scholarly journals Vector dark matter from a gauged SU(2) symmetry

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Takaaki Nomura ◽  
Hiroshi Okada ◽  
Seokhoon Yun
Keyword(s):  
Dark Matter ◽  
Group Representation ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Scalar Fields ◽  
Mass Relation ◽  
Dark Sector ◽  
Dark Matter Annihilation ◽  
Gauge Bosons ◽  
General Mass

Abstract We propose a scenario of dark sector described by a hidden SU(2) gauge symmetry which is broken by a vacuum expectation value(VEV) of a scalar multiplet. We discuss a general mass relation among SU(2) gauge bosons after spontaneous symmetry breaking which is determined by weight of gauge group representation associated with a scalar multiplet developing VEV. Then a model with quintet and triplet scalar fields is discussed in which hidden gauge boson can be dark matter(DM) stabilized by remnant discrete Z2 symmetry and resonant dark matter annihilation is realized by mass relation between DM and mediator. We estimate relic density and spin independent DM-nucleon scattering cross section searching for allowed parameter region.

scholarly journals Minimal scoto-seesaw mechanism with spontaneous CP violation

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
D. M. Barreiros ◽  
F. R. Joaquim ◽  
R. Srivastava ◽  
J. W. F. Valle
Keyword(s):  
Dark Matter ◽  
Cp Violation ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Discrete Symmetry ◽  
Double Beta Decay ◽  
Neutrino Masses ◽  
Seesaw Mechanism ◽  
Cosmological Observations ◽  
Scalar Singlet

Abstract We propose simple scoto-seesaw models to account for dark matter and neutrino masses with spontaneous CP violation. This is achieved with a single horizontal $$ {\mathcal{Z}}_8 $$ Z 8 discrete symmetry, broken to a residual $$ {\mathcal{Z}}_2 $$ Z 2 subgroup responsible for stabilizing dark matter. CP is broken spontaneously via the complex vacuum expectation value of a scalar singlet, inducing leptonic CP-violating effects. We find that the imposed $$ {\mathcal{Z}}_8 $$ Z 8 symmetry pushes the values of the Dirac CP phase and the lightest neutrino mass to ranges already probed by ongoing experiments, so that normal-ordered neutrino masses can be cornered by cosmological observations and neutrinoless double beta decay experiments.

scholarly journals Scale-invariance, dynamically induced Planck scale and inflation in the Palatini formulation

2021 ◽  
Vol 2105 (1) ◽  
pp. 012005
Author(s):  
Ioannis D. Gialamas ◽  
Alexandros Karam ◽  
Thomas D. Pappas ◽  
Antonio Racioppi ◽  
Vassilis C. Spanos
Keyword(s):  
Scale Invariance ◽  
Planck Scale ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Scalar Fields ◽  
Scale Invariant ◽  
Expectation Value ◽  
Hilbert Action

Abstract We present two scale invariant models of inflation in which the addition of quadratic in curvature terms in the usual Einstein-Hilbert action, in the context of Palatini formulation of gravity, manages to reduce the value of the tensor-to-scalar ratio. In both models the Planck scale is dynamically generated via the vacuum expectation value of the scalar fields.

scholarly journals LHC Probes of TeV-Scale Scalars in SO(10) Grand Unification

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Ufuk Aydemir ◽  
Tanumoy Mandal
Keyword(s):  
Scalar Field ◽  
Gauge Symmetry ◽  
Symmetry Breaking ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Gluon Fusion ◽  
Grand Unification ◽  
Gauge Bosons ◽  
The Standard Model ◽  
Last Stage

We investigate the possibility of TeV-scale scalars as low energy remnants arising in the nonsupersymmetric SO(10) grand unification framework where the field content is minimal. We consider a scenario where the SO(10) gauge symmetry is broken into the gauge symmetry of the Standard Model (SM) through multiple stages of symmetry breaking, and a colored and hypercharged scalar χ picks a TeV-scale mass in the process. The last stage of the symmetry breaking occurs at the TeV-scale where the left-right symmetry, that is, SU(2)L⊗SU(2)R⊗U(1)B-L⊗SU(3)C, is broken into that of the SM by a singlet scalar field S of mass MS~1 TeV, which is a component of an SU(2)R-triplet scalar field, acquiring a TeV-scale vacuum expectation value. For the LHC phenomenology, we consider a scenario where S is produced via gluon-gluon fusion through loop interactions with χ and also decays to a pair of SM gauge bosons through χ in the loop. We find that the parameter space is heavily constrained from the latest LHC data. We use a multivariate analysis to estimate the LHC discovery reach of S into the diphoton channel.

scholarly journals Quantum fluctuation of stress tensor in a higher-derivative scalar field theory around a cosmic string

2021 ◽  
pp. 2150150
Author(s):  
Nahomi Kan ◽  
Masashi Kuniyasu ◽  
Kiyoshi Shiraishi
Keyword(s):  
Scalar Field ◽  
Stress Tensor ◽  
Cosmic String ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Scalar Fields ◽  
Vacuum Fluctuation ◽  
Higher Derivative ◽  
Scalar Theories ◽  
Quantum Stress Tensor

