scholarly journals USES OF A SMALL FIELD VALUE WHICH FALLS FROM A METASTABLE MAXIMUM OVER COSMOLOGICAL TIMES

2008 ◽  
Vol 23 (34) ◽  
pp. 2897-2905
Author(s):  
SAUL BARSHAY ◽  
GEORG KREYERHOFF
Keyword(s):  
Small Variation ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Equation Of Motion ◽  
Vacuum Energy Density ◽  
Electron Mass ◽  
Cosmological Time ◽  
Cosmological Context ◽  
Residual Vacuum ◽  
Age Of The Universe

We consider a small, metastable maximum vacuum expectation value b0 of order of a few eV, for a pseudoscalar Goldstone-like field, which is related to the scalar inflaton field ϕ in an idealized model of a cosmological, spontaneously-broken chiral symmetry. The b field allows for relating semi-quantitatively three distinct quantities in a cosmological context. (a) A very small, residual vacuum energy density or effective cosmological constant of [Formula: see text], for λ ~ 3×10-14, the same as an empirical inflaton self-coupling. (b) A tiny neutrino mass, less than b0. (c) A possible small variation downward of the proton to electron mass ratio over cosmological time. The latter arises from the motion downward of the b field over cosmological time, toward a nonzero value. Such behavior is consistent with an equation of motion. We argue that hypothetical b quanta, potentially inducing new long-range forces, are absent, because of negative, effective squared mass in an equation of motion for b-field fluctuations. The assumed flatness of a potential maximum involves a small inverse-time parameter μ ≪ 1/t0, where t0 is the present age of the universe.

DARK-MATTER PARTICLES AND BARYONS FROM INFLATION AND SPONTANEOUS CP VIOLATION IN THE EARLY UNIVERSE

2006 ◽  
Vol 21 (15) ◽  
pp. 1183-1188 ◽  
Author(s):  
SAUL BARSHAY ◽  
GEORG KREYERHOFF
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Cold Dark Matter ◽  
Vacuum Energy ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Baryon Asymmetry ◽  
Vacuum Energy Density ◽  
Expectation Value ◽  
Residual Vacuum

We present aspects of a model which attempts to unify the creation of cold dark matter, a CP-violating baryon asymmetry, and also a small, residual vacuum energy density, in the early universe. The model contains a primary scalar (inflaton) field and a primary pseudoscalar field, which are initially related by a cosmological, chiral symmetry. The nonzero vacuum expectation value of the pseudoscalar field spontaneously breaks CP invariance.

scholarly journals AdS backgrounds and induced gravity

2019 ◽  
Vol 34 (38) ◽  
pp. 2050057
Author(s):  
Hai Lin ◽  
Gaurav Narain
Keyword(s):  
Scalar Field ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Equation Of Motion ◽  
Induced Gravity ◽  
Expectation Value ◽  
Higher Derivative ◽  
Gravity Theories ◽  
Fluctuation Fields ◽  
Ads Geometry

In this paper, we look for AdS solutions to generalized gravity theories in the bulk in various spacetime dimensions. The bulk gravity action includes the action of a non-minimally coupled scalar field with gravity, and a higher-derivative action of gravity. The usual Einstein–Hilbert gravity is induced when the scalar acquires a nonzero vacuum expectation value. The equation of motion in the bulk shows scenarios where AdS geometry emerges on-shell. We further obtain the action of the fluctuation fields on the background at quadratic and cubic orders.

scholarly journals Cosmological evolution of the proton-to-electron mass ratio in an extended Brans–Dicke theory

2019 ◽  
Vol 34 (34) ◽  
pp. 1950277
Author(s):  
Ahmad Mohamadnejad
Keyword(s):  
Particle Physics ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Energy Scale ◽  
Electron Mass ◽  
Mass Ratio ◽  
Higgs Vacuum ◽  
Proton Mass ◽  
Expansion Of The Universe ◽  
The Universe

