A real triplet-singlet extended Standard Model: dark matter and collider phenomenology

Abstract We examine the collider and dark matter phenomenology of the Standard Model extended by a hypercharge-zero SU(2) triplet scalar and gauge singlet scalar. In particular, we study the scenario where the singlet and triplet are both charged under a single ℤ2 symmetry. We find that such an extension is capable of generating the observed dark matter density, while also modifying the collider phenomenology such that the lower bound on the mass of the triplet is smaller than in minimal triplet scalar extensions to the Standard Model. A high triplet mass is in tension with the parameter space that leads to novel electroweak phase transitions in the early universe. Therefore, the lower triplet masses that are permitted in this extended model are of particular importance for the prospects of successful electroweak baryogenesis and the generation of gravitational waves from early universe phase transitions.

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Sterile Neutrinos as Dark Matter: Alternative Production Mechanisms in the Early Universe

Universe ◽

10.3390/universe7080264 ◽

2021 ◽

Vol 7 (8) ◽

pp. 264

Author(s):

Daniel Boyanovsky

Keyword(s):

Dark Matter ◽

Distribution Function ◽

Kinetic Equation ◽

Standard Model ◽

Early Universe ◽

Quantum Kinetic Equation ◽

Sterile Neutrinos ◽

The Standard Model ◽

Production Mechanisms ◽

Freeze Out

We study various production mechanisms of sterile neutrinos in the early universe beyond and within the standard model. We obtain the quantum kinetic equations for production and the distribution function of sterile-like neutrinos at freeze-out, from which we obtain free streaming lengths, equations of state and coarse grained phase space densities. In a simple extension beyond the standard model, in which neutrinos are Yukawa coupled to a Higgs-like scalar, we derive and solve the quantum kinetic equation for sterile production and analyze the freeze-out conditions and clustering properties of this dark matter constituent. We argue that in the mass basis, standard model processes that produce active neutrinos also yield sterile-like neutrinos, leading to various possible production channels. Hence, the final distribution function of sterile-like neutrinos is a result of the various kinematically allowed production processes in the early universe. As an explicit example, we consider production of light sterile neutrinos from pion decay after the QCD phase transition, obtaining the quantum kinetic equation and the distribution function at freeze-out. A sterile-like neutrino with a mass in the keV range produced by this process is a suitable warm dark matter candidate with a free-streaming length of the order of few kpc consistent with cores in dwarf galaxies.

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Predictions for axion couplings from ALP cogenesis

Journal of High Energy Physics ◽

10.1007/jhep01(2021)172 ◽

2021 ◽

Vol 2021 (1) ◽

Author(s):

Raymond T. Co ◽

Lawrence J. Hall ◽

Keisuke Harigaya

Keyword(s):

Dark Matter ◽

Standard Model ◽

Early Universe ◽

Decay Constant ◽

Stellar Objects ◽

The Standard Model ◽

Field Velocity

Abstract Adding an axion-like particle (ALP) to the Standard Model, with a field velocity in the early universe, simultaneously explains the observed baryon and dark matter densities. This requires one or more couplings between the ALP and photons, nucleons, and/or electrons that are predicted as functions of the ALP mass. These predictions arise because the ratio of dark matter to baryon densities is independent of the ALP field velocity, allowing a correlation between the ALP mass, ma, and decay constant, fa. The predicted couplings are orders of magnitude larger than those for the QCD axion and for dark matter from the conventional ALP misalignment mechanism. As a result, this scheme, ALP cogenesis, is within reach of future experimental ALP searches from the lab and stellar objects, and for dark matter.

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Kaluza-Klein FIMP dark matter in warped extra-dimensions

Journal of High Energy Physics ◽

10.1007/jhep09(2020)142 ◽

2020 ◽

Vol 2020 (9) ◽

Author(s):

Nicolás Bernal ◽

Andrea Donini ◽

Miguel G. Folgado ◽

Nuria Rius

Keyword(s):

Dark Matter ◽

Standard Model ◽

Early Universe ◽

Extra Dimensions ◽

The Standard Model ◽

Massive Particles ◽

Warped Extra Dimensions ◽

Relic Abundance ◽

First Time ◽

Kaluza Klein

Abstract We study for the first time the case in which Dark Matter (DM) is made of Feebly Interacting Massive Particles (FIMP) interacting just gravitationally with the standard model particles in an extra-dimensional Randall-Sundrum scenario. We assume that both the dark matter and the standard model are localized in the IR-brane and only interact via gravitational mediators, namely the graviton, the Kaluza-Klein gravitons and the radion. We found that in the early Universe DM could be generated via two main processes: the direct freeze-in and the sequential freeze-in. The regions where the observed DM relic abundance is produced are largely compatible with cosmological and collider bounds.

