Thick branes with inner structure in mimetic gravity

Zhong, Yi; Zhong, Yuan; Zhang, Yupeng; Liu, Yu-Xiao

doi:10.1140/epjc/s10052-018-5527-4

Cited by 33 publications

(39 citation statements)

References 75 publications

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“…In this section, we briefly introduce the mimetic thick brane model and the linear perturbation of the brane system, which were given in Ref. [61] in detail. We take the geometrized units in which the gravitational constant κ 2 = 1.…”

Section: Linear Perturbation In a Mimetic Thick Brane Modelmentioning

confidence: 99%

“…In this work, the mimetic scalar field φ = φ(y) is used to generate the thick brane. Therefore, we assume that U (φ) = g M N ∂ M φ∂ N φ > 0 [61]. This generalization can also provide thick branes with inner structure.…”

Section: Linear Perturbation In a Mimetic Thick Brane Modelmentioning

confidence: 99%

“…This generalization can also provide thick branes with inner structure. The equations of motion can be easily obtained by varying the action with respect to the physical metric g M N , the mimetic scalar field φ and the Lagrange multiplier λ [61]:…”

Section: Linear Perturbation In a Mimetic Thick Brane Modelmentioning

confidence: 99%

“…Later, thick branes with inner structure generated by mimetic scalar field were found in Ref. [61]. The gravitational perturbation was analyzed in detail.…”

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confidence: 99%

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Gravitational resonances in mimetic thick branes

Zhong

Zhang

Guo

et al. 2019

J. High Energ. Phys.

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In this work, we investigate gravitational resonances in both single and double mimetic thick branes, which can provide a new way to detect the extra dimension. For the single brane model, we apply the relative probability proposed in [Phys. Rev. D. 80 (2009) 065019]. For the double brane model, we investigate the resonances quasi-localized on the double brane, on the sub-branes and between the sub-branes, respectively. To investigate the resonances quasi-localized on the double brane, we introduce two different definitions of the relative probability and find that the corresponding mass spectra of gravitational resonances are almost the same. For the gravitational resonances quasi-localized on subbranes and between the sub-branes, the influence of the distance between the two subbranes and the thickness of the sub-branes are analyzed and new features are found in both cases.

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Section: Linear Perturbation In a Mimetic Thick Brane Modelmentioning

confidence: 99%

Section: Linear Perturbation In a Mimetic Thick Brane Modelmentioning

confidence: 99%

Section: Linear Perturbation In a Mimetic Thick Brane Modelmentioning

confidence: 99%

“…Later, thick branes with inner structure generated by mimetic scalar field were found in Ref. [61]. The gravitational perturbation was analyzed in detail.…”

mentioning

confidence: 99%

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Gravitational resonances in mimetic thick branes

Zhong

Zhang

Guo

et al. 2019

J. High Energ. Phys.

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“…However, the HD terms in general make the theory susceptible to Ostrogradsky ghost or(and) gradient instabilities [26,27,[64][65][66][67], possible wayouts of which point to more complicated extensions of the CM model. For instance, one may require to incorporate explicit HD couplings with the Ricci curvature scalar R [66-69], or resort to degenerate higher-order scalar-tensor (DHOST) Lagrangians [70,71].Noteworthy mimetic extensions from various other considerations include the mimetic f (R) gravity and its unimodular, non-local and several more variants [15,[36][37][38][39][40][41][42][72][73][74][75], mimetic Horndeski theory [76,77], mimetic Born-Infeld theory [78,79], mimetic brane-world gravity [80][81][82], mimetic massive gravity [83][84][85][86], and so on [87][88][89][90][91]. Interestingly, it has also been shown that mimetic gravity has a close correspondence with the scalar version of the Einstein-AEther theory, and hence appears in the infrared limit of the projectable Hořava-Lifshiftz gravity [94][95][96][97][98]…”

