Coleman-Weinberg theory and the new inflationary universe scenario

It is argued that a new inflationary universe scenario, which provides a possible solution of the horizon, flatness, homogeneity, isotropy and primordial monopole problems, can be naturally implemented in the context of grand unified theories of the type of the Coleman-Weinberg theory.     

Scalar field fluctuations in the expanding universe and the new inflationary universe scenario

The behaviour of the scalar fied fluctuations in the exponentially expanding universe and their role in the new inflationary universe scenario are investigated.     

Photon-electron scattering taking vacuum energy into account

We deal with photon-electron scattering between the two uncharged conducting parallel plates. The electromagnetic vacuum field between the two plates is defined by the configuration of space and also interacts with the electrons. We first deal with the relevant operators for the electron and photon fields and with the Feynman propagator. We compute theS-matrix for photon-electron scattering, taking into account the influence of the vacuum field. The computed photon-electron scattering cross section also manifests the influence of the vacuum field. We give an example for low-energy scattering of the influence of the vacuum field upon the scattering cross section.     

An interacting dark energy model in a non-flat universe

In this paper, an interacting dark energy model in a non-flat universe is studied, with taking interaction form $C=\alpha H\rho _{de}$ C = α H ρ d e . And in this study a property for the mysterious dark energy is aforehand assumed, i.e. its equation of state $w_{\Lambda }=-1$ w Λ = - 1 . After several derivations, a power-law form of dark energy density is obtained $\rho _{\Lambda } \propto a^{-\alpha }$ ρ Λ ∝ a - α , here $a$ a is the cosmic scale factor, $\alpha $ α is a constant parameter introducing to describe the interaction strength and the evolution of dark energy. By comparing with the current cosmic observations, the combined constraints on the parameter $\alpha $ α is investigated in a non-flat universe. For the used data they include: the Union2 data of type Ia supernova, the Hubble data at different redshifts including several new published datapoints, the baryon acoustic oscillation data, the cosmic microwave background data, and the observational data from cluster X-ray gas mass fraction. The constraint results on model parameters are $\Omega _{K}=0.0024\,(\pm 0.0053)^{+0.0052+0.0105}_{-0.0052-0.0103}, \alpha =-0.030\,(\pm 0.042)^{+0.041+0.079}_{-0.042-0.085}$ Ω K = 0.0024 ( ± 0.0053 ) - 0.0052 - 0.0103 + 0.0052 + 0.0105 , α = - 0.030 ( ± 0.042 ) - 0.042 - 0.085 + 0.041 + 0.079 and $\Omega _{0m}=0.282\,(\pm 0.011)^{+0.011+0.023}_{-0.011-0.022}$ Ω 0 m = 0.282 ( ± 0.011 ) - 0.011 - 0.022 + 0.011 + 0.023 . According to the constraint results, it is shown that small constraint values of $\alpha $ α indicate that the strength of interaction is weak, and at $1\sigma $ 1 σ confidence level the non-interacting cosmological constant model can not be excluded.     

An improvement of the Peierls equation by taking into account the lattice effects

An improvement of the Peierls equation has been made by including the lattice effects. By using the non-trivially gluing mechanism for the simple cubic lattice, in which atoms interact with its first and second nearest neighbours through a central force, the dislocation equation has been derived rigorously for the isotropic case. In the slowly varying approximation, the Peierls equation with the improvement by including the lattice effects has been obtained explicitly. The new equation can be used to substitute for the old one in theoretical investigations of dislocations. The major change of the predicted dislocation structure is in the core region. The width of the dislocation given by using the new equation is about three times that given by the classical Peierls--Nabarro theory for the simple cubic lattice.     

Fluctuations in the inflationary universe

In the usual treatment of the inflationary universe, it is assumed that the expectation value of some component of the Higgs field develops a non-zero symmetry breaking value Φ₀. However, in the models normally considered, the expectation value of Φ will be zero at all times because Φ and ?Φ are equally probable. To overcome this difficulty, we calculate the effective action as a function of 〈Φ²〉 rather than 〈Φ〉. This also solves the infra-red problem associated with a Coleman-Weinberg condition in de Sitter space. The expectation value of Φ² grows linearly with time at first and then as (t₂ ? t^?1). The irregularities in the resulting universe are smaller than those predicted by previous authors, though in the case of the standard SU(5) GUT they are still bigger than the limit set by the microwave background.     

Calculation of energy characteristics of the metal surface taking into account the lattice relaxation effects

Within the framework of the electron-density functional theory method, a self-consistent calculation of the shift of two near-surface ionic planes in different metals has been carried out. The effect of the near-surface lattice relaxation on the surface energy of metals and on the electron work function from these metallic surfaces has been investigated. To describe the arising strong inhomogeneity of the electronic system in the near-surface region, gradient corrections have been taken into account for the kinetic and exchange-correlation energy. To calculate the effect of electron-ion interaction on the energy characteristics of the surface, the Heine-Abarenkov pseudopotential has been used.     

