scholarly journals Realization of blue spectrum in generalized Galileon super-inflation models

2017 ◽  
Vol 26 (03) ◽  
pp. 1750016
Author(s):  
K. Nozari ◽  
S. Shafizadeh
Keyword(s):  
Tensor Perturbation

In the spirit of Galileon inflation and by considering some sorts of noncanonical kinetic terms in the action, we realize a stage of super-inflation leading to a blue-tilted tensor perturbation. We show also that addition of Galileon-like term to the action leads to avoidance of ghost instabilities in this setup.

scholarly journals Beginning of Universe through large field hybrid inflation

2015 ◽  
Vol 30 (21) ◽  
pp. 1550106 ◽  
Author(s):  
Tatsuo Kobayashi ◽  
Osamu Seto
Keyword(s):  
Gravitational Wave ◽  
Early Universe ◽  
High Energy ◽  
Wave Mode ◽  
Energy Scale ◽  
Large Field ◽  
Tensor Perturbation ◽  
Expectation Value ◽  
Hybrid Inflation ◽  
High Energy Scale

Recent detection of B-mode polarization induced from tensor perturbations by the BICEP2 experiment implies the so-called large field inflation, where an inflaton field takes super-Planckian expectation value during inflation, at a high energy scale. We show however, if another inflation follows hybrid inflation, the hybrid inflation can generate a large tensor perturbation with not super-Planckian but Planckian field value. This scenario would relax the tension between BICEP2 and Planck concerning the tensor-to-scalar ratio, because a negative large running can also be obtained for a certain number of e-fold of the hybrid inflation. A natural interpretation of a large gravitational wave mode with or without the scalar spectral running might be multiple inflation in the early Universe.

Cartesian Tensor Perturbation Scheme for the Senftleben Effect

1971 ◽  
Vol 54 (1) ◽  
pp. 223-234 ◽  
Author(s):  
E. R. Cooper ◽  
D. K. Hoffman
Keyword(s):  
Perturbation Scheme ◽  
Tensor Perturbation

scholarly journals Spontaneous Symmetry Breaking in 5D Conformally Invariant Gravity

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Taeyoon Moon ◽  
Phillial Oh
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Conformal Symmetry ◽  
Brane World ◽  
Spontaneous Breaking ◽  
Warp Factor ◽  
Translational Symmetry ◽  
Tensor Perturbation ◽  
Conformally Invariant ◽  
Conformal Quantum Mechanics

We explore the possibility of the spontaneous symmetry breaking in 5D conformally invariant gravity, whose action consists of a scalar field nonminimally coupled to the curvature with its potential. Performing dimensional reduction via ADM decomposition, we find that the model allows an exact solution giving rise to the 4D Minkowski vacuum. Exploiting the conformal invariance with Gaussian warp factor, we show that it also admits a solution which implements the spontaneous breaking of conformal symmetry. We investigate its stability by performing the tensor perturbation and find the resulting system is described by the conformal quantum mechanics. Possible applications to the spontaneous symmetry breaking of time-translational symmetry along the dynamical fifth direction and the brane-world scenario are discussed.

Inflation with a constant ratio of scalar and tensor perturbation amplitudes

2002 ◽  
Vol 65 (8) ◽  
Author(s):  
César A. Terrero-Escalante ◽  
James E. Lidsey ◽  
Alberto A. García
Keyword(s):  
Constant Ratio ◽  
Tensor Perturbation

scholarly journals Consistent scalar and tensor perturbation power spectra in single fluid matter bounce with dark energy era

2018 ◽  
Vol 97 (8) ◽  
Author(s):  
Anna Paula Bacalhau ◽  
Nelson Pinto-Neto ◽  
Sandro Dias Pinto Vitenti
Keyword(s):  
Dark Energy ◽  
Power Spectra ◽  
Tensor Perturbation ◽  
Fluid Matter

Birth of the inflationary Universe and tensor fluctuations

2016 ◽  
Vol 25 (13) ◽  
pp. 1645009
Author(s):  
Jun’ichi Yokoyama
Keyword(s):  
Inflationary Universe ◽  
Full Understanding ◽  
Tensor Perturbation

