scholarly journals Mirror dark matter: Cosmology, galaxy structure and direct detection

2014 ◽  
Vol 29 (11n12) ◽  
pp. 1430013 ◽  
Author(s):  
R. Foot
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Initial Conditions ◽  
Direct Detection ◽  
Large Set ◽  
Galaxy Structure ◽  
Unknown Parameters ◽  
Hidden Sector ◽  
Early Universe Cosmology ◽  
Ordinary Particle

A simple way to accommodate dark matter is to postulate the existence of a hidden sector. That is, a set of new particles and forces interacting with the known particles predominantly via gravity. In general, this leads to a large set of unknown parameters, however, if the hidden sector is an exact copy of the standard model sector, then, an enhanced symmetry arises. This symmetry, which can be interpreted as space–time parity, connects each ordinary particle (e, ν, p, n, γ, …) with a mirror partner (e′, ν′, p′, n′, γ′, …). If this symmetry is completely unbroken, then the mirror particles are degenerate with their ordinary particle counterparts, and would interact amongst themselves with exactly the same dynamics that govern ordinary particle interactions. The only new interaction postulated is photon–mirror photon kinetic mixing, whose strength ϵ, is the sole new fundamental (Lagrangian) parameter relevant for astrophysics and cosmology. It turns out that such a theory, with suitably chosen initial conditions effective in the very early universe, can provide an adequate description of dark matter phenomena provided that ϵ~10-9. This review focusses on three main developments of this mirror dark matter theory during the last decade: early universe cosmology, galaxy structure and the application to direct detection experiments.

scholarly journals Gauge-Singlet Vector-Like Fermion Dark Matter, LHC Diphoton Rate, and Direct Detection

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Shrihari Gopalakrishna ◽  
Tuhin Subhra Mukherjee
Keyword(s):  
Dark Matter ◽  
Direct Detection ◽  
Gluon Fusion ◽  
Gauge Bosons ◽  
Hidden Sector ◽  
Dark Matter Relic Density ◽  
Higgs Search ◽  
Matter Model ◽  
Higgs Portal ◽  
Dark Matter Model

We study a gauge-singlet vector-like fermion hidden sector dark matter model, in which the communication between the dark matter and the visible standard model sector is via the Higgs-portal scalar-Higgs mixing and also via a hidden sector scalar with loop-level couplings to two gluons and also to two hypercharge gauge bosons induced by a vector-like quark. We find that the Higgs-portal possibility is stringently constrained to be small by the recent LHC di-Higgs search limits, and the loop induced couplings are important to include. In the model parameter space, we present the dark matter relic density, the dark-matter-nucleon direct detection scattering cross section, the LHC diphoton rate from gluon-gluon fusion, and the theoretical upper bounds on the fermion-scalar couplings from perturbative unitarity.

Application of Differential Evolution in System Identification of Servo-Hydraulic System With a Flexible Load

2006 ◽  
Author(s):  
H. Yousefi ◽  
H. Handroos
Keyword(s):  
System Identification ◽  
Differential Evolution ◽  
Hydraulic System ◽  
Optimization Problems ◽  
Initial Conditions ◽  
Large Set ◽  
Unknown Parameters ◽  
Nonlinear Constraint ◽  
De Algorithm ◽  
Flexible Load

Electro Hydraulic Servo Systems (EHSS) with an asymmetrical cylinder are commonly used in industry. These kinds of systems are nonlinear in nature and their dynamic equations have several unknown parameters. System identification is a prerequisite to analysis of a dynamic system and design of an appropriate controller for improving its performance. In conventional identification methods, a model structure is selected and the parameters of that model are calculated by optimizing an objective function. This process usually requires a large set of input/output data from the system. In addition, the obtained parameters may be only locally optimal. One of the most promising novel evolutionary algorithms is the Differential Evolution (DE) algorithm for solving global optimization problems with continuous parameters. In this article, the DE algorithm is proposed for handling nonlinear constraint functions with boundary limits of variables to find the best parameters of a nonlinear servo-hydraulic system with flexible load. The DE guarantees Fast speed convergence and accurate solutions regardless the initial conditions of parameters. The results suggest that, DE is useful, reliable and easy to use tools in many aspects of control engineering and especially in system identification.

scholarly journals Dark matter-neutrino interconversion at COHERENT, direct detection, and the early Universe

