scholarly journals Decaying Dark Atom Constituents and Cosmic Positron Excess

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
K. Belotsky ◽  
M. Khlopov ◽  
C. Kouvaris ◽  
M. Laletin
Keyword(s):  
Dark Matter ◽  
Gamma Ray ◽  
Bound State ◽  
Helium Nucleus ◽  
Small Component ◽  
Dominant Component ◽  
The Universe

We present a scenario where dark matter is in the form of dark atoms that can accommodate the experimentally observed excess of positrons in PAMELA and AMS-02 while being compatible with the constraints imposed on the gamma-ray ux from Fermi/LAT. This scenario assumes that the dominant component of dark matter is in the form of a bound state between a helium nucleus and a-2particle and a small component is in the form of a WIMP-like dark atom compatible with direct searches in underground detectors. One of the constituents of this WIMP-like state is a+2metastable particle with a mass of 1 TeV or slightly below that by decaying toe+e+,μ+μ+andτ+τ+produces the observed positron excess. These decays can naturally take place via GUT interactions. If it exists, such a metastable particle can be found in the next run of LHC. The model predicts also the ratio of leptons over baryons in the universe to be close to-3.

scholarly journals Indirect effects of dark matter

2019 ◽  
Vol 28 (13) ◽  
pp. 1941011 ◽  
Author(s):  
K. M. Belotsky ◽  
E. A. Esipova ◽  
A. Kh. Kamaletdinov ◽  
E. S. Shlepkina ◽  
M. L. Solovyov
Keyword(s):  
Dark Matter ◽  
Indirect Effects ◽  
Large Scale ◽  
Gamma Ray ◽  
Space Distribution ◽  
Stable Form ◽  
Final State ◽  
Electron Positron ◽  
Text Mode ◽  
The Universe

Here, we briefly review possible indirect effects of dark matter (DM) of the universe. It includes effects in cosmic rays (CR): first of all, the positron excess at [Formula: see text]500[Formula: see text]GeV and possible electron–positron excess at 1–1.5[Formula: see text]TeV. We tell that the main and least model-dependent constraint on such possible interpretation of CR effects goes from gamma-ray background. Even ordinary [Formula: see text] mode of DM decay or annihilation produces prompt photons (FSR) so much that it leads to contradiction with data on cosmic gamma-rays. We present our attempts to possibly avoid gamma-ray constraint. They concern with peculiarities of both space distribution of DM and their physics. The latter involves complications of decay/annihilation modes of DM, modifications of Lagrangian of DM-ordinary matter interaction and inclusion of mode with identical fermions in final state. In this way, no possibilities to suppress were found except, possibly, the mode with identical fermions. While the case of spatial distribution variation allows achieving consistency between different data. Also, we consider stable form of DM which can interact with baryons. We show which constraint such DM candidate can get from the damping effect in plasma during large-scale structure (LSS) formation in comparison with other existing constraints.

scholarly journals Status of dark matter in the universe

2017 ◽  
Vol 26 (06) ◽  
pp. 1730012 ◽  
Author(s):  
Katherine Freese
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Gravitational Lensing ◽  
Gamma Ray ◽  
Galactic Center ◽  
Data Sets ◽  
Multiple Sources ◽  
Microwave Background ◽  
First Stars ◽  
The Universe

Over the past few decades, a consensus picture has emerged in which roughly a quarter of the universe consists of dark matter. I begin with a review of the observational evidence for the existence of dark matter: rotation curves of galaxies, gravitational lensing measurements, hot gas in clusters, galaxy formation, primordial nucleosynthesis and Cosmic Microwave Background (CMB) observations. Then, I discuss a number of anomalous signals in a variety of data sets that may point to discovery, though all of them are controversial. The annual modulation in the DAMA detector and/or the gamma-ray excess seen in the Fermi Gamma Ray Space Telescope from the Galactic Center could be due to WIMPs; a 3.5 keV X-ray line from multiple sources could be due to sterile neutrinos; or the 511 keV line in INTEGRAL data could be due to MeV dark matter. All of these would require further confirmation in other experiments or data sets to be proven correct. In addition, a new line of research on dark stars is presented, which suggests that the first stars to exist in the universe were powered by dark matter heating rather than by fusion: the observational possibility of discovering dark matter in this way is discussed.