In this paper, we calculate the vacuum fluctuation of the stress tensor of a higher-derivative theory around a thin cosmic string. To this end, we adopt the method to obtain the stress tensor from the effective action developed by Gibbons et al. By their method, the quantum stress tensor of higher-derivative scalar theories without self-interaction is expressed as a simple sum of quantum stress tensors of free massive scalar fields. Unlike the vacuum expectation value of the scalar field squared obtained in the similar model, there appears no reduction of the values near the conical singularity.

scholarly journals RELAXATION MECHANISMS: FROM STRING MODULI TO AXIONS

1995 ◽  
Vol 10 (39) ◽  
pp. 2993-2999 ◽  
Author(s):  
C.E. VAYONAKIS
Keyword(s):  
String Theory ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Scalar Fields ◽  
Relaxation Mechanism ◽  
Expectation Value

The relaxation mechanism of Damour-Polyakov for fixing the vacuum expectation value of certain scalar fields (moduli) in string theory could provide a convenient framework for the Peccei- Quinn relaxation mechanism and remove the narrow “axion window”.

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 Dark matter annihilation into leptons through gravity portals

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Xudong Sun ◽  
Ben-Zhong Dai
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Order Term ◽  
Gravitational Interaction ◽  
Dark Matter Particle ◽  
Higgs Field ◽  
Scalar Fields ◽  
Effective Field ◽  
Leading Order ◽  
Dark Matter Annihilation

Abstract Dark matter (DM) constitutes 85% of the matter in the Universe. However, its specific particle property is still unclear. The fundamentals of DM particles subject to gravitational interaction, and that the lepton excess in cosmic rays may originate from DM particles, inspired us to investigate DM particle properties beyond the standard model. We assume that a leptophilic SU(2) doublet exists in nature as the mediator connecting DM with visible leptons. Since general relativity is not renormalizable at the quantum level, it should be regarded as an effective field theory’s leading order term. One species of the next-to-leading-order term should be operators linear to the Ricci scalar and containing scalar fields, such as the Higgs field, scalar DM, or the newly introduced SU(2) scalar doublet. These operators can cause DM annihilation through gravity portals. We analyzed constraints from the cosmic antiproton flux, DM relic abundance, cosmic positron flux, cosmic microwave background, and direct detection experiments. The result shows that there is a vast parameter space that is compatible with current experiments. DM with a mass of electroweak scale is only allowed to annihilate into leptons. We further show that the purely gravitational DM better explains the DArk Matter Particle Explorer cosmic lepton excess. Our work provides a promising mechanism for DM particles to connect with standard model particles.

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 The Higgs field and the Jordan Brans Dicke cosmology

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
Onder Dunya ◽  
Levent Akant ◽  
Metin Arik ◽  
Yelda Kardas ◽  
Selale Sahin ◽  
...  
Keyword(s):  
Massive Particle ◽  
Higgs Field ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Scalar Fields ◽  
Scale Factor ◽  
Point Of View ◽  
Nonlinear Sigma Model ◽  
Potential Term ◽  
The Universe

AbstractWe investigate a field theoretical approach to the Jordan–Brans–Dicke (JBD) theory extended with a particular potential term on a cosmological background by starting with the motivation that the Higgs field and the scale factor of the universe are related. Based on this relation, it is possible to come up with mathematically equivalent but two different interpretations. From one point of view while the universe is static, the masses of the elementary particles change with time. The other one, which we stick with throughout the manuscript, is that while the universe is expanding, particle masses are constant. Thus, a coupled Lagrangian density of the JBD field and the scale factor (the Higgs field), which exhibit a massive particle and a linearly expanding space in zeroth order respectively, is obtained. By performing a coordinate transformation in the field space for the reduced JBD action whose kinetic part is nonlinear sigma model, the Lagrangian of two scalar fields can be written as uncoupled for the Higgs mechanism. After this transformation, as a result of spontaneous symmetry breaking, the time dependent vacuum expectation value (vev) of the Higgs field and the Higgs bosons which are the particles corresponding to quantized oscillation modes about the vacuum, are found.

scholarly journals Scotogenic neutrino mass with large $$SU(2)_L$$ multiplet fields

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Nilanjana Kumar ◽  
Takaaki Nomura ◽  
Hiroshi Okada
Keyword(s):  
Neutrino Mass ◽  
Mass Matrix ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Scalar Fields ◽  
Lepton Flavor Violation ◽  
Collider Physics ◽  
Mass Model ◽  
Lepton Flavor ◽  
Flavor Violation

Abstract We construct a scotogenic neutrino mass model introducing large $$SU(2)_L$$SU(2)L multiplet fields without adding an extra symmetry. We have introduced extra scalar fields such as a septet, quintet and quartet where we make the vacuum expectation value of quartet scalar to be zero while septet and quintet develop non-zero ones. Then the neutrino mass is generated at one-loop level by introducing quintet fermion. We analyze the neutrino mass matrix taking constraints from lepton flavor violation into account and discuss collider physics regarding charged fermions from large multiplet fields. We have analysed the production and the decays of the quintet fermions, as well as the discovery reach at 14 TeV and 27 TeV LHC.

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