scholarly journals BRANE COSMOLOGY WITH A BULK SCALAR FIELD

2002 ◽  
Vol 17 (20) ◽  
pp. 2774-2774
Author(s):  
M. RODRÍGUEZ-MARTÍNEZ
Keyword(s):  
Scalar Field ◽  
Friedmann Equation ◽  
Analytic Solutions ◽  
Scale Factor ◽  
Cosmological Evolution ◽  
World Sheet ◽  
Brane Cosmology ◽  
Static Solutions ◽  
Bulk Scalar Field ◽  
Bulk Scale

In the last few years, brane cosmological models with extra dimensions have been actively studied. In these scenarios, ordinary matter is confined in a (3+1)-dimensional surface (the world-sheet of a 3-brane) while gravity lives in the bulk space-time2,3. In this regard, it has been shown that the cosmology of such models is characterized by a non standard Friedmann equation4,5. Some analytic solutions have been found when the scalar field couples to the brane6, but they correspond to static solutions where the cosmological evolution is due to the motion of the brane into the bulk. In this talk I have presented two kinds of exact solutions obtained by solving Einstein's equations in the light-cone coordinate system and making two different assumptions : a. proportionality between the scalar field and the logarithm of the bulk scale factor7 and b. separable solutions. It has been shown that the first kind of solutions correspond to moving branes into static backgrounds : somehow the hypothesis of proportionality froze the evolution of the metric. On the contrary, in the second kind of solution the bulk is really dynamic. The induced cosmology in the brane has been explored for both types of solutions, confirming, in particular, the non standard cosmological evolution of the scale factor.

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.

The backreaction of massive scalar field on FLRW and de Sitter spaces

2020 ◽  
Vol 17 (03) ◽  
pp. 2050033
Author(s):  
M. R. Setare ◽  
M. Sahraee
Keyword(s):  
Scalar Field ◽  
Energy Momentum Tensor ◽  
Friedmann Equation ◽  
Vacuum Expectation ◽  
Momentum Tensor ◽  
Scale Factor ◽  
Massive Scalar ◽  
De Sitter ◽  
Massive Scalar Field ◽  
Quantum Energy

In this paper, we obtain the effect of backreaction on the scale factor of the Friedmann–Lemaître–Robertson–Walker (FLRW) and de Sitter spaces. We consider a non-minimally coupled massive scalar field to the curvature scalar. For our purpose, we use the results of vacuum expectation values of energy–momentum tensor, which have been obtained previously. By substituting the quantum energy density into the Friedmann equation, we obtain the linear order perturbation of the scale factor. So, the effect of backreaction leads to the new scale factor.

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.

A cosmological exact solution of generalized Brans-Dicke theory with complex scalar field and its phenomenological implications

Open Physics ◽  
2011 ◽  
Vol 9 (6) ◽  
Author(s):  
Metin Arık ◽  
Mehmet Çalık ◽  
Nihan Katırcı
Keyword(s):  
Exact Solution ◽  
Dark Energy ◽  
Scalar Field ◽  
Friedmann Equation ◽  
Constant Term ◽  
Scale Factor ◽  
Complex Scalar ◽  
Complex Scalar Field

AbstractWhen the Brans-Dicke theory is formulated in terms of the Jordan scalar field φ, the amount of dark energy is related to the mass of this field. We investigate a solution which is relevant to the late universe. We show that if φ is taken to be a complex scalar field, then an exact solution to the vacuum equations requires that the Friedmann equation possesses both a constant term and one which is proportional to the inverse sixth power of the scale factor. Possible interpretations and phenomenological implications of this result are discussed.