scholarly journals Balancing Asymmetric Dark Matter with Baryon Asymmetry and Dilution of Frozen Dark Matter by Sphaleron Transition

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 275
Author(s):  
Arnab Chaudhuri ◽  
Maxim Yu. Khlopov
Keyword(s):  
Phase Transition ◽  
Dark Matter ◽  
Bound State ◽  
Baryon Asymmetry ◽  
Matter Density ◽  
Helium Nucleus ◽  
Electroweak Phase Transition ◽  
Definite Relationship ◽  
Dark Matter Density ◽  
Asymmetric Dark Matter

In this paper, we study the effect of electroweak sphaleron transition and electroweak phase transition (EWPT) in balancing the baryon excess and the excess stable quarks of the 4th generation. Sphaleron transitions between baryons, leptons and the 4th family of leptons and quarks establish a definite relationship between the value and sign of the 4th family excess and baryon asymmetry. This relationship provides an excess of stable U¯ antiquarks, forming dark atoms—the bound state of (U¯U¯U¯) the anti-quark cluster and primordial helium nucleus. If EWPT is of the second order and the mass of U quark is about 3.5 TeV, then dark atoms can explain the observed dark matter density. In passing by, we show the small, yet negligible dilution in the pre-existing dark matter density, due to the sphaleron transition.

Space Science

2005 ◽  
Author(s):  
Michael D. Lemonick
Keyword(s):  
Dark Matter ◽  
Solid Rock ◽  
Hot Springs ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Nearby Stars ◽  
Gravitational Influence ◽  
New Space ◽  
The Universe ◽  
Modern Astronomy

Astronomy is the only branch of science where the questions are literally cosmic. Its practitioners are trying to answer the most profound questions imaginable, the same questions that philosophers have been wrestling with for thousands of years. How big is the universe? How old is it? What is it made of? Are we alone, or do other intelligent beings live on planets orbiting distant stars? How did the cosmos begin? And how will it end? As recently as a decade ago, none of these questions had been answered in any definitive way. Now, thanks to powerful new space-based observatories and ingenious new techniques for gazing up from the ground, astronomers have cracked some of them. We now know that the universe is 13.7 billion years old, that more than 100 planets circle Sun-like stars right in our celestial neighbour-hood, and that the cosmos is likely to expand forever, until all the stars have burned out and matter itself breaks down. We know that gamma ray bursts—explosions so massive they defied understanding for decades—are exploding stars more powerful than anyone had imagined. Yet plenty of mysteries remain. Astronomers know that the visible stars and galaxies add up to only a fifth or so of the matter in the universe. The rest is some sort of mysterious dark matter, detectable only through its gravitational influence on the visible stuff. The search for dark matter is still a major focus of modern astronomy. Closer to home, there's a major push to find not just planets, but Earthlike planets orbiting nearby stars. The massive, gaseous, Jupiter-like planets found so far are impressive enough, but as far as we know, you need something smaller and more solid to support life—the ultimate goal of planet-searchers. Indeed, while astronomers had long since given up looking for life in our own solar system, biologists have given them new hope. Life, it turns out, can live in far harsher conditions than anyone thought (hot springs, Antarctic ice, inside solid rock), which means it could exist under the surface of Mars or in oceans under the icy coating of Jupiter's moon Europa.

scholarly journals A decaying neutralino as dark matter and its gamma ray spectrum

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
Amin Aboubrahim ◽  
Tarek Ibrahim ◽  
Michael Klasen ◽  
Pran Nath
Keyword(s):  
Dark Matter ◽  
Radiative Decay ◽  
Gamma Ray ◽  
Indirect Detection ◽  
Supersymmetric Particle ◽  
Unified Framework ◽  
Dark Matter Annihilation ◽  
Hidden Sector ◽  
Visible Sector ◽  
The Universe