In order to achieve full understanding of our Universe, we wish to clarify how it was created. In this talk, I discussed several possibilities and relevance to the observation of tensor perturbation.

scholarly journals Thick braneworld model in nonmetricity formulation of general relativity and its stability

2021 ◽  
Vol 81 (10) ◽  
Author(s):  
Qi-Ming Fu ◽  
Li Zhao ◽  
Qun-Ying Xie
Keyword(s):  
General Relativity ◽  
Order Differential Equation ◽  
Zero Mode ◽  
Gravitational Interaction ◽  
Newtonian Potential ◽  
Special Choice ◽  
Tensor Perturbation ◽  
First Order ◽  
The Stability ◽  
Kaluza Klein

AbstractIn this paper, we study the thick brane system in the so-called f(Q) gravity, where the gravitational interaction was encoded by the nonmetricity Q like scalar curvature R in general relativity. With a special choice of $$f(Q)=Q-b Q^n$$ f ( Q ) = Q - b Q n , we find that the thick brane system can be solved analytically with the first-order formalism, where the complicated second-order differential equation is transformed to several first-order differential equations. Moreover, the stability of the thick brane system under tensor perturbation is also investigated. It is shown that the tachyonic states are absent and the graviton zero mode can be localized on the brane. Thus, the four-dimensional Newtonian potential can be recovered at low energy. Besides, the corrections of the massive graviton Kaluza–Klein modes to the Newtonian potential are also analyzed briefly.

scholarly journals Thick branes with inner structure in mimetic f(R) gravity

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
Jing Chen ◽  
Wen-Di Guo ◽  
Yu-Xiao Liu
Keyword(s):  
Scalar Field ◽  
Effective Potential ◽  
Zero Mode ◽  
Newtonian Gravity ◽  
Tensor Perturbation ◽  
Brane Model ◽  
New Phenomena ◽  
Thick Branes

AbstractIn this paper, we study the structure and gravitational resonances of thick branes generated by a mimetic scalar field in f(R) gravity. We obtain several typical thick brane solutions for $$f(R)=R+\alpha R^2$$ f ( R ) = R + α R 2 . To study their stability, we analyze the tensor perturbation of the metric. It is shown that any thick brane model with $$df/dR>0$$ d f / d R > 0 is stable and the graviton zero mode can be localized on the brane for each solution, which indicates that the four-dimensional Newtonian gravity can be restored. The effect of the parameter $$\alpha $$ α on the gravitational resonances is studied. As a brane splits into multi sub-branes, the effective potential of the tensor perturbation will have an abundant inner structure with multi-wells, and this will lead to new phenomena of the gravitational resonances.

scholarly journals Shift-symmetric 𝖲𝖮(𝖭) multi-Galileon

2021 ◽  
Vol 2021 (12) ◽  
pp. 045
Author(s):  
Katsuki Aoki ◽  
Yusuke Manita ◽  
Shinji Mukohyama
Keyword(s):  
Field Theory ◽  
Mass Term ◽  
Equation Of Motion ◽  
Coupling Constants ◽  
Tensor Perturbation ◽  
Four Dimensions ◽  
Field Extensions ◽  
New Type ◽  
Derivatives Of ◽  
Covariant Version

Abstract A Poincarè invariant, local scalar field theory in which the Lagrangian and the equation of motion contain only up to second-order derivatives of the fields is called generalized Galileon. The covariant version of it in four dimensions is called Horndeski theory, and has been vigorously studied in applications to inflation and dark energy. In this paper, we study a class of multi-field extensions of the generalized Galileon theory. By imposing shift and SO(N) symmetries on all the currently known multi-Galileon terms in general dimensions, we find that the structure of the Lagrangian is uniquely determined and parameterized by a series of coupling constants. We also study tensor perturbation in the shift-symmetric SO(3) multi-Galileon theory in four dimensions. The tensor perturbations can obtain a mass term stemming from the same symmetry breaking pattern as the solid inflation. We also find that the shift-symmetric SO(3) multi-Galileon theory gives rise to new cubic interactions of the tensor modes, suggesting the existence of a new type of tensor primordial non-Gaussianity.

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