scholarly journals Gravitational production of vector dark matter

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Aqeel Ahmed ◽  
Bohdan Grzadkowski ◽  
Anna Socha
Keyword(s):  
Dark Matter ◽  
Equation Of State ◽  
Canonical Quantization ◽  
State Parameter ◽  
Approximate Solutions ◽  
De Sitter ◽  
The Standard Model ◽  
Relic Abundance ◽  
Generic Equation ◽  
Viable Mechanism

Abstract A model of vector dark matter that communicates with the Standard Model only through gravitational interactions has been investigated. It has been shown in detail how does the canonical quantization of the vector field in varying FLRW geometry implies a tachyonic enhancement of some of its momentum modes. Approximate solutions of the mode equation have been found and verified against exact numerical ones. De Sitter geometry has been assumed during inflation while after inflation a non-standard cosmological era of reheating with a generic equation of state has been adopted which is followed by the radiation-dominated universe. It has been shown that the spectrum of dark vectors produced gravitationally is centered around a characteristic comoving momentum k⋆ that is determined in terms of the mass of the vector mX, the Hubble parameter during in- flation HI, the equation of state parameter w and the efficiency of reheating γ. Regions in the parameter space consistent with the observed dark matter relic abundance have been determined, justifying the gravitational production as a viable mechanism for vector dark matter. The results obtained in this paper are applicable within various possible models of inflation/reheating with non-standard cosmology parametrized effectively by the corresponding equation of state and efficiency of reheating.

scholarly journals Resurrecting low-mass axion dark matter via a dynamical QCD scale

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Lucien Heurtier ◽  
Fei Huang ◽  
Tim M.P. Tait
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Temperature Dependent ◽  
Axion Field ◽  
Wide Range ◽  
The Standard Model ◽  
Low Mass ◽  
Higher Temperature ◽  
Relic Abundance ◽  
Dependent Mass

Abstract In the framework where the strong coupling is dynamical, the QCD sector may confine at a much higher temperature than it would in the Standard Model, and the temperature-dependent mass of the QCD axion evolves in a non-trivial way. We find that, depending on the evolution of ΛQCD, the axion field may undergo multiple distinct phases of damping and oscillation leading generically to a suppression of its relic abundance. Such a suppression could therefore open up a wide range of parameter space, resurrecting in particular axion dark-matter models with a large Peccei-Quinn scale fa ≫ 1012 GeV, i.e., with a lighter mass than the standard QCD axion.

scholarly journals BRANE–BULK ENERGY EXCHANGE AND AGEGRAPHIC DARK ENERGY

2010 ◽  
Vol 19 (03) ◽  
pp. 305-316 ◽  
Author(s):  
AHMAD SHEYKHI
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Normal State ◽  
Energy Exchange ◽  
State Parameter ◽  
Effective Equation ◽  
Agegraphic Dark Energy ◽  
Equation Of State Parameter ◽  
Bulk Energy

We consider the agegraphic models of dark energy in a braneworld scenario with brane–bulk energy exchange. We assume that the adiabatic equation for the dark matter is satisfied while it is violated for the agegraphic dark energy due to the energy exchange between the brane and the bulk. Our study shows that with the brane–bulk interaction, the equation of state parameter of agegraphic dark energy on the brane, wD, can have a transition from the normal state, where wD > -1, to the phantom regime, where wD < -1, while the effective equation of state for dark energy always satisfies [Formula: see text].

A study on the modified holographic Ricci dark energy in logarithmic f(T) gravity

2013 ◽  
Vol 91 (4) ◽  
pp. 351-354 ◽  
Author(s):  
Antonio Pasqua ◽  
Surajit Chattopadhyay
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Modified Gravity ◽  
State Parameter ◽  
Ricci Dark Energy ◽  
Equation Of State Parameter ◽  
Interaction Term ◽  
The Universe

In this paper, we have studied and investigated the behavior of a modified holographic Ricci dark energy (DE) model interacting with pressureless dark matter (DM) under the theory of modified gravity, dubbed logarithmic f(T) gravity. We have chosen the interaction term between DE and DM in the form Q = 3γHρm and investigated the behavior of the torsion, T, the Hubble parameter, H, the equation of state parameter, ωDE, the energy density of DE, ρDE, and the energy density contribution due to torsion, ρT, as functions of the redshift, z. We have found that T increases with the redshift, z, H increases with the evolution of the universe, ωDE has a quintessence-like behavior, and both energy densities increase going from higher to lower redshifts.

