Transverse radius of an expanding hadronic system at freeze-out time

1989 ◽  
Vol 40 (5) ◽  
pp. 2107-2113
Author(s):  
Mark L. Tincknell
Keyword(s):  
Hadronic System ◽  
Freeze Out

scholarly journals Gravitational wave signals of dark matter freeze-out

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Danny Marfatia ◽  
Po-Yan Tseng
Keyword(s):  
Phase Transition ◽  
Dark Matter ◽  
Gravitational Waves ◽  
Order Phase Transition ◽  
First Order ◽  
Stochastic Background ◽  
First Order Phase Transition ◽  
Relic Abundance ◽  
First Order Phase ◽  
Freeze Out

Abstract We study the stochastic background of gravitational waves which accompany the sudden freeze-out of dark matter triggered by a cosmological first order phase transition that endows dark matter with mass. We consider models that produce the measured dark matter relic abundance via (1) bubble filtering, and (2) inflation and reheating, and show that gravitational waves from these mechanisms are detectable at future interferometers.

scholarly journals Dark Matter Freeze-Out via Catalyzed Annihilation

2021 ◽  
Vol 127 (6) ◽  
Author(s):  
Chuan-Yang Xing ◽  
Shou-hua Zhu
Keyword(s):  
Dark Matter ◽  
Freeze Out

scholarly journals Analyzing Transverse Momentum Spectra of Pions, Kaons and Protons in p–p, p–A and A–A Collisions via the Blast-Wave Model with Fluctuations

Entropy ◽  
2021 ◽  
Vol 23 (7) ◽  
pp. 803
Author(s):  
Hai-Ling Lao ◽  
Fu-Hu Liu ◽  
Bo-Qiang Ma
Keyword(s):  
Transverse Momentum ◽  
Flow Velocity ◽  
Blast Wave ◽  
Proper Time ◽  
Wave Model ◽  
Transverse Flow ◽  
Momentum Spectra ◽  
Transverse Momentum Spectra ◽  
Transverse Flow Velocity ◽  
Freeze Out

The transverse momentum spectra of different types of particles, π±, K±, p and p¯, produced at mid-(pseudo)rapidity in different centrality lead–lead (Pb–Pb) collisions at 2.76 TeV; proton–lead (p–Pb) collisions at 5.02 TeV; xenon–xenon (Xe–Xe) collisions at 5.44 TeV; and proton–proton (p–p) collisions at 0.9, 2.76, 5.02, 7 and 13 TeV, were analyzed by the blast-wave model with fluctuations. With the experimental data measured by the ALICE and CMS Collaborations at the Large Hadron Collider (LHC), the kinetic freeze-out temperature, transverse flow velocity and proper time were extracted from fitting the transverse momentum spectra. In nucleus–nucleus (A–A) and proton–nucleus (p–A) collisions, the three parameters decrease with the decrease of event centrality from central to peripheral, indicating higher degrees of excitation, quicker expansion velocities and longer evolution times for central collisions. In p–p collisions, the kinetic freeze-out temperature is nearly invariant with the increase of energy, though the transverse flow velocity and proper time increase slightly, in the considered energy range.

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.

scholarly journals FUGACITY AND REHEATING OF PRIMORDIAL NEUTRINOS

2013 ◽  
Vol 28 (40) ◽  
pp. 1350188 ◽  
Author(s):  
JEREMIAH BIRRELL ◽  
CHENG-TAO YANG ◽  
PISIN CHEN ◽  
JOHANN RAFELSKI
Keyword(s):  
Cosmological Model ◽  
Background Radiation ◽  
Chemical Nonequilibrium ◽  
Model Parameter ◽  
Standard Cosmological Model ◽  
Cmb Fluctuations ◽  
The Impact ◽  
Freeze Out

We clarify in a quantitative way the impact that distinct chemical Tc and kinetic Tk freeze-out temperatures have on the reduction of the neutrino fugacity ϒν below equilibrium, i.e. ϒν<1, and the increase of the neutrino temperature Tν via partial reheating. We establish the connection between ϒν and Tk via the modified reheating relation Tν(ϒν)/Tγ, where Tγ is the temperature of the background radiation. Our results demonstrate that one must introduce the chemical nonequilibrium parameter, i.e. the fugacity, ϒν, as an additional standard cosmological model parameter in the evaluation of CMB fluctuations as its value allows measurement of Tk.

Spontaneous symmetry breaking and the local freeze-out inTl2+-doped KH2AsO4

1982 ◽  
Vol 25 (1) ◽  
pp. 311-318 ◽  
Author(s):  
G. M. Ribeiro ◽  
L. V. Gonzaga ◽  
A. S. Chaves ◽  
R. Gazzinelli ◽  
R. Blinc ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Freeze Out
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