octobre 2019) : 134892. http://dx.doi.org/10.1016/j.physletb.2019.134892.

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39

Jesus, J. F., R. Valentim, A. A. Escobal, S. H. Pereira et D. Benndorf. « Gaussian processes reconstruction of the dark energy potential ». Journal of Cosmology and Astroparticle Physics 2022, no 11 (1 novembre 2022) : 037. http://dx.doi.org/10.1088/1475-7516/2022/11/037.

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Abstract Scalar Fields (SF) have emerged as natural candidates for dark energy as quintessential or phantom fields, as they are the main ingredient of inflation theories. Instead of assuming some form for the scalar field potential, however, this work reconstructs the SF potential directly from observational data, namely, Hubble and SNe Ia data. We show that two popular forms for the SF potentials, namely, the power-law and the quadratic free-field, are compatible with the reconstructions thus obtained, at least for some choices of the priors of the matter density and curvature parameters and for some redshift intervals.
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40

Sanyal, Abhik Kumar. « Smooth Crossing ofwΛ=−1Line in a Single Scalar Field Model ». Advances in High Energy Physics 2009 (2009) : 1–14. http://dx.doi.org/10.1155/2009/612063.

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Smooth double crossing of the phantom divide linewΛ=−1has been found possible with a single minimally coupled scalar field for the most simple form of generalizedk-essence cosmological model, in the presence of background cold dark matter. Such crossing is a sufficiently late time transient phenomenon and does not have any pathological behaviour.
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41

RODGERS, VINCENT G. J., et TAKESHI YASUDA. « GENERAL COORDINATE TRANSFORMATIONS AS THE ORIGINS OF DARK ENERGY ». International Journal of Modern Physics A 22, no 04 (10 février 2007) : 749–76. http://dx.doi.org/10.1142/s0217751x07035100.

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In this note we demonstrate that the algebra associated with coordinate transformations might contain the origins of a scalar field that can behave as an inflaton and/or a source for dark energy. We will call this particular scalar field the diffeomorphism scalar field. In one dimension, the algebra of coordinate transformations is the Virasoro algebra while the algebra of gauge transformations is the Kac–Moody algebra. An interesting representation of these algebras corresponds to certain field theories that have meaning in any dimension. In particular, the so-called Kac–Moody sector corresponds to Yang–Mills theories and the Virasoro sector corresponds to the diffeomorphism field theory that contains the scalar field and a rank-two symmetric, traceless tensor. We will focus on the contributions of the diffeomorphism scalar field to cosmology. We show that this scalar field can, qualitatively, act as a phantom dark energy, an inflaton, a dark matter source, and the cosmological constant Λ.
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42

El-Nabulsi, Rami Ahmad. « Five-dimensional Brans–Dicke compactified universe dominated by a varying speed of light ». Modern Physics Letters A 35, no 30 (6 août 2020) : 2050252. http://dx.doi.org/10.1142/s0217732320502521.

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We extend the model of a 5D Brans–Dicke gravity theory reduced to 4D through the presence of a hypersurface-orthogonal space-like killing vector field in the underlying 5D spacetime by including a varying speed of light. The resulting model is characterized by the presence of two scalar fields. We focus on late-time power law solutions which emerge in general when scalar fields couple to spacetime curvature and do not contradict the SNIa astrophysical data. Analytic solutions in 4-dimensions are derived and late-time accelerated expansion was found. The universe is dominated by dark energy, free from phantom field and is characterized by a decaying energy matter density, decaying scalar fields, and a decreasing celerity of light. The model is confronted with astrophysical observations and is found to fit these data.
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43

DZHUNUSHALIEV, VLADIMIR, VLADIMIR FOLOMEEV, KAIRAT MYRZAKULOV et RATBAY MYRZAKULOV. « PHANTOM FIELDS : BOUNCE SOLUTIONS IN THE EARLY UNIVERSE AND S-BRANES ». International Journal of Modern Physics D 17, no 12 (novembre 2008) : 2351–58. http://dx.doi.org/10.1142/s0218271808013911.

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A cosmological model with two phantom scalar fields with a special choice of the field potential is considered. The obtained regular solution describes a bounce with a subsequent transition to the de Sitter stage of the expansion of the universe. This solution could also be interpreted as an S-brane solution.
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44

Pourhassan, B. « Unified universe history through phantom extended Chaplygin gas ». Canadian Journal of Physics 94, no 7 (juillet 2016) : 659–70. http://dx.doi.org/10.1139/cjp-2016-0154.

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The universe evolution from inflation to late-time acceleration is investigated in a unified way, using a two-component fluid constituted from extended Chaplygin gas alongside a phantom scalar field. We extract solutions for the various cosmological eras, focusing on the behavior of the scale factor, the various density parameters and the equation-of-state parameter. Furthermore, we extract and discuss bouncing solutions. Finally, we examine the perturbations of the model, ensuring their stability and extracting the predictions for the tensor-to-scalar ratio.
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45

Dănilă, Bogdan, Tiberiu Harko, Man Kwong Mak, Praiboon Pantaragphong et Sorin V. Sabau. « Jacobi Stability Analysis of Scalar Field Models with Minimal Coupling to Gravity in a Cosmological Background ». Advances in High Energy Physics 2016 (2016) : 1–26. http://dx.doi.org/10.1155/2016/7521464.