第三讲宇宙中的暗物质和暗能量

文章对暗物质粒子的候选者和宇宙中暗能量的研究现状作一简单介绍．     

第三讲 宇宙中的暗物质和暗能量

文章对暗物质粒子的候选者和宇宙中暗能量的研究现状作一简单介绍.     

Holographic dark energy in a cyclic universe

In this paper we study the cosmological evolution of the holographic dark energy in a cyclic universe, generalizing the model of holographic dark energy proposed by Li. The holographic dark energy with c<1 can realize a quintom behavior; namely, it evolves from a quintessence-like component to a phantom-like one. The holographic phantom energy density grows rapidly and dominates the late-time expanding phase, helping to realize a cyclic universe scenario in which the high energy regime is modified by the effects of quantum gravity, causing a turn-around (and a bounce) of the universe. The dynamical evolution of holographic dark energy in the regimes of low energy and high energy is governed by two differential equations, respectively. It is of importance to link the two regimes for this scenario. We propose a link condition giving rise to a complete picture of holographic evolution of a cyclic universe.     

Cosmological perturbations in the inflationary universe

In the framework of the gauge-invariant formalism the problem of the evolution of adiabatic perturbations in the metric for the theory of gravity with higher derivatives, which contains inflation, has been solved. The results are compared with the case when inflation arises due to a scalar field. The restrictions on the parameters of the models are given.     

Baryon asymmetry in the inflationary universe

It is shown that the baryon asymmetry in the inflationary universe under certain constraints on the masses of superheavy bosons can be larger than that in the standard baryosynthesis scenario. An important property of the model considered is that the final baryon asymmetry does not depend on initial conditions in the early universe in contrast to what occurs in the standard scenario based on B?L conserving GUTs.     

Interacting ghost dark energy in non-flat universe

A new dark energy model called “ghost dark energy” was recently suggested to explain the observed accelerating expansion of the universe. This model originates from the Veneziano ghost of QCD. The dark energy density is proportional to Hubble parameter, ρ _D  = α H, where α is a constant of order L_QCD³{\Lambda_{\rm QCD}^3} and Λ_QCD ~ 100 MeV is QCD mass scale. In this Letter, we extend the ghost dark energy model to the universe with spatial curvature in the presence of interaction between dark matter and dark energy. We study cosmological implications of this model in detail. In the absence of interaction the equation of state parameter of ghost dark energy is always w _D > −1 and mimics a cosmological constant in the late time, while it is possible to have w _D < −1 provided the interaction is taken into account. When k = 0, all previous results of ghost dark energy in flat universe are recovered. For the observational test, we use Supernova type Ia Gold sample, shift parameter of cosmic microwave background radiation and the correlation of acoustic oscillation on the last scattering surface and the baryonic acoustic peak from Sloan Digital Sky Survey are used to confine the value of free parameter of mentioned model.     

Dark matter and dark energy of the universe

A possibility of existing spheres filled with a uniform constant scalar field in the Universe is shown. These spheres can act as “dark matter” and can be responsible for a decreasing behavior of the “ rotational” curved galaxies observed. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 9–19, April, 2006.     

A new inflationary universe scenario: A possible solution of the horizon,flatness, homogeneity,isotropy and primordial monopole problems

A new inflationary universe scenario is suggested, which is free of the shortcomings of the previous one and provides a possible solution of the horizon, flatness, homogeneity and isotropy problems in cosmology, and also a solution of the primordial monopole problem in grand unified theories.     

Holographic dark energy and the universe expansion acceleration

By incorporating the holographic principle in a time-depending Λ-term cosmology, new physical bounds on the arbitrary parameters of the model can be obtained. Considering then the dark energy as a purely geometric entity, for which no equation of state has to be introduced, it is shown that the resulting range of allowed values for the parameters may explain both the coincidence problem and the universe accelerated expansion, without resorting to any kind of additional structures.     

Quantum fluctuations in the new inflationary universe

The evolution of quantum fluctuations of a scalar field in de Sitter space is analyzed in the context of the new inflationary scenario. The duration of the inflationary phase is estimated and the problem of density perturbations resulting from quantum fluctuations of the Higgs field is discussed.     

Fate of order parameter in the inflationary universe

We evaluate the friction term of the evolution equation of the order parameter in the new inflationary universe scenario. It is shown that the friction force is too weak so that the order parameter travels many time around minima of the Coleman-Weinberg potential. It causes unwanted large scale inhomogeneities. Reheating of the universe is also discussed.     

Effects of quantum gravity on the inflationary parameters and thermodynamics of the early universe

The effects of generalized uncertainty principle (GUP) on the inflationary dynamics and the thermodynamics of the early universe are studied. Using the GUP approach, the tensorial and scalar density fluctuations in the inflation era are evaluated and compared with the standard case. We find a good agreement with the Wilkinson Microwave Anisotropy Probe data. Assuming that a quantum gas of scalar particles is confined within a thin layer near the apparent horizon of the Friedmann-Lemaitre-Robertson-Walker universe which satisfies the boundary condition, the number and entropy densities and the free energy arising form the quantum states are calculated using the GUP approach. A qualitative estimation for effects of the quantum gravity on all these thermodynamic quantities is introduced.