scholarly journals Flipped U(1) extended standard model and Majorana dark matter

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Cao H. Nam
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Boson Mass ◽  
Type I ◽  
Seesaw Mechanism ◽  
Gauge Symmetries ◽  
The Standard Model ◽  
Gauge Boson Mass ◽  
The Right ◽  
Relic Abundance

AbstractWe propose a general flavor-independent extension of the Standard Model (SM) with the minimal particle content, based on the symmetry $$SU(3)_C\times SU(2)_L\times U(1)_{Y'}\times U(1)_X\times Z_2$$ S U ( 3 ) C × S U ( 2 ) L × U ( 1 ) Y ′ × U ( 1 ) X × Z 2 . In this scenario, the charge operator is identified in terms of the charges of two U(1) gauge symmetries. The light neutrino masses are generated via Type-I seesaw mechanism only with two heavy right-handed neutrinos acquiring their Majorana masses through the $$U(1)_{Y'}\times U(1)_X$$ U ( 1 ) Y ′ × U ( 1 ) X symmetry breaking. We study various experimental constraints on the parameters of the model and investigate the phenomenology of the right-handed neutrino dark matter (DM) candidate assigned a $$Z_2$$ Z 2 -odd parity. We find that the most important constraints are the observed DM relic abundance, the current LHC limits, and the ambiguity of the SM neutral gauge boson mass.

DIRECT VERSUS INDIRECT SEARCHES FOR NEUTRALINO DARK MATTER

1992 ◽  
Vol 07 (09) ◽  
pp. 733-747 ◽  
Author(s):  
A. BOTTINO ◽  
V. DE ALFARO ◽  
N. FORNENGO ◽  
A. MORALES ◽  
J. PUIMEDÓN ◽  
...  
Keyword(s):  
Experimental Data ◽  
Dark Matter ◽  
Standard Model ◽  
Coupling Strength ◽  
Supersymmetric Extension ◽  
Set Constraints ◽  
The Standard Model ◽  
Search Data ◽  
Relic Abundance ◽  
Minimal Supersymmetric Extension

Direct search for neutralino dark matter is analyzed in the framework of the minimal supersymmetric extension of the standard model, using a realistic evaluation of the neutralino relic abundance which also includes radiative corrections to the Higgs masses. Relevance of the present (Ge detectors) experimental data to set constraints on the parameters of the model is discussed and expectations for future experiments which involve neutralino-nucleus coherent processes are investigated. These results are compared to those obtained in a previous paper from indirect search data. In the present analysis particular attention is paid to the theoretical uncertainties due to the different estimates of the Higgs-nucleon coupling strength.

scholarly journals Forbidden dark matter annihilations into Standard Model particles

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Raffaele Tito D’Agnolo ◽  
Di Liu ◽  
Joshua T. Ruderman ◽  
Po-Jen Wang
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Relevant Parameter ◽  
Annihilation Rate ◽  
High Luminosity ◽  
Muon Mass ◽  
Electron Positron ◽  
Dark Matter Mass ◽  
The Standard Model ◽  
Relic Abundance

Abstract We present kinematically forbidden dark matter annihilations into Standard Model leptons. This mechanism precisely selects the dark matter mass that gives the observed relic abundance. This is qualitatively different from existing models of thermal dark matter, where fixing the relic density typically leaves open orders of magnitude of viable dark matter masses. Forbidden annihilations require the dark matter to be close in mass to the particles that dominate its annihilation rate. We show examples where the dark matter mass is close to the muon mass, the tau mass, or the average of the tau and muon masses. We find that most of the relevant parameter space can be covered by the next generation of proposed beam-dump experiments and future high-luminosity electron positron colliders. Forbidden dark matter predicts large couplings to the Standard Model that can explain the observed value of (g − 2)μ.

scholarly journals Stealth decaying spin-1 dark matter

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Cédric Delaunay ◽  
Teng Ma ◽  
Yotam Soreq
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Direct Detection ◽  
Gauge Coupling ◽  
Indirect Detection ◽  
Cosmological Time ◽  
Electron Neutrinos ◽  
The Standard Model ◽  
Lepton Decays ◽  
Relic Abundance