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FREED LEPTOGENESIS

Modern Physics Letters A ◽

10.1142/s0217732311037340 ◽

2011 ◽

Vol 26 (39) ◽

pp. 2983-2996 ◽

Cited By ~ 3

Author(s):

DMITRY V. ZHURIDOV

Keyword(s):

Dark Matter ◽

Lower Bound ◽

Standard Model ◽

Upper Bound ◽

Light Neutrino ◽

Heavy Neutrino ◽

Neutrino Masses ◽

Cp Asymmetry ◽

The Standard Model

Economical extensions of the Standard Model (SM), in which famous Davidson–Ibarra bound on the CP asymmetry relevant for leptogenesis may be significantly relaxed by the loop effects, comparing to predictions of the SM extended only by heavy right-handed neutrinos with hierarchical masses, are discussed. This leads to decreasing of the lower bound on the heavy neutrino masses and increasing of the upper bound on the light neutrino masses, which is testable. In addition, the considered theory may help to solve the dark matter problem.

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Heavy Chiral Fermions and Dark Matter

Advances in High Energy Physics ◽

10.1155/2013/915897 ◽

2013 ◽

Vol 2013 ◽

pp. 1-15 ◽

Cited By ~ 1

Author(s):

Johan Alwall ◽

Jusak Tandean

Keyword(s):

Dark Matter ◽

Standard Model ◽

Recent Observation ◽

New Physics ◽

Heavy Quarks ◽

Fourth Generation ◽

Beyond The Standard Model ◽

Collider Phenomenology ◽

Potential Implication ◽

The Standard Model

Dark matter presents perhaps one of the most compelling direct indications of new physics beyond the standard model with three generations of fermions. In this paper, we survey several scenarios for dark matter in association with a fourth generation of chiral matter. The surveyed scenarios include stable heavy neutrino dark matter, composite dark matter consisting of stable heavy quarks, heavy quarks as mediators between the dark and visible sectors, and the four-generation standard model with the minimal addition of a stable real scalar field. We discuss the basic properties of the models, direct search constraints on their dark matter, and their collider phenomenology, as well as the possible effects of dark matter on the searches for a Higgs boson in the presence of four generations. We also comment on the potential implication of the recent observation of a Higgs-like new particle at the LHC.

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Phase transitions in the early universe

SciPost Physics Lecture Notes ◽

10.21468/scipostphyslectnotes.24 ◽

2021 ◽

Author(s):

Mark Hindmarsh ◽

Marvin Lüben ◽

Johannes Lumma ◽

Martin Pauly

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Standard Model ◽

Gravitational Wave ◽

Gravitational Waves ◽

Early Universe ◽

Order Approximation ◽

First Order ◽

The Standard Model ◽

First Order Phase

These lecture notes are based on a course given by Mark Hindmarsh at the 24th Saalburg Summer School 2018 and written up by Marvin Lüben, Johannes Lumma and Martin Pauly. The aim is to provide the necessary basics to understand first-order phase transitions in the early universe, to outline how they leave imprints in gravitational waves, and advertise how those gravitational waves could be detected in the future. A first-order phase transition at the electroweak scale is a prediction of many theories beyond the Standard Model, and is also motivated as an ingredient of some theories attempting to provide an explanation for the matter-antimatter asymmetry in our Universe. Starting from bosonic and fermionic statistics, we derive Boltzmann's equation and generalise to a fluid of particles with field dependent mass. We introduce the thermal effective potential for the field in its lowest order approximation, discuss the transition to the Higgs phase in the Standard Model and beyond, and compute the probability for the field to cross a potential barrier. After these preliminaries, we provide a hydrodynamical description of first-order phase transitions as it is appropriate for describing the early Universe. We thereby discuss the key quantities characterising a phase transition, and how they are imprinted in the gravitational wave power spectrum that might be detectable by the space-based gravitational wave detector LISA in the 2030s.

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Search for dark matter in association with an energetic photon in pp collisions at $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector

Journal of High Energy Physics ◽

10.1007/jhep02(2021)226 ◽

2021 ◽

Vol 2021 (2) ◽

Author(s):

G. Aad ◽

◽

B. Abbott ◽

D. C. Abbott ◽

A. Abed Abud ◽

...

Keyword(s):

Dark Matter ◽

Transverse Momentum ◽

Standard Model ◽

Confidence Level ◽

Axial Vector ◽

Beyond The Standard Model ◽

Proton Proton ◽

Missing Transverse Momentum ◽

Upper Limits ◽

The Standard Model

Abstract A search for dark matter is conducted in final states containing a photon and missing transverse momentum in proton-proton collisions at $$ \sqrt{s} $$ s = 13 TeV. The data, collected during 2015–2018 by the ATLAS experiment at the CERN LHC, correspond to an integrated luminosity of 139 fb−1. No deviations from the predictions of the Standard Model are observed and 95% confidence-level upper limits between 2.45 fb and 0.5 fb are set on the visible cross section for contributions from physics beyond the Standard Model, in different ranges of the missing transverse momentum. The results are interpreted as 95% confidence-level limits in models where weakly interacting dark-matter candidates are pair-produced via an s-channel axial-vector or vector mediator. Dark-matter candidates with masses up to 415 (580) GeV are excluded for axial-vector (vector) mediators, while the maximum excluded mass of the mediator is 1460 (1470) GeV. In addition, the results are expressed in terms of 95% confidence-level limits on the parameters of a model with an axion-like particle produced in association with a photon, and are used to constrain the coupling gaZγ of an axion-like particle to the electroweak gauge bosons.

