scholarly journals Covariant and gauge-invariant linear scalar perturbations in multiple scalar field cosmologies

2014 ◽  
Vol 90 (4) ◽  
Author(s):  
Artur Alho ◽  
Filipe C. Mena
Keyword(s):  
Scalar Field ◽  
Gauge Invariant ◽  
Linear Scalar ◽  
Scalar Perturbations

scholarly journals A cosmic microscope for the preheating era

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
JiJi Fan ◽  
Zhong-Zhi Xianyu
Keyword(s):  
Scalar Field ◽  
Nonlinear Effect ◽  
Large Scale ◽  
Nonlinear Effects ◽  
Light Fields ◽  
Unique Probe ◽  
Light Scalar ◽  
Spatially Varying ◽  
Near Future ◽  
Scalar Perturbations

Abstract Light fields with spatially varying backgrounds can modulate cosmic preheating, and imprint the nonlinear effects of preheating dynamics at tiny scales on large scale fluctuations. This provides us a unique probe into the preheating era which we dub the “cosmic microscope”. We identify a distinctive effect of preheating on scalar perturbations that turns the Gaussian primordial fluctuations of a light scalar field into square waves, like a diode. The effect manifests itself as local non-Gaussianity. We present a model, “modulated partial preheating”, where this nonlinear effect is consistent with current observations and can be reached by near future cosmic probes.

scholarly journals COSMOLOGY IN NONLINEAR BORN–INFELD SCALAR FIELD THEORY WITH NEGATIVE POTENTIALS

2007 ◽  
Vol 22 (12) ◽  
pp. 2173-2195 ◽  
Author(s):  
WEI FANG ◽  
H. Q. LU ◽  
Z. G. HUANG
Keyword(s):  
Field Theory ◽  
Scalar Field ◽  
Upper Bound ◽  
Expanding Universe ◽  
Scalar Field Theory ◽  
Stiff Matter ◽  
Ordinary Matter ◽  
Cosmological Solutions ◽  
Potential Parameters ◽  
Linear Scalar

The cosmological evolution in Nonlinear Born–Infeld (hereafter NLBI) scalar field theory with negative potentials was investigated. The cosmological solutions in some important evolutive epoches were obtained. The different evolutional behaviors between NLBI and linear (canonical) scalar field theory have been presented. A notable characteristic is that NLBI scalar field behaves as ordinary matter nearly the singularity while the linear scalar field behaves as "stiff" matter. We find that in order to accommodate current observational accelerating expanding universe the value of potential parameters |m| and |V0| must have an upper bound. We compare different cosmological evolutions for different potential parameters m, V0.

POWER-LOW EXPANSION IN k-ESSENCE COSMOLOGY

2004 ◽  
Vol 19 (10) ◽  
pp. 761-768 ◽  
Author(s):  
LUIS P. CHIMENTO ◽  
ALEXANDER FEINSTEIN
Keyword(s):  
Gravitational Field ◽  
Scalar Field ◽  
Field Model ◽  
Constant Function ◽  
Field Potentials ◽  
Field Equations ◽  
Large Window ◽  
The Family ◽  
Stable Solutions ◽  
Linear Scalar

We study spatially flat isotropic universes driven by k-essence. It is shown that Friedmann and k-field equations may be analytically integrated for arbitrary k-field potentials during evolution with a constant baryotropic index. It follows that there is an infinite number of dynamically different k-theories with equivalent kinematics of the gravitational field. We show that there is a large "window" of stable solutions, and that the dust-like behavior separates stable from unstable expansion. Restricting to the family of power law solutions, it is argued that the linear scalar field model, with constant function F, is isomorphic to a model with divergent speed of sound and this makes them less suitable for cosmological modeling than the nonlinear k-field solutions we find in this paper.

scholarly journals Quasinormal Modes of Charged Black Holes in Higher-Dimensional Einstein-Power-Maxwell Theory

Axioms ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 33 ◽  
Author(s):  
Grigoris Panotopoulos
Keyword(s):  
Black Holes ◽  
Scalar Field ◽  
Electric Charge ◽  
Quasinormal Modes ◽  
Space Time ◽  
Maxwell Theory ◽  
Charged Black Holes ◽  
Higher Dimensional ◽  
The Impact ◽  
Scalar Perturbations

