Pulsed Cathodoluminescence of Single-Crystalline and Pressed CaF2:Yb2+,Yb3+
Автор(ы): Korepanov V. I.*Bekmyrza K. Zh.*Lisitsyn V. M.*Garibin E. A.*Gusev P. E.*Demidenko A. A.*Krutov M. A.*Mironovc I. A.*Reiterov V. M.*Baktybekov K. S.*
Ключевые слова: модели космологические*вселенные узлы*полосы Мобиуса*космические микроволновые излучения*
Реферат: We investigate the trefoil and figure-eight knot universes from Bianchi-type I cosmology. In particular, we construct several concrete models describing the knot universes related to the cyclic universe and examine those cosmological features and properties in detail. Finally some examples of unknotted closed curves solutions (spiky and Mobius strip universes) are presented.
F(T) gravity and k-essence
Автор(ы): Мырзакулов Р.*
Объем документа:
МРНТИ: 41.29.25
Ключевые слова: теория гравитации*космология*темная энергия*модели космологические*
Реферат: This a brief review on F(T) gravity and its relation with k-essence. Modified teleparallel gravity theory with the torsion scalar has recently gained a lot of attention as a possible explanation of dark energy. We perform a thorough reconstruction analysis on the so-called F(T) models, where F(T) is some general function of the torsion term, and deduce the required conditions for the equivalence between of F(T) models with pure kinetic k-essence models. We present a new class of models of F(T)-gravity and k-essence.
Accelerating universe from F(T) gravities
Автор(ы): Мырзакулов Р.*
Объем документа: С. 1752-1760
МРНТИ: 41.29.25
Ключевые слова: теория гравитации*космология*ускорение вселенной*модели гравитации*
Реферат: It is shown that the acceleration of the universe can be understood by considering a F(T) gravity models. For these F(T) gravity models, a variant of the accelerating cosmology reconstruction program is developed. Some explicit examples of F(T) are reconstructed from the background FRW expansion history.
Einstein-Cartan gravity with scalar-fermion interactions
Автор(ы): Мырзакулов Р.*
Объем документа: С. 47-50
МРНТИ: 41.29.25
Ключевые слова: теория Эйнштейна - Картена*космология*расширение вселенной*модели космологические*
Реферат: In this paper, we have considered the g-essence and its particular cases, k-essence and f-essence, within the framework of the Einstein-Cartan theory. We have shown that a single fermionic field can give rise to the accelerated expansion within the Einstein-Cartan theory. The exact analytical solution of the Einstein-Cartan-Dirac equations is found. This solution describes the accelerated expansion of the Universe with the equation of state parameter w = ?1 as in the case of ?CDM model.
Реферат: In this paper, following the simple proposal by He and Ma for quantization of a black hole (BH) using Bohr\'s method, we discuss the solvability of the wave equation for such a BH. We consequentially solve the associated Schrodinger equation. The eigenfunction problem reduces to the Heun B, H, differential equation, which is a natural generalization of the hypergeometric differential equation. We investigate some physical properties of the wavefunction. We then obtain the expectation value of the kinetic and the potential energies, using Hellmann-Feynman theorem. Our work introduces some new applications of the Heun function.
Entropic corrections to Newton\'s law
Автор(ы): Мырзакулов Р.*
Объем документа:
МРНТИ: 41.29.25
Ключевые слова: обобщенный принцип неуверенности*гравитационная формула Ньютона*энтропия*гравитация*
Реферат: In this short paper, we calculate separately the generalized uncertainty principle (GUP) and self-gravitational corrections to Newton\'s gravitational formula. We show that for a complete description of the GUP and self-gravity effects, both the temperature and entropy must be modified.
Reconstruction of f(T) gravity: Rip cosmology, finite-time future singularities, and thermodynamics
Реферат: We demonstrate that there appear finite-time future singularities in f(T) gravity with T being the torsion scalar. We reconstruct a model of f(T) gravity with realizing the finite-time future singularities. In addition, it is explicitly shown that a power-law-type correction term such as a T2 term can remove the finite-time future singularities in f(T) gravity. Moreover, we study f(T) models with realizing inflation in the early universe, the ?CDM model, little rip cosmology and pseudo-rip cosmology. It is demonstrated that the disintegration of bound structures for little rip and pseudo-rip cosmologies occurs in the same way as in gravity with corresponding dark energy fluid. We also discuss that the time-dependent matter instability in the star collapse can occur in f(T) gravity. Furthermore, we explore thermodynamics in f(T) gravity and illustrate that the second law of thermodynamics can be satisfied around the finite-time future singularities for the universe with the temperature inside the horizon being the same as that of the apparent horizon.
Reconstruction of some cosmological models in f(R,T) cosmology
Реферат: In this paper, we reconstruct cosmological models in the framework of f(R,T) gravity, where R is the Ricci scalar and T is the trace of the stress-energy tensor. We show that the dust fluid reproduces /\CDM, phantom-non-phantom era and phantom cosmology. Further, we reconstruct different cosmological models, including the Chaplygin gas, and scalar field with some specific forms of f(R,T). Our numerical simulation for the Hubble parameter shows good agreement with the BAO observational data for low redshifts, z<2.