A short introduction to Weyl geometry and Weyl gravity is given. The self-consistency relation for the variation of the general form of the matter action integral to be conformal invariant is obtained. It is shown that the particle production rate per unit coordinate volume per unit coordinate time is conformal invariant. It is noticed that such a feature allows us to consider the perfect...
The geodesic deviation equation
$\frac{D^2\xi^{\mu}}{d\tau^2}=R^{\mu}_{.\nu\alpha\beta}u^{\nu}u^{\alpha}\xi^{\beta}$, where $u^\mu$ is 4-velocity vector tangent to geodesic and $\xi^\mu$ is geodesic deviation vector, which connects two points corresponding to the same value of the affine parameter $\tau$ on two close geodesics, was studied in multidimensional Tangherlini spacetime with line...
The question about the appearance of time in the semiclassical limit of quantum gravity continues to be discussed in the literature. It is believed that a temporal Schrödinger equation for matter fields on the background of a classical gravitational field must be true. To obtain this equation, the Born – Oppenheimer approximation for gravity is used. However, the origin of time in this...
A successful compactification scenario should explain two, in principle, rather different properties of the multidimensional space-time. First, we need to show why the evolution of three big dimension is different from the evolution of other dimensions. Second, we need to explain why the 3-dimension subspace is almost isotropic one. We present a scenario which address both issures. Starting...
We consider $f(R)$ gravity model with an additional function of the Gauss-Bonnet term.
We analyze the model in slow-roll regime and estimate inflationary parameters using observational
data to restrict parameters including to the function of the Gauss-Bonnet term.
Probably, physics of particles must consist of two parts. Low energy -standard model. High energy > $\ 10^{5}$ GeV - the early Universe.The first step to modernization of Standard model is insertion of quarks with electric charges q=$-\frac{2}{3}$ and q=$\frac {1}{3}$ in its high energy part. During baryon genesis has deternined the quark composition of protons and neutrons.Baryon genesis was...
We use the sizes of dark spots at the EHT images of supermassive black holes M87 and SgrA for inferring their spins, a>0.75 and a=0.65-0.9, respectively. It is supposed that black spots at the EHH images of M87 and SgrA are the lensed images of their event horizon globes. We reconstruct the form of lensed event horizon by using numerical calculations of the photon trajectories in the Kerr...
Nonstationary configurations of a massless spherically symmetric scalar field are considered. We use an approach to the construction of nonstationary gravitating configurations of a scalar field, which makes it possible to reduce the Einstein-scalar field system to a single equation written in invariant quantities. New exact and numerical nonstationary solutions for a massless scalar field are...
We perform canonical analysis of an action in which 2+1-dimensional gravity with negative cosmological constant is coupled to
cylindrically symmetric dust shell. The resulting phase space is finite dimensional having geometry of SO(2,2) group manifold.
Replacing the Poisson brackets by commutators results in the algebra of observables which is a quantum double D(SL(2)_q).
Deformation...
In the last two decades, a number of observed flares in inactive galaxies have been associated with the tidal disruption of stars by strongly gravitating objects located in the centers of galaxies. Tidal disruption events provide us with a new channel for exploring the central compact objects. In this report, we compare tidal forces and some features of tidal disruption in the vicinities of...
We consider a family of 4-dimensional black hole solutions
governed by natural number $q= 1, 2, 3 , \dots$, which appear in the model
with anisotropic fluid and the equations of state: $p_r = -\rho (2q-1)^{-1}$,
$p_t = - p_r$, where $p_r$ and $p_t$ are pressures in radial and transverse
directions, respectively, and $\rho > 0$ is the density. These equations of state obey weak,...
An extension of the action of the General Relativity in a form of Noether symmetrical fourth order polynomial in the Riemann curvature tensor is suggested and discussed as a possible fundamental theory of gravity in 4-dimensional space-time in direct analogy with the standard fundamental theory of the particle physics with the Lagrangian being polynomial in fundamental fields as well. The...
Interest in primordial black holes (PBHs) has strongly increased after the recent LIGO detection of gravitational waves from merging black holes. It is especially interesting that the intrinsic rotational momentum of these black holes is close to zero, which is difficult to explain for astrophysical black holes, but turns out to be quite logical for PBHs. Also, it is interesting that masses of...
Along with the more well-known massive cosmic strings, their massless counterparts can also exist in the universe. Such strings, having no tension, have a linear energy density and therefore can contribute to the gravitational wave background, generating gravitational bursts of various durations. We are investigating two different mechanisms for the generation of these gravitational bursts....
The formation of solitons foam in the early Universe in the model with two real scalar fields and potential having at least one saddle point and a local maximum is considered. The initial fields distribution is obtained by quantum fluctuations simulation in the framework of Starobinsky's inflation. The formation and evolution of domain walls bounded by strings and solitons foam are discussed...
Nowadays dark matter models with thier own dark interaction becoming more popular. They solve a number of problems of cold dark matter model ($\Lambda$CDM). The simplest viable model of self-interacting dark matter (SIDM) is a model with dark Coulomb-like interaction (with dark photon “y” as carrier) and a set of two types of particles: dark electron ($e_y$) and dark proton ($p_y$). In...
In this talk I will present a new method to define a vacuum state for fields in curved spacetimes, which encompasses the adiabatic prescription. New vacuum states can emerge in situations where the adiabatic method is impossible. Its application is immediate. As it is well known, cosmological observations suggest that the structures in the Universe arise from quantum fluctuations of an...
We study the generation of the baryon asymmetry of the universe (BAU) and relic gravitational waves (GWs) in turbulent hypermagnetic fields (HMFs) in the symmetric phase of the early universe before the electroweak phase transition (EWPT). The noise of HMFs is modeled by the analog of the magnetic hydrodynamics turbulence. The evolution of HMFs is driven the analogs the chiral magnetic effect...
We have shown that the mechanism of gravitational baryogenesis leads to a strong instability of the curvature scalar, resulting in its boundless exponential rise. This instability appears because the coupling of the curvature to baryonic current leads to the fourth order differential equation of motion for the curvature scalar, instead of the algebraic one in the conventional General...
Recently, several experiments reported small violations of radioactivity law in alpha- and beta-decay of heavy nuclei [1,2]. Beside standard exponential time dependence of nuclei decay rate, they found additional periodic terms of the order .05% corresponding to annual and daily nucleus life-time oscillations. It supposes that decay parameter variation can be related to temporary ...
The orbital evolution of a binary system consisting of two clusters of primordial black holes is investigated. The formation of such clusters is predicted in some theoretical models. A cluster consists of the most massive central black hole surrounded by smaller black holes. Similarly to single primordial black holes, clusters can form bounded pairs and merge during the orbital evolution. The...
The theory of gravitational lensing on straight segments of a single cosmic string (CS) located perpendicular to the line of sight has been studied recently in detail. However, more realistic models necessarily have to include the inclinations and bends of the string. Besides, the recent analysis of observational data on the search for gravitational-lens candidates shows a large number of...
We study slow roll single field inflationary scenario and the production of non-thermal fermionic dark matter, together with standard model Higgs, during reheating. For the inflationary scenario, we have considered two models of polynomial potential — one is symmetric about the origin and the other one is not. We fix the coefficients of the potential from the current CMB data from...