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confidence: 99%

Cosmological dark sector from a mimetic–metric–torsion perspective

Chothe

Dutta

Sur

2019

Int. J. Mod. Phys. D

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We generalize the basic theory of mimetic gravity by extending its purview to the general metriccompatible geometries that admit torsion, in addition to curvature. This essentially implies reinstating the mimetic principle of isolating the conformal degree of freedom of gravity in presence of torsion, by parametrizing both the physical metric and torsion in terms of the scalar 'mimetic' field and the metric and torsion of a fiducial space. We assert the requisite torsion parametrization from an inspection of the fiducial space Cartan transformation which, together with the conformal transformation of the fiducial metric, preserve the physical metric and torsion. In formulating the scalar-tensor equivalent Lagrangian, we consider an explicit contact coupling of the mimetic field with torsion, so that the former can manifest itself geometrically as the source of a torsion mode, and most importantly, give rise to a viable 'dark universe' picture from a mimicry of an evolving dust-like cosmological fluid with a non-zero pressure. A further consideration of higher derivatives of the mimetic field in the Lagrangian leads to physical bounds on the mimetic-torsion coupling strength, which we determine explicitly. * transformation of g µν , but also implicates that φ is left non-dynamical by the condition for the invertibility of g µν , viz. −κ 2 g µν ∂ µ φ∂ ν φ = 1 . This condition could be implemented in the theory as a constraint, using a Lagrange multiplier λ in an equivalent mimetic action. A further equivalence of the latter with the singular Brans-Dicke (BD) action (in which the BD parameter w = − 3 2 ) eventually shows that mimetic gravity is indeed a ratification of GR being raised to the status of a scalar-tensor equivalent MG theory [21][22][23][24]29].Detailed studies have revealed many attractive features of the basic mimetic model of Chemseddine and Mukhanov (henceforth, the CM model [21]) and its various extensions, from the perspectives of both cosmology and astrophysics . In particular, the CM Lagrangian extended by a potential V (φ) leads to the scenarios of a cosmologically evolving fluid -the so-called 'mimetic fluid' -which characterizes dust, albeit with a nonvanishing pressure 1 [22]. As such, no propagating scalar perturbation mode is there to suppress the growth of structures at smaller (sub-galactic) scales [26,27]. Nor it is possible to define the quantum fluctuations to the (non-dynamical) field φ, so that the latter can provide the seeds of the observed large scale structure of the universe [22,23]. A reasonable supposition has therefore been to extend the CM theory further by incorporating higher derivative (HD) term(s) for φ, e.g. (✷φ) 2 , which lead(s) to a non-vanishing sound speed c s of the mimetic matter perturbations, keeping the background solution unaffected qualitatively 2 [22,23,29]. However, the HD terms in general make the theory susceptible to Ostrogradsky ghost or(and) gradient instabilities [26,27,[64][65][66][67], possible wayouts of which point to more complicated extensions...

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U(1) gauge vector field on a codimension-2 brane

Zhong

Liu

2019

J. High Energ. Phys.

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In this paper, we obtain a gauge invariant effective action for a bulk massless U (1) gauge vector field on a brane with codimension two by using a general Kaluza-Klein (KK) decomposition for the field. It suggests that there exist two types of scalar KK modes to keep the gauge invariance of the action for the massive vector KK modes. Both the vector and scalar KK modes can be massive. The masses of the vector KK modes m (n) contain two parts, m (n) 1 and m (n) 2 , due to the existence of the two extra dimensions. The masses of the two types of scalar KK modes m (n) φ and m (n) ϕ are related to the vector ones, i.e., m (n) φ = m (n) 1 and m (n) ϕ = m (n)2 . Moreover, we derive two Schrödinger-like equations for the vector KK modes, for which the effective potentials are just the functions of the warp factor.

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Thick branes with inner structure in mimetic gravity

Cited by 33 publications

References 75 publications

Gravitational resonances in mimetic thick branes

Gravitational resonances in mimetic thick branes

Cosmological dark sector from a mimetic–metric–torsion perspective

U(1) gauge vector field on a codimension-2 brane

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