Abstract We consider models of decaying spin-1 dark matter whose dominant coupling to the standard model sector is through a dark-Higgs Yukawa portal connecting a TeV-scale vector-like lepton to the standard model (right-handed) electron. Below the electron-positron threshold, dark matter has very slow, loop-suppressed decays to photons and (electron) neutrinos, and is stable on cosmological time-scale for sufficiently small gauge coupling values. Its relic abundance is set by in-equilibrium dark lepton decays, through the freeze-in mechanism. We show that this model accommodates the observed dark matter abundance for natural values of its parameters and a dark matter mass in the ∼ 5 keV to 1 MeV range, while evading constraints from direct detection, indirect detection, stellar cooling and cosmology. We also consider the possibility of a nonzero gauge kinetic mixing with the standard model hypercharge field, which is found to yield a mild impact on the model’s phenomenology.

scholarly journals Fermion singlet dark matter in a pseudoscalar dark matter portal

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Bastián Díaz Sáez ◽  
Patricio Escalona ◽  
Sebastián Norero ◽  
Alfonso Zerwekh
Keyword(s):  
Dark Matter ◽  
Parameter Space ◽  
Indirect Detection ◽  
Dirac Fermion ◽  
Simple Extension ◽  
Higgs Decay ◽  
The Standard Model ◽  
Matter Model ◽  
Relic Abundance ◽  
Dark Matter Model

Abstract We explore a simple extension to the Standard Model containing two gauge singlets: a Dirac fermion and a real pseudoscalar. In some regions of the parameter space both singlets are stable without the necessity of additional symmetries, then becoming a possible two-component dark matter model. We study the relic abundance production via freeze-out, with the latter determined by annihilations, conversions and semi-annihilations. Experimental constraints from invisible Higgs decay, dark matter relic abundance and direct/indirect detection are studied. We found three viable regions of the parameter space, and the model is sensitive to indirect searches.

scholarly journals Exploring direct detection suppressed regions in a simple 2-scalar mediator model of scalar dark matter

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Jérôme Claude ◽  
Stephen Godfrey
Keyword(s):  
Dark Matter ◽  
Simple Model ◽  
Standard Model ◽  
Parameter Space ◽  
Cross Sections ◽  
Direct Detection ◽  
Detection Limits ◽  
Interference Effects ◽  
The Standard Model ◽  
Relic Abundance

AbstractWe explore regions of parameter space that give rise to suppressed direct detection cross sections in a simple model of scalar dark matter with a scalar portal that mixes with the standard model Higgs. We found that even this simple model allows considerable room in the parameter space that has not been excluded by direct detection limits. A number of effects leading to this result have been previously noted. Our main new result explores interference effects between different contributions to DM annihilation when the DM mass is larger than the scalar portal mass. New annihilation channels open up and the parameters of the model need to compensate to give the correct DM relic abundance, resulting in smaller direct detection cross sections. We find that even in a very simple model of DM there are still sizeable regions of parameter space that are not ruled out by experiment.

scholarly journals Searching for lepton portal dark matter with colliders and gravitational waves

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Jia Liu ◽  
Xiao-Ping Wang ◽  
Ke-Pan Xie
Keyword(s):  
Dark Matter ◽  
Higgs Boson ◽  
Scalar Potential ◽  
Majorana Fermion ◽  
Charged Scalar ◽  
First Order Phase Transition ◽  
Lepton Colliders ◽  
The Standard Model ◽  
Relic Abundance ◽  
First Order Phase

Abstract We study the lepton portal dark matter (DM) model in which the relic abundance is determined by the portal coupling among the Majorana fermion DM candidate χ, the singlet charged scalar mediator S± and the Standard Model (SM) right-handed lepton. The direct and indirect searches are not sensitive to this model. This article studies the lepton portal coupling as well as the scalar portal coupling (between S± and SM Higgs boson), as the latter is generally allowed in the Lagrangian. The inclusion of scalar portal coupling not only significantly enhances the LHC reach via the gg → h* → S+S− process, but also provides a few novel signal channels, such as the exotic decays and coupling devi- ations of the Higgs boson, offering new opportunities to probe the model. In addition, we also study the Drell-Yan production of S+S− at future lepton colliders, and find out that the scenario where one S± is off-shell can be used to measure the lepton portal coupling directly. In particular, we are interested in the possibility that the scalar potential triggers a first-order phase transition and hence provides the stochastic gravitational wave (GW) signals. In this case, the terrestrial collider experiments and space-based GW detectors serve as complementary approaches to probe the model.

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