We study variation of the proton-to-electron mass ratio [Formula: see text] by incorporating Standard Model (SM) of particle physics into an extended Brans–Dicke theory. We show that the evolution of the Higgs vacuum expectation value (VEV), with expansion of the Universe, leads to the variation of the proton-to-electron mass ratio. This is because the electron mass is proportional to the Higgs VEV, while the proton mass is mainly dependent on the quantum chromodynamics (QCD) energy scale, i.e. [Formula: see text]. Therefore, using the experimental and cosmological constraints on the variation of the [Formula: see text], we can constrain the variation of the Higgs VEV. This study is important in understanding the recent claims of the detection of a variation of the proton-to-electron mass ratio in quasar absorption spectra.

scholarly journals THE MASTER FIELD OF QCD2 AND THE 't HOOFT EQUATION

1993 ◽  
Vol 08 (25) ◽  
pp. 2427-2434 ◽  
Author(s):  
MARCO CAVICCHI ◽  
PAOLO DI VECCHIA ◽  
IGOR PESANDO
Keyword(s):  
Saddle Point ◽  
Light Cone ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Equation Of Motion ◽  
Light Cone Gauge ◽  
Expectation Value ◽  
Bilocal Field

We rewrite the action for QCD 2 in the light-cone gauge only in terms of a bilocal mesonic field. In this formalism the 1/N expansion can be done in a straightforward way by a saddle point technique that determines the master field to be identified with the vacuum expectation value of the bilocal field. Finally we show that the equation of motion for the fluctuations around the master field is identical with the 't Hooft meson equation.

scholarly journals COSMOLOGICAL CONCORDANCE MODEL WITH PARTICLE CREATION

2012 ◽  
Vol 18 ◽  
pp. 38-47
Author(s):  
SAULO CARNEIRO
Keyword(s):  
Vacuum Energy ◽  
Particle Creation ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
High Energy ◽  
Vacuum Energy Density ◽  
Late Time ◽  
Energy Limit ◽  
Scale Invariant ◽  
Expectation Value

The creation of ultra-light dark particles in the late-time FLRW spacetime provides a cosmological model in accordance with precise observational tests. The matter creation backreaction implies in this context a vacuum energy density scaling linearly with the Hubble parameter H, which is consistent with the vacuum expectation value of the QCD condensate in a low-energy expanding spacetime. Both the cosmological constant and coincidence problems are alleviated in this scenario. We also explore the opposite, high energy limit of the particle creation process. We show that it leads to a non-singular primordial universe where an early inflationary era takes place, with natural reheating and exit. The generated primordial spectrum is scale invariant and, by supposing that inflation lasts for 60 e-folds, we obtain a scalar expectral index n ≈ 0.97.

scholarly journals Fermionic vacuum polarization around a cosmic string in compactified AdS spacetime

2022 ◽  
Vol 2022 (01) ◽  
pp. 010
Author(s):  
S. Bellucci ◽  
W. Oliveira dos Santos ◽  
E.R. Bezerra de Mello ◽  
A.A. Saharian
Keyword(s):  
Energy Density ◽  
Cosmic String ◽  
Vacuum Energy ◽  
Energy Momentum Tensor ◽  
Minkowski Spacetime ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Momentum Tensor ◽  
Vacuum Energy Density ◽  
Ads Spacetime

Abstract We investigate topological effects of a cosmic string and compactification of a spatial dimension on the vacuum expectation value (VEV) of the energy-momentum tensor for a fermionic field in (4+1)-dimensional locally AdS spacetime. The contribution induced by the compactification is explicitly extracted by using the Abel-Plana summation formula. The mean energy-momentum tensor is diagonal and the vacuum stresses along the direction perpendicular to the AdS boundary and along the cosmic string are equal to the energy density. All the components are even periodic functions of the magnetic fluxes inside the string core and enclosed by compact dimension, with the period equal to the flux quantum. The vacuum energy density can be either positive or negative, depending on the values of the parameters and the distance from the string. The topological contributions in the VEV of the energy-momentum tensor vanish on the AdS boundary. Near the string the effects of compactification and gravitational field are weak and the leading term in the asymptotic expansion coincides with the corresponding VEV in (4+1)-dimensional Minkowski spacetime. At large distances, the decay of the cosmic string induced contribution in the vacuum energy-momentum tensor, as a function of the proper distance from the string, follows a power law. For a cosmic string in the Minkowski bulk and for massive fields the corresponding fall off is exponential. Within the framework of the AdS/CFT correspondence, the geometry for conformal field theory on the AdS boundary corresponds to the standard cosmic string in (3+1)-dimensional Minkowski spacetime compactified along its axis.