scholarly journals Kaluza-Klein brane cosmology with a bulk scalar field

2011 ◽  
Vol 84 (4) ◽  
Author(s):  
Arianto ◽  
F. P. Zen ◽  
S. Feranie ◽  
I. P. Widyatmika ◽  
B. E. Gunara
Keyword(s):  
Scalar Field ◽  
Brane Cosmology ◽  
Bulk Scalar Field ◽  
Kaluza Klein

scholarly journals Static solutions for brane models with a bulk scalar field

2000 ◽  
Vol 481 (2-4) ◽  
pp. 386-396 ◽  
Author(s):  
Panagiota Kanti ◽  
Keith A. Olive ◽  
Maxim Pospelov
Keyword(s):  
Scalar Field ◽  
Static Solutions ◽  
Bulk Scalar Field ◽  
Brane Models

scholarly journals Brane cosmology with a bulk scalar field

2001 ◽  
Vol 64 (12) ◽  
Author(s):  
David Langlois ◽  
María Rodríguez-Martínez
Keyword(s):  
Scalar Field ◽  
Brane Cosmology ◽  
Bulk Scalar Field

scholarly journals Reaffirmation of cosmological oscillations in the scale factor from the Pantheon compilation of 1048 Type Ia supernovae

2020 ◽  
Vol 494 (2) ◽  
pp. 2158-2165 ◽  
Author(s):  
H I Ringermacher ◽  
L R Mead
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Energy Density ◽  
Friedmann Equation ◽  
Scale Factor ◽  
Field Energy ◽  
Type Ia Supernovae ◽  
Density Parameter ◽  
Type Ia ◽  
Ia Supernovae

ABSTRACT We observe damped temporal oscillations in the scale factor at a dominant frequency of ∼7 cycles/Hubble-time in the Pantheon compilation of 1048 Type Ia supernovae (SNe Ia). The residual oscillations observed in the Pantheon data closely match and reaffirm our initial observation of oscillations from earlier SNe data (primarily SNLS3 data of Conley 2011) at 2σ confidence. The nearly identical shapes in amplitude, frequency, phase, and damping constant makes it highly likely that the signal is real. Furthermore, two-thirds of the Pantheon SNe cover different portions of the sky compared with SNLS3 strengthening this conclusion. Our model describing the oscillation, presented in an earlier paper, is a simple scalar field harmonic oscillator coupled to the Lambda cold dark matter (ΛCDM) Friedmann equation, but carried into the present epoch. The scalar field energy density plays the role of the dark matter energy density in ΛCDM cosmology, fits well as an average, and closely matches the present dark matter density parameter, suggesting the oscillation plays a role in the dark matter sector. Temporal oscillations in the scale factor and its derivative, as described in this work, would also induce temporal oscillations of the Hubble parameter.

scholarly journals Brane cosmology with a non-minimally coupled bulk-scalar field

2007 ◽  
Vol 24 (14) ◽  
pp. 3701-3712 ◽  
Author(s):  
C Bogdanos ◽  
A Dimitriadis ◽  
K Tamvakis
Keyword(s):  
Scalar Field ◽  
Brane Cosmology ◽  
Bulk Scalar Field

scholarly journals SELF-TUNING DARK ENERGY IN BRANE WORLD COSMOLOGY

2001 ◽  
Vol 16 (17) ◽  
pp. 1089-1099 ◽  
Author(s):  
KUNIHITO UZAWA ◽  
JIRO SODA
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Vacuum Energy ◽  
Friedmann Equation ◽  
Brane World ◽  
Tuning Mechanism ◽  
Enormous Amount ◽  
Self Tuning ◽  
Bulk Scalar Field

In this letter, the self-tuning mechanism of dark energy is proposed by considering the cosmological matter in the brane world. In the first part of this letter, the effective four-dimensional Friedmann equation in the presence of the bulk scalar field is derived. In our model, the bulk scalar field takes the role of the dark energy and its value is slowly varying in time. The claim is that, even if the enormous amount of vacuum energy exists on the brane, the present value of the dark energy is self-tuned to be consistent with the current observations. This result will open the possibility to discuss the dark energy in the brane world in the context of the anthropic principle or quantum cosmology.

Sign in / Sign up

Export Citation Format

Share Document