Particle production, back reaction and singularity avoidance

Pramana ◽  
1999 ◽  
Vol 52 (1) ◽  
pp. 1-17 ◽  
Author(s):  
A. Shaw ◽  
D. Biswas ◽  
B. Modak ◽  
S. Biswas
2012 ◽  
Vol 27 (25) ◽  
pp. 1250150 ◽  
Author(s):  
F. R. KLINKHAMER

A simplified (but consistent) description of particle-production back-reaction effects in de Sitter spacetime is given.


2005 ◽  
Vol 20 (14) ◽  
pp. 1087-1101
Author(s):  
FUAD M. SARADZHEV

The particle production in the self-interacting N-component complex scalar field theory is studied at large N. A non-Markovian source term that includes all higher order back-reaction and collision effects is derived. The kinetic amplitudes accounting for the change in the particle number density caused by collisions are obtained. It is shown that the production of particles is symmetric in the momentum space. The problem of renormalization is briefly discussed.


2016 ◽  
Vol 31 (28) ◽  
pp. 1650160 ◽  
Author(s):  
F. R. Klinkhamer ◽  
G. E. Volovik

The q-theory approach to the cosmological constant problem is reconsidered. The new observation is that the effective classical q-theory gets modified due to the back-reaction of quantum-mechanical particle production by spacetime curvature. Furthermore, a Planck-scale cosmological constant is added to the potential term of the action density, in order to represent the effects from zero-point energies and phase transitions. The resulting dynamical equations of a spatially-flat Friedmann–Robertson–Walker universe are then found to give a steady approach to the Minkowski vacuum, with attractor behavior for a finite domain of initial boundary conditions on the fields. The approach to the Minkowski vacuum is slow and gives rise to an inflation-type increase of the particle horizon.


2017 ◽  
Vol 26 (04) ◽  
pp. 1750028 ◽  
Author(s):  
Eric Greenwood

We investigate both the classical and quantum gravitational collapse of a massive, charged, nonrotating [Formula: see text]-dimensional Bañados–Teitelboim–Zanelli (BTZ)-like domain wall in AdS space. In the classical picture, we show that, as far as the asymptotic observer is concerned, the details of the collapse depend on the amount of charge present in the domain wall; that is, if the domain wall is extremal, nonextremal or overcharged. In both the extremal and nonextremal cases, the collapse takes an infinite amount of observer time to complete. However, in the over-charged case, the collapse never actually occurs, instead one finds an oscillatory solution which prevents the formation of a naked singularity. As far as the infalling observer is concerned, in the nonextremal case, the collapse is completed within a finite amount of proper time. Thus, the gravitational collapse follows that of the typical formation of a black hole via gravitational collapse.Quantum mechanically, we take the absence of induced quasi-particle production and fluctuations of the metric geometry; that is, we ignore the effect of radiation and back-reaction. For the asymptotic observer, we find that, near the horizon, quantization of the domain wall does not allow the formation of the black hole in a finite amount of observer time. For the infalling observer, we are primarily interested in the quantum mechanical effect as the domain wall approaches the classical singularity. In this region, the main result is that the wave function exhibits nonlocal effects, demonstrated by the fact that the Hamiltonian depends on an infinite number of derivatives that cannot be truncated after a finite number of terms. Furthermore, in the large energy density limit, the wave function vanishes at the classical singularity implying that quantization does not rid the black hole of its singularity.


Author(s):  
Philip D. Lunger ◽  
H. Fred Clark

In the course of fine structure studies of spontaneous “C-type” particle production in a viper (Vipera russelli) spleen cell line, designated VSW, virus particles were frequently observed within mitochondria. The latter were usually enlarged or swollen, compared to virus-free mitochondria, and displayed a considerable degree of cristae disorganization.Intramitochondrial viruses measure 90 to 100 mμ in diameter, and consist of a nucleoid or core region of varying density and measuring approximately 45 mμ in diameter. Nucleoid density variation is presumed to reflect varying degrees of condensation, and hence maturation stages. The core region is surrounded by a less-dense outer zone presumably representing viral capsid.Particles are usually situated in peripheral regions of the mitochondrion. In most instances they appear to be lodged between loosely apposed inner and outer mitochondrial membranes.


2009 ◽  
Vol 00 (00) ◽  
pp. 090930024652050-8
Author(s):  
M. Trotta ◽  
R. Cavalli ◽  
C. Trotta ◽  
R. Bussano ◽  
L. Costa

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