We compute the quasinormal frequencies for scalar perturbations of charged black holes in five-dimensional Einstein-power-Maxwell theory. The impact on the spectrum of the electric charge of the black holes, of the angular degree, of the overtone number, and of the mass of the test scalar field is investigated in detail. The quasinormal spectra in the eikonal limit are computed as well for several different space-time dimensionalities.

scholarly journals THE GEOMETRIC PICTURE OF GENERALIZED-CP AND HIGGS-FAMILY TRANSFORMATIONS IN THE TWO-HIGGS-DOUBLET MODEL

2011 ◽  
Vol 26 (05) ◽  
pp. 769-808 ◽  
Author(s):  
P. M. FERREIRA ◽  
HOWARD E. HABER ◽  
M. MANIATIS ◽  
O. NACHTMANN ◽  
JOÃO P. SILVA
Keyword(s):  
Scalar Field ◽  
Higgs Doublet ◽  
Geometric Interpretation ◽  
Geometric Description ◽  
Gauge Invariant ◽  
Doublet Model ◽  
Bilinear Functions ◽  
Two Higgs Doublet Model ◽  
Geometric Picture ◽  
Higgs Fields

In the two-Higgs-doublet model (THDM), generalized-CP transformations ([Formula: see text] where X is unitary) and unitary Higgs-family transformations (φi→Uijφj) have recently been examined in a series of papers. In terms of gauge-invariant bilinear functions of the Higgs fields φi, the Higgs-family transformations and the generalized-CP transformations possess a simple geometric description. Namely, these transformations correspond in the space of scalar-field bilinears to proper and improper rotations, respectively. In this formalism, recent results relating generalized CP transformations with Higgs-family transformations have a clear geometric interpretation. We will review what is known regarding THDM symmetries, as well as derive new results concerning those symmetries, namely how they can be interpreted geometrically as applications of several CP transformations.

STABILITY OF SCHWARZSCHILD BLACK HOLE IN THE MASSIVE BRANS-DICKE THEORY

1986 ◽  
Vol 01 (03) ◽  
pp. 709-729 ◽  
Author(s):  
O.J. KWON ◽  
Y.D. KIM ◽  
Y.S. MYUNG ◽  
B.H. CHO ◽  
Y.J. PARK
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Gravitational Wave ◽  
Scalar Wave ◽  
Schwarzschild Black Hole ◽  
The Real ◽  
Gravitational Perturbations ◽  
Scalar Perturbations

For the nontachyonic mass (c<0, µ2<6), we have found that all nonstatic perturbations (odd-, even-parity and scalar perturbations) allow only the real values of frequency k. This means that the black hole in the massive Brans-Dicke theory is classically stable. However, for the tachyonic mass of scalar field (c>0, µ2>6), we find that the massive Brans-Dicke theory is classically unstable. We also emphasize that the potential forms of odd-parity perturbations is simply given by the pure-gravitational perturbations. For the even-parity case, we obtain the same potential just as Zerilli’s case by combining the even-parity gravitational wave and scalar wave. For static perturbations (k=0) and c>0, only the odd- and even-parity cases with L=0, 1 is allowed to avoid exponentially growing modes.

scholarly journals A CHIRAL SCHWINGER MODEL, ITS CONSTRAINT STRUCTURE AND APPLICATIONS TO ITS QUANTIZATION

2008 ◽  
Vol 23 (06) ◽  
pp. 855-869 ◽  
Author(s):  
PAUL BRACKEN
Keyword(s):  
Scalar Field ◽  
Canonical Quantization ◽  
Gauge Invariant ◽  
Invariant Model ◽  
Schwinger Model ◽  
Gauge Fixing ◽  
Dirac Brackets ◽  
Constraint Structure

The Jackiw–Rajaraman version of the chiral Schwinger model is studied as a function of the renormalization parameter. The constraints are obtained and they are used to carry out canonical quantization of the model by means of Dirac brackets. By introducing an additional scalar field, it is shown that the model can be made gauge invariant. The gauge invariant model is quantized by establishing a pair of gauge fixing constraints in order that the method of Dirac can be used.

Sign in / Sign up

Export Citation Format

Share Document