Cosmological quark-hadron phase transition and formation of isothermal density fluctuations

The dynamical process of the cosmological quark-hadron phase transition is investigated under the assumption of a weakly first-order phase transition. In particular the characteristic mass of these nuggets is determined to be smaller than 10¹⁹ g, using a spatial correlation function of the trapped quark phase. Furthermore, the possibility of these nuggets being left as isothermal baryonic clouds with very high density (δϱ_b/ϱ_b ∼ 5.0×10¹²) after evaporation is pointed out, and its cosmological implications are discussed.     

Cosmological baryon-number domain structure and the first order phase transition of a vacuum

If CP-nonconservation arises from spontaneous symmetry breaking in the very early universe, the universe will have a domain structure of baryon number. We propose a model of the early universe in which domains are stretched exponentially and the radius of the domains is much greater than that of the horizon of the standard big bang model, provided that the grand unified theory undergoes a first order phase transition. If the size of the stretched domains is sufficiently big to avoid pair annihilations of baryon and antibaryon domains, the difficulties of the baryon symmetric universe may be removed.     

Cosmological Constant and Stability of the Cosmological Models

The importance of cosmological constant for the cosmological models is given. The variations of the cosmological model for parameters λ and k were discussed respectively. Near λ = 0, the cosmological model is unstable with the change of λ, and near λ = β = 0, the cosmological model is unstable with the change of k. So when we consider the stable cosmological model, we must consider the nonzero cosmological constant.     

Cosmological bootstrap

The extremely large value of the cosmological constant that is characteristic of particle physics and the inflation of the early universe are inherently interconnected. One can construct a superpotential that, after consideration for the leading effects due to supergravity, produces a flat potential of inflaton with a constant density of energy V = Λ⁴. The introduction of relatively small quantum loop corrections to the parameters of this superpotential naturally leads to a dynamical instability taking the form of an inflationary regime of relaxation of the cosmological constant. This pattern is phenomenologically consistent with observational data at Λ ∼ 10¹⁶ GeV.     

Cosmological textures

The notions of phase transitions and causality, combined with the standard cosmological model, lead to the appearance of topological defects in the early universe. The most familiar types of defects are solitons, strings, and domain walls. Another type can exist when the spatial universe is compact. When these appear the whole universe takes on a winding number, and the consequences are quite amusing; for example, it is possible that a closed universe can mimic open or flat universes. Another possibility is that the vacuum has a nonabelian magnetic field strength at all points in the universe.This essay received the fifth award from the Gravity Research Foundation for the year 1986-Ed.Work supported by the Department of Energy, contract DE-AC03-76SF00515.     

Cosmological Entanglement

We investigate the connection between the entanglement generated by expanding universe and the cosmological parameters. We show that the faster the universe expands and the larger the total volume results the higher degree of entanglement.     

Cosmological parameters

There is some consensus emerging on the values of the basic parameters of classical cosmology. The baryon number density estimated from the light element abundance or X-ray gas in galaxy clusters tends towards 5% of closure density; the dark matter content based on a number of independent methods appears to be somewhat less than half the closure density; Hubble constant obtained from local measurements, gravitational lens or Sunyaev Zeldovich method are all probably centred around 60 km/sec/Mpc and the age of the Universe is generally agree to be around 14 Gyr — all specified with bearable error bars. The supernova projects and CMBR anisotropy together favour a finite cosmological constant, and gravitational lens statistics support the same conclusion.     

Cosmological neutrino

A brief review of processes occurring at different stages of the evolution of the Universe and influencing the contemporary distribution of the number density of neutrinos is given.     

Cosmological models

An LRS Bianchi type II cosmological model is built with a state equation that is a function of the cosmic timet. The ratiop/ is 1/3 whent 0 and is insignificant whent. Thus, the matter content behaves like radiation for smallt and like dust for larget.     

