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 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.

IS GRAVITINO CONDENSATION POSSIBLE?

2004 ◽  
Vol 13 (05) ◽  
pp. 923-933 ◽  
Author(s):  
M. D. POLLOCK
Keyword(s):  
Vacuum Energy ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Internal Space ◽  
Superstring Theory ◽  
Spontaneous Compactification ◽  
Expectation Value ◽  
Hidden Sector ◽  
Kähler Potential ◽  
Dimensionless Combination

The condensation of fermion bilinears in the dimensionally-reduced, E 8× E '8 heterotic superstring theory often refers to the E'8 hidden-sector gauginos, but in principle condensation may also occur in the compactified internal space, for example of the gravitino and the spin-1/2 Majorana–Weyl field λ of eleven-dimensional supergravity. This possibility, raised by Duff and Orzalesi as a method of spontaneous compactification that maintains vanishing vacuum energy (cosmological constant), was subsequently considered in the context of the heterotic superstring theory by Helayël–Neto and Smith and by the present author, assuming the internal-space gravitinos [Formula: see text] to condense close to the compactification scale M c ~M P /10. Here, by including the four-fermion terms in the Lagrangian density ℒ, we point out that the observable-sector gravitinos ψi and gauginos g typically have comparable, but not identical, masses m3/2~mg~M c as a result of this process. Hence, such condensation is only permitted either at the much lower scale [Formula: see text] (as for the hidden-sector gaugino condensation), so that [Formula: see text], the upper limit on mg ensuring that the Higgs doublets are sufficiently light or, more plausibly, by setting 1 TeV ~mg≪m3/2~M c , which requires a constraint on the condensate parameters. If the three-index field [Formula: see text] also condenses, then the vacuum expectation value of the dimensionless combination [Formula: see text] of the dilaton A r and modulus B r is fixed at a scale ~1, thus yielding the Kähler potential K and hence m3/2~M c Since B r is determined from supersymmetry, this mechanism determines A r .

17 keV NEUTRINO AND MAJORON MODELS

1992 ◽  
Vol 07 (09) ◽  
pp. 2021-2031 ◽  
Author(s):  
ANJAN S. JOSHIPURA
Keyword(s):  
Dark Matter ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Expectation Value ◽  
Dirac Neutrino ◽  
Dirac Mass ◽  
Left Handed ◽  
The Invisible

A model for the 17 keV Dirac neutrino is considered in the framework of the SU(2) × U(1) theory. No right-handed neutrinos are introduced. The Dirac mass for the neutrino arises from the Le+Lτ–Lμ invariant couplings of the left-handed neutrinos to an SU(2) triplet. An SU(2) singlet field is introduced to suppress the Majoron coupling to the Z. This makes the model consistent with the LEP results on the invisible Z width. The singlet vacuum expectation value ω is constrained to be ≤O(80 MeV) from cosmological considerations. For, ω≈80 MeV, the 17 keV neutrino is shown to provide the bulk of the dark matter.

scholarly journals Modulus τ linking leptonic CP violation to baryon asymmetry in A4 modular invariant flavor model

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Hiroshi Okada ◽  
Yusuke Shimizu ◽  
Morimitsu Tanimoto ◽  
Takahiro Yoshida
Keyword(s):  
Cp Violation ◽  
Effective Mass ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Baryon Asymmetry ◽  
Neutrino Masses ◽  
Normal Hierarchy ◽  
Modular Invariant ◽  
Mixing Angles ◽  
Expectation Value

Abstract We propose an A4 modular invariant flavor model of leptons, in which both CP and modular symmetries are broken spontaneously by the vacuum expectation value of the modulus τ. The value of the modulus τ is restricted by the observed lepton mixing angles and lepton masses for the normal hierarchy of neutrino masses. The predictive Dirac CP phase δCP is in the ranges [0°, 50°], [170°, 175°] and [280°, 360°] for Re [τ] < 0, and [0°, 80°], [185°, 190°] and [310°, 360°] for Re [τ] > 0. The sum of three neutrino masses is predicted in [60, 84] meV, and the effective mass for the 0νββ decay is in [0.003, 3] meV. The modulus τ links the Dirac CP phase to the cosmological baryon asymmetry (BAU) via the leptogenesis. Due to the strong wash-out effect, the predictive baryon asymmetry YB can be at most the same order of the observed value. Then, the lightest right-handed neutrino mass is restricted in the range of M1 = [1.5, 6.5] × 1013 GeV. We find the correlation between the predictive YB and the Dirac CP phase δCP. Only two predictive δCP ranges, [5°, 40°] (Re [τ] > 0) and [320°, 355°] (Re [τ] < 0) are consistent with the BAU.

scholarly journals UTILITY OF A SPECIAL SECOND SCALAR DOUBLET

2008 ◽  
Vol 23 (09) ◽  
pp. 647-652 ◽  
Author(s):  
ERNEST MA
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Neutrino Mass ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Grand Unification ◽  
Particle Interactions ◽  
Expectation Value ◽  
The Standard Model

This review deals with the recent resurgence of interest in adding a second scalar doublet (η+, η0) to the Standard Model of particle interactions. In most studies, it is taken for granted that η0 should have a nonzero vacuum expectation value, even if it may be very small. What if there is an exactly conserved symmetry which ensures 〈η0 〉 = 0? The phenomenological ramifications of this idea include dark matter, radiative neutrino mass, leptogenesis, and grand unification.

scholarly journals Left–right model from gauge-Higgs unification with dark matter

2015 ◽  
Vol 30 (12) ◽  
pp. 1550063 ◽  
Author(s):  
Francisco J. de Anda
Keyword(s):  
Dark Matter ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Dark Matter Candidate ◽  
Symmetric Model ◽  
Dimensional Model ◽  
Expectation Value ◽  
Fermion Masses ◽  
The Standard Model ◽  
Five Dimensional Model

We propose a five-dimensional model based on the idea of Gauge-Higgs Unification (GHU) with the gauge group SO(5) × U(1) in Randall–Sundrum (RS) spacetime. We obtain a left–right (LR) symmetric model with a stable scalar identified as a dark matter candidate. This stable scalar obtains a vacuum expectation value (VEV) that gives mass to fermions in the bulk through the Hosotani Mechanism. There is a scalar localized on a brane and gives contributions to fermion masses. This scalar fits the observed Higgs boson data. We are able to fit all the Standard Model (SM) observables while evading constraints.

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.

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.

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.

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