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Theoretical uncertainties for cosmological first-order phase transitions

Journal of High Energy Physics ◽

10.1007/jhep04(2021)055 ◽

2021 ◽

Vol 2021 (4) ◽

Author(s):

Djuna Croon ◽

Oliver Gould ◽

Philipp Schicho ◽

Tuomas V. I. Tenkanen ◽

Graham White

Keyword(s):

Phase Transitions ◽

Standard Model ◽

Scale Dependence ◽

Effective Field ◽

Bubble Nucleation ◽

Perturbative Approach ◽

First Order ◽

The Standard Model ◽

First Order Phase ◽

Renormalisation Scale

Abstract We critically examine the magnitude of theoretical uncertainties in perturbative calculations of fist-order phase transitions, using the Standard Model effective field theory as our guide. In the usual daisy-resummed approach, we find large uncertainties due to renormalisation scale dependence, which amount to two to three orders-of-magnitude uncertainty in the peak gravitational wave amplitude, relevant to experiments such as LISA. Alternatively, utilising dimensional reduction in a more sophisticated perturbative approach drastically reduces this scale dependence, pushing it to higher orders. Further, this approach resolves other thorny problems with daisy resummation: it is gauge invariant which is explicitly demonstrated for the Standard Model, and avoids an uncontrolled derivative expansion in the bubble nucleation rate.

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Relativistic Cosmology with an Introduction to Inflation

Universe ◽

10.3390/universe7080276 ◽

2021 ◽

Vol 7 (8) ◽

pp. 276

Author(s):

Muhammad Zahid Mughal ◽

Iftikhar Ahmad ◽

Juan Luis García Guirao

Keyword(s):

Standard Model ◽

Early Universe ◽

Large Scale ◽

Initial Conditions ◽

Big Bang ◽

Relativistic Cosmology ◽

The Standard Model ◽

Big Bang Model ◽

The Big Bang ◽

The Universe

In this review article, the study of the development of relativistic cosmology and the introduction of inflation in it as an exponentially expanding early phase of the universe is carried out. We study the properties of the standard cosmological model developed in the framework of relativistic cosmology and the geometric structure of spacetime connected coherently with it. The geometric properties of space and spacetime ingrained into the standard model of cosmology are investigated in addition. The big bang model of the beginning of the universe is based on the standard model which succumbed to failure in explaining the flatness and the large-scale homogeneity of the universe as demonstrated by observational evidence. These cosmological problems were resolved by introducing a brief acceleratedly expanding phase in the very early universe known as inflation. The cosmic inflation by setting the initial conditions of the standard big bang model resolves these problems of the theory. We discuss how the inflationary paradigm solves these problems by proposing the fast expansion period in the early universe. Further inflation and dark energy in fR modified gravity are also reviewed.

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Extension of Standard Model in multi-spinor field formalism — Visible and dark sectors

International Journal of Modern Physics A ◽

10.1142/s0217751x16300271 ◽

2016 ◽

Vol 31 (18) ◽

pp. 1630027

Author(s):

Ikuo S. Sogami

Keyword(s):

Dark Matter ◽

Standard Model ◽

Dark Sector ◽

Quadratic Interaction ◽

Inflationary Phase ◽

The Standard Model ◽

Visible Sector ◽

Field Formalism ◽

Main Component ◽

Higgs Fields

With multi-spinor fields which behave as triple-tensor products of the Dirac spinors, the Standard Model is extended so as to embrace three families of ordinary quarks and leptons in the visible sector and an additional family of exotic quarks and leptons in the dark sector of our Universe. Apart from the gauge and Higgs fields of the Standard Model symmetry G, new gauge and Higgs fields of a symmetry isomorphic to G are postulated to exist in the dark sector. It is the bi-quadratic interaction between visible and dark Higgs fields that opens a main portal to the dark sector. Breakdowns of the visible and dark electroweak symmetries result in the Higgs boson with mass 125 GeV and a new boson which can be related to the diphoton excess around 750 GeV. Subsequent to a common inflationary phase and a reheating period, the visible and dark sectors follow weakly-interacting paths of thermal histories. We propose scenarios for dark matter in which no dark nuclear reaction takes place. A candidate for the main component of the dark matter is a stable dark hadron with spin 3/2, and the upper limit of its mass is estimated to be 15.1 GeV/c2.

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