scholarly journals Relaxation processes in completely ionized plasma in generalized Lorentz model

2018 ◽  
Vol 26 (2) ◽  
pp. 17-28 ◽  
Author(s):  
S. A. Sokolovsky ◽  
A. I. Sokolovsky ◽  
I. S. Kravchuk ◽  
O. A. Grinishin
Keyword(s):  
Kinetic Equation ◽  
Polynomial Approximation ◽  
Electron System ◽  
Relaxation Processes ◽  
Lorentz Model ◽  
The Standard Model ◽  
Temperature Relaxation ◽  
Uniform Case ◽  
Basic Equations ◽  
Relaxation Coefficients

On the basis of the Landau kinetic equation a generalized Lorentz model is proposed, which contrary to the standard model, considers ion system as an equilibrium one. For electron system kinetic equation of the Fokker-Planck type is obtained. In the Bogolyubov method of the reduced description, which is based on his idea of the functional hypothesis, basic equations for electron hydrodynamics construction with account for temperature and macroscopic velocity relaxation processes (kinetic modes of the system) is elaborated. The obtained equations are analyzed near the end of the relaxation processes when the theory has an additional small parameter. The main in small gradients approximation is studied in details, it corresponds to the description of relaxation processes in a spatially uniform case. The obtained equations are approximately solved by the method of truncated expansion in the Sonine polynomials. The velocity and temperature relaxation coefficients are discussed in one- and two-polynomial approximation. As a result the relaxation coefficients are calculated in one-polynomial approximation.

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

Universe ◽  
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.

PRODUCTION OF ELECTRON-POLARIZED BEAMS OF MULTIPLY-CHARGED IONS: THEIR USE IN TESTS OF FUNDAMENTAL ATOMIC PHYSICS

1991 ◽  
Vol 05 (17) ◽  
pp. 1121-1131 ◽  
Author(s):  
C. J. LIU ◽  
R. W. DUNFORD
Keyword(s):  
Atomic Physics ◽  
Electron System ◽  
Multiply Charged Ions ◽  
Polarized Beams ◽  
Electromagnetic Interactions ◽  
Multiply Charged ◽  
Single Electron Capture ◽  
The Standard Model ◽  
Physics Experiments ◽  
Charged Ions

We discuss the prospects for production of an electron-polarized beam of multiply-charged ions by the technique of single-electron capture in a polarized atomic target. In addition, we suggest two atomic physics experiments which could utilize such beams. One of these is a test of the Standard Model of the Weak and Electromagnetic Interactions in a simple one-electron system. The other is a measurement of the hyperfine splitting of the ground state of a multiply-charged lithium-like system.

scholarly journals Релаксация тока в монокристаллах TlGa-=SUB=-1-x-=/SUB=-Dy-=SUB=-x-=/SUB=-Se-=SUB=-2-=/SUB=- (x=0.01; 0.03)

2020 ◽  
Vol 62 (7) ◽  
pp. 1022
Author(s):  
С.Н. Мустафаева ◽  
К.М. Гусейнова ◽  
М.М. Асадов
Keyword(s):  
Low Temperature ◽  
Flight Time ◽  
Charge Carriers ◽  
Physical Parameters ◽  
Relaxation Processes ◽  
Carrier Injection ◽  
Contact Charging ◽  
Deep Traps ◽  
Effective Mobility ◽  
Temperature Relaxation

Abstract The low-temperature relaxation processes in TlGa_1 – _ x Dy_ x Se_2 ( x = 0.01, 0.03) single crystals have been studied experimentally. The physical parameters which characterize the electron processes in Ag–TlGa_1 – _ x Dy_ x Se_2–Ag samples have been determined using the estafette transfer mechanism of the charge formed at deep traps due to the carrier injection from a contact: the effective mobility of the charge transferred due to deep centers, the sample contact capacity, the region of accumulation of the charge in the samples, the contact charging constant, and the flight time of charge carriers through the sample.

scholarly journals Kinetic Equation with Neutrino Oscillations in the Early Universe

1991 ◽  
Vol 44 (6) ◽  
pp. 591 ◽  
Author(s):  
Henry Granek ◽  
Bruce HJ McKellar
Keyword(s):  
Kinetic Equation ◽  
Early Universe ◽  
Neutrino Oscillations ◽  
Chemical Potential ◽  
Electron Neutrino ◽  
Cp Violations ◽  
Chemical Potentials ◽  
The Standard Model ◽  
Parameter Ranges ◽  
The Universe

This paper considers the kinetic equation for interacting neutrino gas in the context of an expanding early universe. It is suggested that if neutrino oscillations are present and CP violations occur prior to the decoupling of the neutrino gas from the rest of the universe, then lepton number may not be conserved and, in principle, significant permanent neutrino chemical potentials may develop and survive until the present day. This would lead to the wen known effect that if the electron neutrino chemical potential is significantly non-zero, then the primordial abundances of the light elements are affected and differ from those of the standard model. Numerical computation is required to examine the parameter ranges leading to a significant non-zero electron neutrino chemical potential.

Thermal Expansion of Amorphous Iron-Chromium-Boron Alloys

1981 ◽  
Vol 8 ◽  
Author(s):  
G. Hunger ◽  
H. W. Bergmann ◽  
B. L. Mordike
Keyword(s):  
Thermal Expansion ◽  
Marked Effect ◽  
Relaxation Processes ◽  
Short Term ◽  
Amorphous Iron ◽  
Chromium Alloys ◽  
Temperature Relaxation ◽  
Expansion Behaviour ◽  
Iron Chromium

ABSTRACTIn amorphous iron-chromium alloys magnetic contraction is superimposed on the thermal expansion. Depending on the proportion of antiferromagnetic chromium the resultant coefficient of expansion is either positiv, negative or zero. The chromium content also changes the Curie temperature. Relaxation processes have a marked effect on the thermal expansion. Long term and short term expansion behaviour was compared and discussed. In addition the crystallization behaviour and mechanical properties of the alloys are reported.

High-temperature relaxation processes in Zn and Fe doped tetragonal YBCO

1994 ◽  
Vol 234 (1-2) ◽  
pp. 91-98 ◽  
Author(s):  
M. Affronte ◽  
C. Nobili ◽  
G. Ottaviani ◽  
F. Licci
Keyword(s):  
High Temperature ◽  
Relaxation Processes ◽  
Temperature Relaxation
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