Braneworld mimetic f(R) gravity

2019 ◽  
Vol 16 (03) ◽  
pp. 1950042 ◽  
Author(s):  
Kourosh Nozari ◽  
Naser Sadeghnezhad
Keyword(s):  
Scalar Field ◽  
Recent Work ◽  
Friedmann Equation ◽  
Equation Of Motion ◽  
Einstein’S Field Equations ◽  
Field Equations ◽  
Einstein's Field Equations ◽  
Bulk Scalar Field ◽  
Codazzi Equations ◽  
Mimetic Gravity

Following our recent work on braneworld mimetic gravity, in this paper, we study an extension of braneworld mimetic gravity to the case that the gravitational sector on the brane is modified in the spirit of [Formula: see text] theories. We assume the physical 5D bulk metric in the Randall–Sundrum II braneworld scenario consists of a 5D scalar field (which mimics the dark sectors on the brane) and an auxiliary 5D metric. We find the 5D Einstein’s field equations and the 5D equation of motion of the bulk scalar field in this setup. By using the Gauss–Codazzi equations, we obtain the induced Einstein’s field equations on the brane. Finally, by adopting the FRW background, we find the Friedmann equation on the brane in this [Formula: see text] mimetic braneworld setup.

scholarly journals ON SIGNATURE TRANSITION IN ROBERTSON–WALKER COSMOLOGIES

2000 ◽  
Vol 15 (10) ◽  
pp. 1521-1531 ◽  
Author(s):  
K. GHAFOORI-TABRIZI ◽  
S. S. GOUSHEH ◽  
H. R. SEPANGI
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Upper Bound ◽  
Classical Model ◽  
Space Time ◽  
Scale Factor ◽  
Einstein’S Field Equations ◽  
Field Equations ◽  
Lorentzian Space ◽  
Einstein's Field Equations

We analyze a classical model of gravitation coupled to a self-interacting scalar field. We show that, within the context of this model for Robertson–Walker cosmologies, there exist solutions in the spatially non-flat cases exhibiting transitions from a Euclidean to a Lorentzian space–time. We then discuss the conditions under which these signature changing solutions to Einstein's field equations exist. In particular, we find that an upper bound for the cosmological constant exists and that close to the signature changing hypersurface, both the scale factor and the scalar field have to be constant. Moreover we find that the signature changing solutions do not exist when the scalar field is massless.

scholarly journals CHAOTIC INFLATION ON THE RANDALL–SUNDRUM TWO-BRANE MODEL

2010 ◽  
Vol 25 (31) ◽  
pp. 2697-2713
Author(s):  
KOUROSH NOZARI ◽  
SIAMAK AKHSHABI
Keyword(s):  
Scalar Field ◽  
Field Potential ◽  
Friedmann Equation ◽  
Warp Factor ◽  
Model Parameters ◽  
Stabilization Mechanism ◽  
Brane Model ◽  
Inflation Model ◽  
Bulk Scalar Field ◽  
Chaotic Inflation

We construct an inflation model on the Randall–Sundrum I (RSI) brane where a bulk scalar field stabilizes the inter-brane separation. We study impact of the bulk scalar field on the inflationary dynamics on the brane. We proceed in two different approaches: in the first approach, the stabilizing field potential is directly appeared in the Friedmann equation and the resulting scenario is effectively a two-field inflation. In the second approach, the stabilization mechanism is considered in the context of a warp factor so that there is just one field present that plays the roles of both inflaton and stabilizer. We study constraints imposed on the model parameters from recent observations.

A brief survey of general relativity

2019 ◽  
pp. 25-50
Author(s):  
Nils Andersson
Keyword(s):  
General Relativity ◽  
Geometric Theory ◽  
Einstein’S Field Equations ◽  
Curved Spacetime ◽  
Field Equations ◽  
Einstein's Field Equations ◽  
Theory Of Gravity

This chapter provides an overview of Einstein’s geometric theory of gravity – general relativity. It introduces the mathematics required to model the motion of objects in a curved spacetime and provides an intuitive derivation of Einstein’s field equations.

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