scholarly journals Superheavy scalar dark matter from gravitational particle production in α -attractor models of inflation

2021 ◽  
Vol 103 (10) ◽  
Author(s):  
Siyang Ling ◽  
Andrew J. Long
Keyword(s):  
Dark Matter ◽  
Particle Production

scholarly journals Cosmological constant, matter, cosmic inflation and coincidence

2020 ◽  
Vol 35 (15) ◽  
pp. 2050123
Author(s):  
She-Sheng Xue
Keyword(s):  
Dark Matter ◽  
Acoustic Wave ◽  
Cosmological Constant ◽  
Einstein Equation ◽  
Large Scale ◽  
Particle Production ◽  
Cosmological Term ◽  
Coincidence Problem ◽  
Cosmic Inflation ◽  
Cosmic Coincidence Problem

We present a possible understanding to the issues of cosmological constant, inflation, dark matter and coincidence problems based only on the Einstein equation and Hawking particle production. The inflation appears and results agree to observations. The CMB large-scale anomaly can be explained and the dark-matter acoustic wave is speculated. The entropy and reheating are discussed. The cosmological term [Formula: see text] tracks down the matter [Formula: see text] until the radiation-matter equilibrium, then slowly varies, thus the cosmic coincidence problem can be avoided. The relation between [Formula: see text] and [Formula: see text] is shown and can be examined at large redshifts.

scholarly journals Dark Matter Particle Production inb→sTransitions with Missing Energy

2004 ◽  
Vol 93 (20) ◽  
Author(s):  
Chris Bird ◽  
Paul Jackson ◽  
Robert Kowalewski ◽  
Maxim Pospelov
Keyword(s):  
Dark Matter ◽  
Particle Production ◽  
Dark Matter Particle ◽  
Missing Energy

scholarly journals Irreversible Thermodynamic Description of Dark Matter and Radiation Creation during Inflationary Reheating

2017 ◽  
Vol 2017 ◽  
pp. 1-24 ◽  
Author(s):  
Juntong Su ◽  
Tiberiu Harko ◽  
Shi-Dong Liang
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Particle Production ◽  
Thermodynamic Description ◽  
Cosmological Parameters ◽  
Field Energy ◽  
Field Equations ◽  
Matter Creation ◽  
The Universe ◽  
Relativistic Matter

We investigate matter creation processes during the reheating period of the early Universe, by using the thermodynamic of open systems. The Universe is assumed to consist of the inflationary scalar field, which, through its decay, generates relativistic matter and pressureless dark matter. The inflationary scalar field transfers its energy to the newly created matter particles, with the field energy decreasing to near zero. The equations governing the irreversible matter creation are obtained by combining the thermodynamics description of the matter creation and the gravitational field equations. The role of the different inflationary scalar field potentials is analyzed by using analytical and numerical methods. The values of the energy densities of relativistic matter and dark matter reach their maximum when the Universe is reheated up to the reheating temperature, which is obtained as a function of the scalar field decay width, the scalar field particle mass, and the cosmological parameters. Particle production leads to the acceleration of the Universe during the reheating phase, with the deceleration parameter showing complex dynamics. Once the energy density of the scalar field becomes negligible with respect to the matter densities, the expansion of the Universe decelerates, and inflation has a graceful exit.

scholarly journals Search for dark matter produced in association with a leptonically decaying $${\mathrm{Z}} $$ boson in proton–proton collisions at $$\sqrt{s}=13\,\text {Te}\text {V} $$

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
T. Bergauer ◽  
...  
Keyword(s):  
Dark Matter ◽  
Z Boson ◽  
Particle Production ◽  
Direct Detection ◽  
Large Extra Dimensions ◽  
Axial Vector ◽  
Dark Matter Particle ◽  
Higgs Doublet ◽  
Proton Collision ◽  
Proton Proton

