Many Faces of Mimetic Gravity

Hammer, Katrin; Vikman, Alexander

doi:10.48550/arxiv.1512.09118

Cited by 36 publications

(52 citation statements)

References 22 publications

(36 reference statements)

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“…The mass scale M is introduced to keep the canonical dimensions of the noncanonical scalar field ϕ. This action (2.1) also naturally appears [7][8][9] in the so-called mimetic gravity [10,11]. For later it is useful to note that the mass scale M can be assumed to be a function of the field ϕ, so that one can allow for a function…”

Section: Modelmentioning

confidence: 99%

Superconducting Dark Matter

Vikman¹

2017

Preprint

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We extend recently proposed mimetic dark matter (DM) and dust of dark energy (DE) models to a U(1)-charged gauged scalar field. This extension yields a mass to the photon via the Higgs mechanism. The square of this photon mass is proportional to the DM energy density. Thus dense DM environments can screen the dark vector force. There is a substantial freedom in this gauged extension of the irrotational fluid-like DM. This freedom enables one to model the classical London equation of superconductivity or to obtain the photon mass which remains constant during the matter-dominated époque.

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Section: Modelmentioning

confidence: 99%

Superconducting Dark Matter

Vikman¹

2017

Preprint

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“…[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36], for recent developments in mimetic gravity see Refs. [37][38][39][40][41][42][43], for the Hamiltonian analysis of mimetic gravity see Refs. [44][45][46], and for a review see Ref.…”

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confidence: 99%

Hamiltonian analysis of Mimetic gravity with higher derivatives

Zheng

2018

Preprint

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Two kinds of mimetic gravity model with higher derivatives of the mimetic field are analyzed in the Hamiltonian formalism. We first perform the Hamiltonian analysis for the mimetic gravity with a general higher derivative function and show the degrees of freedom (DOFs) is 3 which is consistent with the previous result of the Hamiltonian analysis at the perturbation level. We then perform the Hamiltonian analysis for the extended mimetic gravity with higher derivatives directly couples to the Ricci scalar in both Einstein frame and Jordan frame, and we show that different from our previous research at the cosmological perturbation level where only 3 propagating DOFs show up, this generalized mimetic model in general has 4 DOFs. To solve this discrepancy, we find out that the DOFs is reduced to 3 in the unitary gauge while the extra mode is eliminated by appropriate boundary conditions (homogeneous scalar field profile). What makes the system so special is that the Dirac matrix becomes singular in the special unitary gauge, generating extra secondary constraints and reducing the number of DOFs, so we give a similar but simpler example to illustrate how gauge choice affects the number of secondary constraints and the DOFs when the rank of the Dirac matrix is gauge dependent.

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“…Now we can follow a similar procedure as in [26] and [13] and promote the scalar ϕ to an independent dynamical variable in order to eliminate the higher derivatives from the action. On this path we introduce a Lagrange multiplier, λ, enforcing the definition (2.19) so that the action (2.18) transforms into…”

Section: Gauge Invariant Variables and Scalar-vector-tensor Formulationmentioning

confidence: 99%

Axionic cosmological constant

Hammer,

Jirousek,

Vikman

2020

Preprint

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We propose a novel higher-derivative, Weyl-invariant and generally-covariant theory for the cosmological constant. This theory is a mimetic construction with gauge fields playing the role of dynamical variables. These fields compose Chern-Simons current instead of the vector field in the Henneaux and Teitelboim formulation of the unimodular gravity. The equations of motion exactly reproduce the traceless Einstein equations. We demonstrate that, reformulated in Weyl-invariant variables, this novel theory reduces to standard general relativity with the cosmological constant as a Lagrange multiplier. This Lagrange multiplier has an axion-like coupling.

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Many Faces of Mimetic Gravity

Cited by 36 publications

References 22 publications

Superconducting Dark Matter

Superconducting Dark Matter

Hamiltonian analysis of Mimetic gravity with higher derivatives

Axionic cosmological constant

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