Quantum kinetic-equation approach to semiconductor hot-carrier screening

1989 ◽  
Vol 39 (12) ◽  
pp. 8468-8475 ◽  
Author(s):  
Ben Yu-Kuang Hu ◽  
Sanjoy K. Sarker ◽  
John W. Wilkins
Keyword(s):  
Kinetic Equation ◽  
Carrier Screening ◽  
Equation Approach ◽  
Quantum Kinetic Equation ◽  
Hot Carrier

Hot-carrier screening in semiconductors: A Boltzmann-equation approach

1989 ◽  
Vol 39 (12) ◽  
pp. 8464-8467 ◽  
Author(s):  
Ben Yu-Kuang Hu ◽  
John W. Wilkins
Keyword(s):  
Boltzmann Equation ◽  
Carrier Screening ◽  
Equation Approach ◽  
Hot Carrier

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.

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