AbstractIt is shown that a decaying neutralino in a supergravity unified framework is a viable candidate for dark matter. Such a situation arises in the presence of a hidden sector with ultraweak couplings to the visible sector where the neutralino can decay into the hidden sector’s lightest supersymmetric particle (LSP) with a lifetime larger than the lifetime of the universe. We present a concrete model where the MSSM/SUGRA is extended to include a hidden sector comprised of $$U(1)_{X_1} \times U(1)_{X_2}$$ U ( 1 ) X 1 × U ( 1 ) X 2 gauge sector and the LSP of the hidden sector is a neutralino which is lighter than the LSP neutralino of the visible sector. We compute the loop suppressed radiative decay of the visible sector neutralino into the neutralino of the hidden sector and show that the decay can occur with a lifetime larger than the age of the universe. The decaying neutralino can be probed by indirect detection experiments, specifically by its signature decay into the hidden sector neutralino and an energetic gamma ray photon. Such a gamma ray can be searched for with improved sensitivity at Fermi-LAT and by future experiments such as the Square Kilometer Array (SKA) and the Cherenkov Telescope Array (CTA). We present several benchmarks which have a natural suppression of the hadronic channels from dark matter annihilation and decays and consistent with measurements of the antiproton background.

scholarly journals Signatures of primordial black hole dark matter

2014 ◽  
Vol 29 (37) ◽  
pp. 1440005 ◽  
Author(s):  
K. M. Belotsky ◽  
A. E. Dmitriev ◽  
E. A. Esipova ◽  
V. A. Gani ◽  
A. V. Grobov ◽  
...  
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Symmetry Breaking ◽  
Early Universe ◽  
High Energy Physics ◽  
Gamma Ray ◽  
High Energy ◽  
Primordial Black Hole ◽  
Dominant Form ◽  
The Universe

The nonbaryonic dark matter of the Universe is assumed to consist of new stable forms of matter. Their stability reflects symmetry of micro-world and mechanisms of its symmetry breaking. In the early Universe heavy metastable particles can dominate, leaving primordial black holes (PBHs) after their decay, as well as the structure of particle symmetry breaking gives rise to cosmological phase transitions, from which massive black holes (BHs) and/or their clusters can originate. PBHs can be formed in such transitions within a narrow interval of masses about 1017 g and, avoiding severe observational constraints on PBHs, can be a candidate for the dominant form of dark matter. PBHs in this range of mass can give solution of the problem of reionization in the Universe at the redshift z~5–10. Clusters of massive PBHs can serve as a nonlinear seeds for galaxy formation, while PBHs evaporating in such clusters can provide an interesting interpretation for the observations of point-like gamma-ray sources. Analysis of possible PBH signatures represents a universal probe for super-high energy physics in the early Universe in studies of indirect effects of the dark matter.

scholarly journals Detecting Particle Dark Matter Signatures via Cross-Correlation of Gamma-Ray Anisotropies and Cosmic Shear

2014 ◽  
Vol 10 (S306) ◽  
pp. 110-112
Author(s):  
Stefano Camera
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Cross Correlation ◽  
Gamma Ray ◽  
Galactic Halo ◽  
Distant Galaxy ◽  
Γ Rays ◽  
Γ Ray ◽  
Cosmic Shear ◽  
The Universe

AbstractSimilarly to gravitational lensing effects like cosmic shear, cosmological γ-ray emission too is to some extent a tracer of the distribution of dark matter (DM) in the Universe. Intervening DM structures source gravitational lensing distortions of distant galaxy images, and those same galaxies can emit γ rays, either because they host astrophysical sources, or directly by particle DM annihilations or decays occurring in the galactic halo. If such γ rays exhibit correlation with the cosmic shear signal, this will provide novel information on the composition of the extragalactic γ-ray background.

scholarly journals Spin-one dark matter and gamma ray signals from the galactic center

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
H. Hernández-Arellano ◽  
M. Napsuciale ◽  
S. Rodríguez
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Gamma Ray ◽  
Galactic Center ◽  
Photon Emission ◽  
Scalar Coupling ◽  
Initial State ◽  
Internal Bremsstrahlung ◽  
Resonance Effects ◽  
State Radiation