2020 ◽  
Vol 102 (1) ◽  
Author(s):  
Nicholas Hurtado ◽  
Hana Mir ◽  
Ian M. Shoemaker ◽  
Eli Welch ◽  
Jason Wyenberg
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Direct Detection

scholarly journals Early Universe cosmology with mirror dark matter

2010 ◽  
Author(s):  
P. Ciarcelluti ◽  
Jean-Michel Alimi ◽  
André Fuözfa
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Early Universe Cosmology

scholarly journals Self-interacting hidden sector dark matter, small scale galaxy structure anomalies, and a dark force

2021 ◽  
Vol 103 (7) ◽  
Author(s):  
Amin Aboubrahim ◽  
Wan-Zhe Feng ◽  
Pran Nath ◽  
Zhu-Yao Wang
Keyword(s):  
Dark Matter ◽  
Small Scale ◽  
Galaxy Structure ◽  
Hidden Sector ◽  
Dark Force

scholarly journals NEW CONSTRAINTS ON DARK MATTER FROM CMS AND ATLAS DATA

2011 ◽  
Vol 26 (21) ◽  
pp. 1521-1535 ◽  
Author(s):  
SUJEET AKULA ◽  
DANIEL FELDMAN ◽  
ZUOWEI LIU ◽  
PRAN NATH ◽  
GREGORY PEIM
Keyword(s):  
Dark Matter ◽  
Supergravity Models ◽  
Early Universe ◽  
Direct Detection ◽  
Mass Region ◽  
Atlas Data ◽  
Minimal Supergravity ◽  
Relic Density ◽  
Neutralino Mass ◽  
Focus Point

Constraints on dark matter from the first CMS and ATLAS SUSY searches are investigated. It is shown that within the minimal supergravity model, the early search for supersymmetry at the LHC has depleted a large portion of the signature space in dark matter direct detection experiments. In particular, the prospects for detecting signals of dark matter in the XENON and CDMS experiments are significantly affected in the low neutralino mass region. Here the relic density of dark matter typically arises from slepton coannihilations in the early universe. In contrast, it is found that the CMS and ATLAS analyses leave untouched the Higgs pole and the Hyperbolic Branch/Focus Point regions, which are now being probed by the most recent XENON results. Analysis is also done for supergravity models with non-universal soft breaking where one finds that a part of the dark matter signature space depleted by the CMS and ATLAS cuts in the minimal SUGRA case is repopulated. Thus, observation of dark matter in the LHC depleted region of minimal supergravity may indicate non-universalities in soft breaking.

scholarly journals The impact of inelastic self-interacting dark matter on the dark matter structure of a Milky Way halo

2020 ◽  
Author(s):  
Kun Ting Eddie Chua ◽  
Karia Dibert ◽  
Mark Vogelsberger ◽  
Jesús Zavala
Keyword(s):  
Dark Matter ◽  
High Speed ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Direct Detection ◽  
Major Axis ◽  
Inelastic Collisions ◽  
Axis Ratio ◽  
Lower Velocity ◽  
The Impact

Abstract We study the effects of inelastic dark matter self-interactions on the internal structure of a simulated Milky Way (MW)-size halo. Self-interacting dark matter (SIDM) is an alternative to collisionless cold dark matter (CDM) which offers a unique solution to the problems encountered with CDM on sub-galactic scales. Although previous SIDM simulations have mainly considered elastic collisions, theoretical considerations motivate the existence of multi-state dark matter where transitions from the excited to the ground state are exothermic. In this work, we consider a self-interacting, two-state dark matter model with inelastic collisions, implemented in the Arepo code. We find that energy injection from inelastic self-interactions reduces the central density of the MW halo in a shorter timescale relative to the elastic scale, resulting in a larger core size. Inelastic collisions also isotropize the orbits, resulting in an overall lower velocity anisotropy for the inelastic MW halo. In the inner halo, the inelastic SIDM case (minor-to-major axis ratio s ≡ c/a ≈ 0.65) is more spherical than the CDM (s ≈ 0.4), but less spherical than the elastic SIDM case (s ≈ 0.75). The speed distribution f(v) of dark matter particles at the location of the Sun in the inelastic SIDM model shows a significant departure from the CDM model, with f(v) falling more steeply at high speeds. In addition, the velocity kicks imparted during inelastic collisions produce unbound high-speed particles with velocities up to 500 km s−1 throughout the halo. This implies that inelastic SIDM can potentially leave distinct signatures in direct detection experiments, relative to elastic SIDM and CDM.

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