Viscous Cosmological Model with Variable Gravitational and Cosmological Constants

We have considered some cosmological solutions with variable gravitational and cosmological constants with bulk viscosity. It is found that the solutions are singularity free and the deceleration parameter is in general not a constant unless we assume perfect fluid with equation of state in the standard cosmologies. Moreover, the deceleration parameter is a function of the scale factor and changes sign with evolution, so our solution is a generalization of those obtained by Arbab I. Arbab. The introduction of viscosity not only free from singularity but also give the deceleration parameter a freedom to vary with scale factor. Thus, a viscous cosmological fluid gives a more general situation in the early universe.     

Value of the Cosmological Constant in the Cosmological Relativity Theory

It is shown that the cosmological relativity theory predicts the value = 1.934 × 10^–35s^–2 for the cosmological constant. This value of is in excellent agreement with the measurements recently obtained by the High-Z Supernova Team and the Supernova Cosmology Project.     

Cosmological special relativity

Recently we presented a new special relativity theory for cosmology in which it was assumed that gravitation can be neglected and thus the bubble constant can be taken as a constant. The theory was presented in a six-dimensional hvperspace. three for the ordinary space and three for the velocities. In this paper we reduce our hyperspace to four dimensions by assuming that the three-dimensional space expands only radially, thus one is left with the three dimensions of ordinary space and one dimension of the radial velocity.     

Cosmological Higgs fields

We present a time-dependent solution to the coupled Einstein-Higgs equations for general Higgs-type potentials in the context of flat Friedmann-Robertson-Walker cosmological models. Possible implications are discussed.     

Cosmological dissipative structure

The concept of black hole entropy is generalized to cosmological event horizons. An analogue of the Bekenstein-Hawking generalized second law of thermodynamics is suggested. This law is illustrated by considering entropy changes in various black hole de Sitter spacetimes, and also with the help of a viscous-driven de Sitter universe model, which provides a cosmological version of a far-fromequilibrium dissipative structure. The law apparently fails for some recontractinguniverse models. This indicates that a contribution to the gravitational entropy has been omitted. A possible remedy involving algorithmic complexity theory is suggested. I propose the use of a cosmic entropy censorship hypothesis as a filter for acceptable field theories.     

Cosmological magnetic fields

Magnetic fields are observed not only in stars, but in galaxies, clusters, and even high redshift Lyman-α systems. In principle, these fields could play an important role in structure formation and also affect the anisotropies in the cosmic microwave background radiation (CMB). The study of cosmological magnetic fields aims not only to quantify these effects on large-scale structure and the CMB, but also to answer one of the outstanding puzzles of modern cosmology: when and how do magnetic fields originate? They are either primoridial, i.e. created before the onset of structure formation, or they are generated during the process of structure formation itself.     

Implications of Time Varying Cosmological Constant on Kaluza-Klein Cosmological Model

In this paper, the cosmological model with variable $\varLambda= \alpha \frac{\dot{R}^{2}}{R^{2}} + \beta\frac{1}{R^{2}}$ in Kaluza-Klein metric have been studied. Here α and β are dimensionless parameters. The solutions to Einstein field equations which assume that the Universe is filled with perfect fluid have been obtained by using the Gamma Law Equation p=(γ?1)ρ; in which the parameter γ is constant and power law equation A(t)=R ⁿ (t)—where A(t) is scale factor for extra dimension and R(t) is scale factor for space dimensions. The fifth dimension for the radiation dominated phases is more prominent with this model. Other physical parameters i.e. density, pressure, deceleration parameter, Hubble parameter have been determined for this model. It is observed physical parameters depends upon constants α, β and n. Neo-classical tests have also been studied in this paper.     

Cosmological unparticle correlators

We introduce and study an extension of the correlator of unparticle matter operators in a cosmological environment. Starting from FRW spaces we specialize to a de Sitter space–time and derive its inflationary power spectrum which we find to be almost flat. We finally investigate some consequences of requiring the existence of a unitary boundary conformal field theory in the framework of the dS/CFT correspondence.