Abstract In this work we study the possibility that the gamma ray excess (GRE) at the Milky Way galactic center come from the annihilation of dark matter with a (1, 0) ⊕ (0, 1) space-time structure (spin-one dark matter, SODM). We calculate the production of prompt photons from initial state radiation, internal bremsstrahlung, final state radiation including the emission from the decay products of the μ, τ or hadronization of quarks. Next we study the delayed photon emission from the inverse Compton scattering (ICS) of electrons (produced directly or in the prompt decay of μ, τ leptons or in the hadronization of quarks produced in the annihilation of SODM) with the cosmic microwave background or starlight. All these mechanisms yield significant contributions only for Higgs resonant exchange, i.e. for M ≈ MH /2, and the results depend on the Higgs scalar coupling to SODM, gs. The dominant mechanism at the GRE bump is the prompt photon production in the hadronization of b quarks produced in $$ \overline{D}D\to \overline{b}b $$ D ¯ D → b ¯ b , whereas the delayed photon emission from the ICS of electrons coming from the hadronization of b quarks produced in the same reaction dominates at low energies (ω < 0.3 GeV ) and prompt photons from c and τ , as well as from internal bremsstrahlung, yield competitive contributions at the end point of the spectrum (ω ≥ 30 GeV ). Taking into account all these contributions, our results for photons produced in the annihilation of SODM are in good agreement with the GRE data for gs ∈ [0.98, 1.01] × 10−3 and M ∈ [62.470, 62.505] GeV . We study the consistency of the corresponding results for the dark matter relic density, the spin-independent dark matter-nucleon cross-section σp and the cross section for the annihilation of dark matter into $$ \overline{b}b $$ b ¯ b , τ+τ−, μ+μ− and γγ, taking into account the Higgs resonance effects, finding consistent results in all cases.

scholarly journals Effective field theory analysis of dark matter-standard model interactions with spin one mediators

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Fabiola Fortuna ◽  
Pablo Roig ◽  
José Wudka
Keyword(s):  
Field Theory ◽  
Dark Matter ◽  
Standard Model ◽  
Effective Field Theory ◽  
Gamma Ray ◽  
Direct Detection ◽  
Effective Field ◽  
Indirect Detection ◽  
Theory Analysis ◽  
Invisible Decay

Abstract We analyze interactions between dark matter and standard model particles with spin one mediators in an effective field theory framework. In this paper, we are considering dark particles masses in the range from a few MeV to the mass of the Z boson. We use bounds from different experiments: Z invisible decay width, relic density, direct detection experiments, and indirect detection limits from the search of gamma-ray emissions and positron fluxes. We obtain solutions corresponding to operators with antisymmetric tensor mediators that fulfill all those requirements within our approach.

scholarly journals On a Possible Origin of the Gamma-ray Excess around the Galactic Center

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1432
Author(s):  
Dmitry O. Chernyshov ◽  
Andrei E. Egorov ◽  
Vladimir A. Dogiel ◽  
Alexei V. Ivlev
Keyword(s):  
Dark Matter ◽  
Gamma Rays ◽  
Molecular Clouds ◽  
Alternative Explanation ◽  
Gamma Ray ◽  
Galactic Center ◽  
The Self ◽  
Large Area ◽  
Mhd Turbulence ◽  
The Standard Model

Recent observations of gamma rays with the Fermi Large Area Telescope (LAT) in the direction of the inner galaxy revealed a mysterious excess of GeV. Its intensity is significantly above predictions of the standard model of cosmic rays (CRs) generation and propagation with a peak in the spectrum around a few GeV. Popular interpretations of this excess are that it is due to either spherically distributed annihilating dark matter (DM) or an abnormal population of millisecond pulsars. We suggest an alternative explanation of the excess through the CR interactions with molecular clouds in the Galactic Center (GC) region. We assumed that the excess could be imitated by the emission of molecular clouds with depleted density of CRs with energies below ∼10 GeV inside. A novelty of our work is in detailed elaboration of the depletion mechanism of CRs with the mentioned energies through the “barrier” near the cloud edge formed by the self-excited MHD turbulence. This depletion of CRs inside the clouds may be a reason for the deficit of gamma rays from the Central Molecular Zone (CMZ) at energies below a few GeV. This in turn changes the ratio between various emission components at those energies and may potentially absorb the GeV excess by a simple renormalization of key components.

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