scholarly journals Particle number and current in Dirac field in the closed universe

1970 ◽  
Vol 9 (9) ◽  
pp. 4-7
Author(s):  
PR Dhungel ◽  
U Khanal
Keyword(s):  
Particle Number ◽  
Particle Number Density ◽  
Dirac Field ◽  
Closed Universe ◽  
Frw Universe ◽  
Frw Model ◽  
The Universe ◽  
Particle Current ◽  
Massless Fields ◽  
Finite Particle

The behavior of the particle number and particle current of the free Dirac field in the closed FRW universe has been explored. Although the particle number is conserved for the massless fields as expected, it is not for the massive ones. So, there is a finite particle current in any finite sized volume of the universe. Such currents tend to enhance the density contrast over time. It is seen that the momenta of the Dirac particle is quantized in a closed FRW model. The particles distribute themselves in such a way as to resemble that required for the flattened rotation curves of galaxies. Key words: Closed Universe; Dirac field; Comoving particle number density DOI: http://dx.doi.org/10.3126/sw.v9i9.5508 SW 2011; 9(9): 4-7

Dark matter as residual of topological changes

2016 ◽  
Vol 13 (03) ◽  
pp. 1650027
Author(s):  
Cécile Barbachoux ◽  
Joseph Kouneiher
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Particle Number ◽  
Particle Number Density ◽  
Number Density ◽  
Quantum Regime ◽  
Extended Group ◽  
The Universe ◽  
Spacetime Foam ◽  
Finite Particle

We investigate in this paper the possibilities that the observed cold dark matter density can be generated by decays of a heavy scalar field which dominate the universe at the quantum regime. Indeed, we present two approaches based on an extension of quantum field theory to the case when spacetime topology fluctuates (spacetime foam, at the quantum regime). In this extension the number of bosonic fields becomes a variable and the ground state is characterized by a finite particle number density. In the second approach it is the gauge-group parameters which became dynamical. This is tributary on the Centrally Extended Group and Cohomology.

scholarly journals A CAUSAL MODEL FOR A CLOSED UNIVERSE

2004 ◽  
Vol 13 (05) ◽  
pp. 871-883
Author(s):  
MAURICIO CATALDO ◽  
SERGIO DEL CAMPO ◽  
PAUL MINNING ◽  
FRANCISCO PEÑA
Keyword(s):  
Viscous Fluid ◽  
Entropy Production ◽  
Causal Model ◽  
Closed Universe ◽  
Frw Universe ◽  
Dynamical Equations ◽  
Closed Model ◽  
The Universe ◽  
Friedmann Robertson Walker ◽  
Causal Thermodynamics

We study a closed model of a universe filled with viscous fluid and quintessence matter components. The dynamical equations imply that the universe might look like an accelerated flat Friedmann–Robertson–Walker (FRW) universe at low redshift. We consider here dissipative processes which obey a causal thermodynamics. Here, we account for the entropy production via causal dissipative inflation.

scholarly journals Particle Creation and Thermal Aspects of Viscous Generalized Cosmic Chaplygin Gas

Symmetry ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1039
Author(s):  
Abdul Jawad ◽  
Shamaila Rani ◽  
M. Adeel Sultan
Keyword(s):  
Particle Number ◽  
Particle Creation ◽  
Second Law Of Thermodynamics ◽  
Particle Number Density ◽  
Chaplygin Gas ◽  
Frw Universe ◽  
Generalized Second Law ◽  
Thermal Equilibrium Condition ◽  
Generalized Cosmic Chaplygin Gas ◽  
Creation Rate

We investigate the particle creation, as well as the thermodynamics phenomenon of viscous generalized cosmic Chaplygin gas as a cosmic fluid by assuming the flat FRW universe. For this purpose, we extract various parameters such as the energy density ( ρ ) , Hubble parameter ( H ) , declaration parameter ( q ) , temperature ( T f ) , and particle number density ( n ) in the presence of three different models of the particle creation rate ( Γ ). We discuss the validity of the generalized second law of thermodynamics and thermal equilibrium condition under three models of Γ and discuss the graphical behavior of above-mentioned terms.

scholarly journals ACCELERATION OF THE UNIVERSE DRIVEN BY THE CASIMIR FORCE

2008 ◽  
Vol 17 (02) ◽  
pp. 343-366 ◽  
Author(s):  
MAREK SZYDŁOWSKI ◽  
WŁODZIMIERZ GODŁOWSKI
Keyword(s):  
Casimir Force ◽  
Initial Conditions ◽  
Casimir Effect ◽  
Information Criterion ◽  
Casimir Energy ◽  
Information Criteria ◽  
Frw Universe ◽  
Λcdm Model ◽  
Frw Model ◽  
The Universe

We investigate an evolutional scenario of the FRW universe with the Casimir energy scaling like (-)(1 + z)4. The Casimir effect is used to explain the vacuum energy differences (its value measured in astrophysics is very small compared to the value obtained from quantum-field-theory calculations). The dynamics of the FRW model is represented in terms of a two-dimensional dynamical system to show all evolutional paths of this model in the phase space for all admissible initial conditions. We find also an exact solution for nonflat evolutional paths of the Universe driven by the Casimir effect. The main difference between the FRW model with the Casimir force and the ΛCDM model is that their generic solutions are a set of evolutional paths with a bounce solution and an initial singularity, respectively. The evolutional scenario is tested by using the SNIa data, FRIIb radiogalaxies, baryon oscillation peak and CMB observation. We compare the power of explanation of the model considered and the ΛCDM model using the Bayesian information criterion and the Bayesian factor. Our investigation of the information criteria of model selection showed preference for the ΛCDM model over other models considered. However, the presence of the negative-like radiation term can remove a tension between the theoretical and the observed primordial 4 He and D abundance.