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We study the stability of the cosmological scalar field models by using the Jacobi stability analysis, or the Kosambi-Cartan-Chern (KCC) theory. In this approach, we describe the time evolution of the scalar field cosmologies in geometric terms, by performing a “second geometrization” and considering them as paths of a semispray. By introducing a nonlinear connection and a Berwald-type connection associated with the Friedmann and Klein-Gordon equations, five geometrical invariants can be constructed, with the second invariant giving the Jacobi stability of the cosmological model. We obtain all the relevant geometric quantities, and we formulate the condition for Jacobi stability in scalar field cosmologies. We consider the Jacobi stability properties of the scalar fields with exponential and Higgs type potential. The Universe dominated by a scalar field exponential potential is in Jacobi unstable state, while the cosmological evolution in the presence of Higgs fields has alternating stable and unstable phases. We also investigate the stability of the phantom quintessence and tachyonic scalar field models, by lifting the first-order system to the tangent bundle. It turns out that in the presence of a power law potential both of these models are Jacobi unstable during the entire cosmological evolution.
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Unterberger, Andreas, Andreas Kempf et Khadijeh Mohri. « 3D Evolutionary Reconstruction of Scalar Fields in the Gas-Phase ». Energies 12, no 11 (30 mai 2019) : 2075. http://dx.doi.org/10.3390/en12112075.

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An evolutionary reconstruction technique (ERT) was developed for three-dimensional (3D) reconstruction of luminescent objects, in particular turbulent flames for the first time. The computed tomography (CT) algorithm is comprised of a genetic algorithm (GA) and a ray-tracing software. To guide the reconstruction process, a mask is introduced. It uses a Metropolis algorithm (MA) to sample locations where specific genetic operators can be applied. Based on an extensive parameter study, performed on several types of phantoms, the ability of our algorithm for 3D reconstructions of fields with varying complexities is demonstrated. Furthermore, it was applied to three experiments, to reconstruct the instantaneous chemiluminescence field of a bunsen flame, a highly turbulent swirl flame and the turbulent Cambridge-Sandia stratified flame. Additionally, we show direct and quantitative comparison to an advanced computed tomography of chemiluminescence (CTC) method that is based on an algebraic reconstruction technique (ART). The results showed good agreement between CTC and ERT using both phantom data from flame simulations, and experimental data.
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Chandra Dubey, Vipin, Ambuj Kumar Mishra, Shikha Srivastava et Umesh Kumar Sharma. « Tsallis holographic dark energy models in axially symmetric space time ». International Journal of Geometric Methods in Modern Physics 17, no 01 (janvier 2020) : 2050011. http://dx.doi.org/10.1142/s0219887820500115.

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In this work, we have examined the behavior of Bianchi-I (axially symmetric) matter-dominated and the anisotropic Universe with the proposed dark energy, Tsallis holographic dark energy (THDE), with the Hubble horizon as infrared cut-off [Tavayef et al., Tsallis holographic dark energy, Phys. Lett. B 781 (2018) 195–200]. The Universe evolution from matter-dominated epoch to dark energy dominated epoch is described by our proposed THDE model. The EoS parameter in our THDE model explains the evolution of the Universe according to the value of nonextensive or Tsallis parameter [Formula: see text], phantom era ([Formula: see text]) or quintom (phantom line crossing) and the quintessence era ([Formula: see text]), before reaching to completely dark energy-dominated era in the future. Additionally, we also plan to reconcile the dark energy by the method of reconstructing the evolution of the scalar field potential. For the analysis, we take into account the quintessence field and phantom scalar field for this reconstruction, which at present shows the accelerated expansion.
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GOGBERASHVILI, MERAB, PAVLE MIDODASHVILI et LEVAN MIDODASHVILI. « LOCALIZATION PROBLEM IN THE 5D STANDING WAVE BRANEWORLD ». International Journal of Modern Physics D 21, no 10 (octobre 2012) : 1250081. http://dx.doi.org/10.1142/s0218271812500812.

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We investigate the problem of pure gravitational localization of matter fields within the 5D standing wave braneworld generated by gravity coupled to a phantom-like scalar field. We show that in the case of increasing warp factor there exist normalizable zero modes of spin-0, -1/2, -1 and -2 fields on the brane.
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49

CANNATA, FRANCESCO, et ALEXANDER Y. KAMENSHCHIK. « CHAMELEON COSMOLOGY MODEL DESCRIBING THE PHANTOM DIVIDE LINE CROSSING ». International Journal of Modern Physics D 20, no 02 (février 2011) : 121–31. http://dx.doi.org/10.1142/s0218271811018755.

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An exact solution describing the evolution of the type Bang-to-Rip with the phantom divide line crossing is constructed in the chameleon cosmology model, based on two independent functions of the scalar field.
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Fermi, Davide, Massimo Gengo et Livio Pizzocchero. « On the Necessity of Phantom Fields for Solving the Horizon Problem in Scalar Cosmologies ». Universe 5, no 3 (11 mars 2019) : 76. http://dx.doi.org/10.3390/universe5030076.

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We discuss the particle horizon problem in the framework of spatially homogeneous and isotropic scalar cosmologies. To this purpose we consider a Friedmann–Lemaître–Robertson–Walker (FLRW) spacetime with possibly non-zero spatial sectional curvature (and arbitrary dimension), and assume that the content of the universe is a family of perfect fluids, plus a scalar field that can be a quintessence or a phantom (depending on the sign of the kinetic part in its action functional). We show that the occurrence of a particle horizon is unavoidable if the field is a quintessence, the spatial curvature is non-positive and the usual energy conditions are fulfilled by the perfect fluids. As a partial converse, we present three solvable models where a phantom is present in addition to a perfect fluid, and no particle horizon appears.
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