scholarly journals Fermionic condensate and the Casimir effect in cosmic string spacetime

2017 ◽  
Vol 26 (07) ◽  
pp. 1750064 ◽  
Author(s):  
A. Kh. Grigoryan ◽  
A. R. Mkrtchyan ◽  
A. A. Saharian
Keyword(s):  
Energy Density ◽  
Cosmic String ◽  
Energy Momentum Tensor ◽  
Casimir Effect ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Momentum Tensor ◽  
Vacuum Energy Density ◽  
Casimir Forces ◽  
Massless Field

We investigate combined effects of nontrivial topology, induced by a cosmic string, and boundaries on the fermionic condensate and the vacuum expectation value (VEV) of the energy–momentum tensor for a massive fermionic field. As geometry of boundaries we consider two plates perpendicular to the string axis on which the field is constrained by the MIT bag boundary condition. By using the Abel–Plana type summation formula, the VEVs in the region between the plates are decomposed into the boundary-free and boundary-induced contributions for general case of the planar angle deficit. The boundary-induced parts in both the fermionic condensate and the energy–momentum tensor vanish on the cosmic string. Fermionic condensate is positive near the string and negative at large distances, whereas the vacuum energy density is negative everywhere. The radial stress is equal to the energy density. For a massless field, the boundary-induced contribution in the VEV of the energy–momentum tensor is different from zero in the region between the plates only and it does not depend on the coordinate along the string axis. In the region between the plates and at large distances from the string, the decay of the topological part is exponential for both massive and massless fields. This behavior is in contrast to that for the VEV of the energy–momentum tensor in the boundary-free geometry with the power law decay for a massless field. The vacuum pressure on the plates is inhomogeneous and vanishes at the location of the string. The corresponding Casimir forces are attractive.

Global symmetries and Noether’s theorem

2018 ◽  
Author(s):  
Michael Kachelriess
Keyword(s):  
Global Symmetries ◽  
Symmetry Transformation ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Quantum Field ◽  
Expectation Value ◽  
Minkowski Space Time ◽  
Integral Measure ◽  
Colour Charge ◽  
Internal Symmetries

Noethers theorem shows that continuous global symmetries lead classically to conservation laws. Such symmetries can be divided into spacetime and internal symmetries. The invariance of Minkowski space-time under global Poincaré transformations leads to the conservation of the four-momentum and the total angular momentum. Examples for conserved charges due to internal symmetries are electric and colour charge. The vacuum expectation value of a Noether current is shown to beconserved in a quantum field theory if the symmetry transformation keeps the path-integral measure invariant.

scholarly journals Field Theoretical Approach for Signal Detection in Nearly Continuous Positive Spectra II: Tensorial Data

Entropy ◽  
2021 ◽  
Vol 23 (7) ◽  
pp. 795
Author(s):  
Vincent Lahoche ◽  
Mohamed Ouerfelli ◽  
Dine Ousmane Samary ◽  
Mohamed Tamaazousti
Keyword(s):  
Principal Component Analysis ◽  
Renormalization Group ◽  
Signal Detection ◽  
Detection Threshold ◽  
Principal Component ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Component Analysis ◽  
Slight Generalization ◽  
Nearly Continuous

The tensorial principal component analysis is a generalization of ordinary principal component analysis focusing on data which are suitably described by tensors rather than matrices. This paper aims at giving the nonperturbative renormalization group formalism, based on a slight generalization of the covariance matrix, to investigate signal detection for the difficult issue of nearly continuous spectra. Renormalization group allows constructing an effective description keeping only relevant features in the low “energy” (i.e., large eigenvalues) limit and thus providing universal descriptions allowing to associate the presence of the signal with objectives and computable quantities. Among them, in this paper, we focus on the vacuum expectation value. We exhibit experimental evidence in favor of a connection between symmetry breaking and the existence of an intrinsic detection threshold, in agreement with our conclusions for matrices, providing a new step in the direction of a universal statement.

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