scholarly journals Distribution of energy density of Dirac field in the closed universe

1970 ◽  
Vol 9 (9) ◽  
pp. 1-3
Author(s):  
SK Sharma ◽  
U Khanal
Keyword(s):  
Energy Density ◽  
Finite Energy ◽  
Negative Energy ◽  
Field Energy ◽  
Dirac Field ◽  
Closed Universe ◽  
Frw Universe ◽  
Energy Current ◽  
Large Structures ◽  
Energy Flows

The behavior of the energy of the free Dirac field in the closed FRW universe has been looked at. It is generally expected that the comoving energy density for the particles is conserved. Although this expectation is true for the massless fields, it is not for the massive ones. So, there is a finite energy current in any finite sized volume of the universe. The energy current is positive throughout for lowest state, n = 0. For n = 1, however, there occurs negative energy flow near r = π/2. So energy flows out of the region. It may be expected that the two regions, on either sides may become disjoint over time, but this can be confirmed only after studying the time evolution. If confirmed, this could explain the process of fragmentation of large structures. Larger n appears to produce larger number of such density contrasts. Key words: Closed Universe; Dirac field; Energy DensityDOI: http://dx.doi.org/10.3126/sw.v9i9.5492SW 2011; 9(9): 1-3

Experimentally determined particle number density statistics in an industrial-scale, pulverized-coal-fired boiler

1993 ◽  
Vol 7 (6) ◽  
pp. 842-851 ◽  
Author(s):  
M. Queiroz ◽  
M. P. Bonin ◽  
J. S. Shirolkar ◽  
R. W. Dawson
Keyword(s):  
Particle Number ◽  
Particle Number Density ◽  
Pulverized Coal ◽  
Industrial Scale ◽  
Number Density

The next step in precipitation polymerization of N-isopropylacrylamide: particle number density control by monochain globule surface charge modulation

2016 ◽  
Vol 7 (32) ◽  
pp. 5123-5131 ◽  
Author(s):  
O. L. J. Virtanen ◽  
M. Brugnoni ◽  
M. Kather ◽  
A. Pich ◽  
W. Richtering
Keyword(s):  
Particle Size ◽  
Robust Control ◽  
Surface Charge ◽  
Particle Number ◽  
Particle Number Density ◽  
Precipitation Polymerization ◽  
Number Density ◽  
Density Control ◽  
Charge Modulation

Many applications of poly(N-isopropylacrylamide) microgels necessitate robust control over particle size.

scholarly journals Almost-Pseudo-Ricci Symmetric FRW Universe with a Dynamic Cosmological Term and Equation of State

Universe ◽  
2021 ◽  
Vol 7 (7) ◽  
pp. 205
Author(s):  
Sanjay Mandal ◽  
Avik De ◽  
Tee-How Loo ◽  
Pradyumn Kumar Sahoo
Keyword(s):  
Equation Of State ◽  
Cosmological Parameters ◽  
Cosmological Term ◽  
Ricci Scalar ◽  
Energy Conditions ◽  
Late Time ◽  
Frw Universe ◽  
Accelerating Expansion ◽  
Expansion Of The Universe ◽  
The Universe

The objective of the present paper is to investigate an almost-pseudo-Ricci symmetric FRW spacetime with a constant Ricci scalar in a dynamic cosmological term Λ(t) and equation of state (EoS) ω(t) scenario. Several cosmological parameters are calculated in this setting and thoroughly studied, which shows that the model satisfies the late-time accelerating expansion of the universe. We also examine all of the energy conditions to check our model’s self-stability.

Effect of Particle Number Density on Wave Dispersion in a Two-Dimensional Yukawa System

2017 ◽  
Vol 34 (7) ◽  
pp. 075203
Author(s):  
Rang-Yue Zhang ◽  
Yan-Hong Liu ◽  
Feng Huang ◽  
Zhao-Yang Chen ◽  
Chun-Yan Li
Keyword(s):  
Particle Number ◽  
Wave Dispersion ◽  
Particle Number Density ◽  
Two Dimensional ◽  
Number Density

scholarly journals RADION POTENTIAL AND BRANE DYNAMICS

2001 ◽  
Vol 16 (24) ◽  
pp. 1583-1595 ◽  
Author(s):  
L. MERSINI
Keyword(s):  
Inflation Rate ◽  
Vacuum Energy ◽  
Density Perturbation ◽  
Scalar Fields ◽  
Fine Tuning ◽  
Late Time ◽  
Frw Universe ◽  
Strong Suppression ◽  
Dynamic Setting ◽  
The Universe

We examine the cosmology of Randall–Sundrum model in a dynamic setting where scalar fields are present in the bulk as well as the branes. This generates a mechanism similar to that of Goldberger–Wise for radion stabilization and the recovery of late-time cosmology features on the branes. Due to the induced radion dynamics, the inflating branes roll towards the minimum of the radion potential, thereby exiting inflation and reheating the universe. In the slow roll part of the potential, the TeV branes have maximum inflation rate and energy as their coupling to the radion and bulk modes have minimum suppression. Hence, when rolling down the steep end of the potential towards the stable point, the radion field (which appears as the inflaton of the effective 4-D theory in the branes) decays very fast and reheats the universe. This process results in a decrease of the brane's canonical vacuum energy, Λ4. However, at the minimum of the potential Λ4 is small but not necessarily zero and the fine-tuning issue remains. Density perturbation constraints introduce an upper bound on Λ4. Due to the large radion mass and strong suppression to the bulk modes, moduli problems and bulk reheating do not occur. The reheat temperature and a sufficient number of e-folding constraints for the brane-universe are also satisfied. The model therefore recovers the radiation dominated FRW universe.

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