AbstractA search for dark matter particles is performed using events with a Z boson candidate and large missing transverse momentum. The analysis is based on proton–proton collision data at a center-of-mass energy of 13$$\,\text {Te}\text {V}$$ Te , collected by the CMS experiment at the LHC in 2016–2018, corresponding to an integrated luminosity of 137$$\,\text {fb}^{-1}$$ fb - 1 . The search uses the decay channels $${\mathrm{Z}} \rightarrow {\mathrm{e}} {\mathrm{e}} $$ Z → e e and $${\mathrm{Z}} \rightarrow {{\upmu }{}{}} {{\upmu }{}{}} $$ Z → μ μ . No significant excess of events is observed over the background expected from the standard model. Limits are set on dark matter particle production in the context of simplified models with vector, axial-vector, scalar, and pseudoscalar mediators, as well as on a two-Higgs-doublet model with an additional pseudoscalar mediator. In addition, limits are provided for spin-dependent and spin-independent scattering cross sections and are compared to those from direct-detection experiments. The results are also interpreted in the context of models of invisible Higgs boson decays, unparticles, and large extra dimensions.

scholarly journals Gravitational waves and dark photon dark matter from axion rotations

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Raymond T. Co ◽  
Keisuke Harigaya ◽  
Aaron Pierce
Keyword(s):  
Dark Matter ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Early Universe ◽  
Radial Direction ◽  
Particle Production ◽  
Baryon Asymmetry ◽  
Complex Field ◽  
Dark Photon ◽  
Pulsar Timing

Abstract An axion rotating in field space can produce dark photons in the early universe via tachyonic instability. This explosive particle production creates a background of stochastic gravitational waves that may be visible at pulsar timing arrays or other gravitational wave detectors. This scenario provides a novel history for dark photon dark matter. The dark photons may be warm at a level detectable in future 21-cm line surveys. For a consistent cosmology, the radial direction of the complex field containing the axion must be thermalized. We explore a concrete thermalization mechanism in detail and also demonstrate how this setup can be responsible for the generation of the observed baryon asymmetry.

Particle production in modified gravity in the early and present day universe

2020 ◽  
Vol 35 (36) ◽  
pp. 2044027
Author(s):  
E. V. Arbuzova
Keyword(s):  
Dark Matter ◽  
Energy Spectrum ◽  
Cosmic Rays ◽  
Modified Gravity ◽  
Particle Production ◽  
Equations Of Motion ◽  
Modified Theories Of Gravity ◽  
Oscillating Solutions ◽  
Theories Of Gravity ◽  
Gravitational Equations

Gravitational equations of motion in modified theories of gravity have oscillating solutions, both in the early and in the present day universe. Particle production by such oscillations is analyzed and possible observational consequences are considered. This phenomenon has impact on energy spectrum of cosmic rays and abundance of dark matter particles.

scholarly journals String fragmentation in supercooled confinement and implications for dark matter

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Iason Baldes ◽  
Yann Gouttenoire ◽  
Filippo Sala
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Particle Production ◽  
Bubble Wall ◽  
Strongly Coupled ◽  
Dark Matter Relic Density ◽  
Relic Density ◽  
Strong Sector ◽  
String Fragmentation ◽  
The Universe

Abstract A strongly-coupled sector can feature a supercooled confinement transition in the early universe. We point out that, when fundamental quanta of the strong sector are swept into expanding bubbles of the confined phase, the distance between them is large compared to the confinement scale. We suggest a modelling of the subsequent dynamics and find that the flux linking the fundamental quanta deforms and stretches towards the wall, producing an enhanced number of composite states upon string fragmentation. The composite states are highly boosted in the plasma frame, which leads to additional particle production through the subsequent deep inelastic scattering. We study the consequences for the abundance and energetics of particles in the universe and for bubble-wall Lorentz factors. This opens several new avenues of investigation, which we begin to explore here, showing that the composite dark matter relic density is affected by many orders of magnitude.

scholarly journals Completely dark photons from gravitational particle production during the inflationary era

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Edward W. Kolb ◽  
Andrew J. Long
Keyword(s):  
Dark Matter ◽  
Vector Field ◽  
Standard Model ◽  
Particle Production ◽  
Number Density ◽  
Massive Vector ◽  
Detailed Consideration ◽  
Electron Volt ◽  
Dark Photon ◽  
Wide Range

Abstract Starting with the de Broglie-Proca Lagrangian for a massive vector field, we calculate the number density of particles resulting from gravitational particle production (GPP) during inflation, with detailed consideration to the evolution of the number density through the reheating. We find plausible scenarios for the production of dark-photon dark matter of mass in a wide range, as low as a micro-electron volt to 1014 GeV. Gravitational particle production does not depend on any coupling of the dark photon to standard-model particles.

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