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V. I. Tselyaev

Publications and source records attributed to V. I. Tselyaev.

14 recordsLinked to original sources
arXiv2026

Antigravity mechanism in the theory of dual relativity

In the paper, one of the physical consequences of the recently developed theory of dual relativity (TDR) is considered. The general framework of TDR is described and some results previously obtained within this theory are summarized. The total action functional of TDR includes the action functionals of matter fields of two kinds: ordinary and dual. Based on the general equations of the theory, formulas are derived for the effective action functional of a system of point-like massive particles belonging to both kinds of matter, in the Newtonian limit. This functional includes an interaction term, which has the form of the gravitational interaction energy in Newtonian mechanics. It is shown that this energy is positive in the case of interaction between particles of ordinary and dual matter. This result indicates that this interaction has antigravitational nature.

gr-qc↗
arXiv2024

Dual relativity and its cosmological consequences

A new version of the modified theory of gravity is formulated in which two physical metrics are constructed out of two vierbeins connected with each other by the duality condition including the flat metric of the prior geometry. The duality condition plays a crucial role in this theoretical scheme, and thus gives the name to the whole approach: the theory of dual relativity (TDR). The energy-momentum tensor density of a closed system is defined, and the conservation law for this tensor density is deduced. In the TDR it is assumed that there exist two kinds of matter governed by the mutually dual physical metrics, and it is shown that the interaction between them has antigravitational character. A cosmological limit of the field equations of the TDR is considered. In this limit, there are two types of solutions: with positive and with negative energy density. The first type admits the existence of a stable Universe as a whole. The second type gives the oscillations of the cosmological scale factor within the finite limits excluding the zero point, that can be treated as a solution for a certain domain of the Universe. For this type of solutions, the model formula for the dependence of the Hubble parameter $H$ on the redshift $z$ has been obtained. The values of the parameters of this formula are found from the fit to the available $H(z)$ data. It is obtained that the TDR gives a better description of the $H(z)$ data as compared to the flat $Λ$CDM model. The important consequences of the obtained results are, first, their incompatibility with the standard Big Bang model and, second, the existence of two critical values of the scale factor determining the points of its sharp change in the course of oscillations in the solutions of the second type.

gr-qc↗
arXiv2013

Nuclear shell structure and response toward the limits of mass, temperature and isospin

We present a short overview of our recent theoretical developments aiming at the description of exotic nuclear phenomena to be reached and studied at the next-generation radioactive beam facilities. Applications to nuclear shell structure and response of nuclei at the limits of their existence, with a special focus on the physics cases of astrophysical importance, are discussed.

nucl-th↗
arXiv2013

Subtraction method and stability condition in the extended RPA theories

The extended RPA theories are analyzed from the point of view of the problem of stability of their solutions. Three kinds of such theories are considered: the second RPA and two versions of the quasiparticle-phonon coupling model within the time-blocking approximation: the model including 1p1h*phonon configurations and the two-phonon model. It is shown that stability is ensured by making use of the subtraction method proposed previously to solve double counting problem in these theories. This enables one to generalize the famous Thouless theorem proved in the case of the RPA. These results are illustrated by an example of schematic model.

nucl-th↗
arXiv2009

Elimination of $0^+$ spurious states in the quasiparticle time blocking approximation

The quasiparticle time blocking approximation (QTBA) is considered as a model for the description of excitations in open-shell nuclei. The QTBA is an extension of the quasiparticle random phase approximation that includes quasiparticle-phonon coupling. In the present version of the QTBA, the pairing correlations are included within the framework of the BCS approximation. Thus, in this model, the $0^+$ spurious states appear, which are caused by the breaking of the symmetry related to the particle-number conservation. In this work, the method is described which solves the problem of the $0^+$ spurious states in the QTBA with the help of the projection technique. The method is illustrated by calculations of $0^+$ excitations in $^{120}$Sn nucleus.

nucl-th↗
arXiv2008

Self-consistent calculations within the Green's function method including particle-phonon coupling and the single-particle continuum

The Green's function method in the \emph{Quasiparticle Time Blocking Approximation} is applied to nuclear excitations in $^{132}$Sn and $^{208}$Pb. The calculations are performed self-consistently using a Skyrme interaction. The method combines the conventional RPA with an exact single-particle continuum treatment and considers in a consistent way the particle-phonon coupling. We reproduce not only the experimental values of low- and high-lying collective states but we also obtain fair agreement with the data of non-collective low-lying states that are strongly influenced by the particle-phonon coupling.

nucl-th↗
arXiv2007

Majorana spinors and extended Lorentz symmetry in four-dimensional theory

An extended local Lorentz symmetry in four-dimensional (4D) theory is considered. A source of this symmetry is a group of general linear transformations of four-component Majorana spinors GL(4,M) which is isomorphic to GL(4,R) and is the covering of an extended Lorentz group in a 6D Minkowski space M(3,3) including superluminal and scaling transformations. Physical space-time is assumed to be a 4D pseudo-Riemannian manifold. To connect the extended Lorentz symmetry in the M(3,3) space with the physical space-time, a fiber bundle over the 4D manifold is introduced with M(3,3) as a typical fiber. The action is constructed which is invariant with respect to both general 4D coordinate and local GL(4,M) spinor transformations. The components of the metric on the 6D fiber are expressed in terms of the 4D pseudo-Riemannian metric and two extra complex fields: 4D vector and scalar ones. These extra fields describe in the general case massive particles interacting with an extra U(1) gauge field and weakly interacting with ordinary particles, i.e. possessing properties of invisible (dark) matter.

gr-qc↗
arXiv2005

Description of electric dipole excitations in the tin isotopes within the quasiparticle time blocking approximation

The quasiparticle time blocking approximation (QTBA) is applied to describe E1 excitations in the even-even tin isotopes. Within the model pairing correlations, two-quasiparticle (2q), and 2q*phonon configurations are included. Thus the QTBA is an extension of the quasiparticle random phase approximation to include quasiparticle-phonon coupling. Calculational formulas are presented in case of neutral excitations in the spherically symmetric system. The main equations are written in the coordinate representation that allows to take into account single-particle continuum completely. The E1 photoabsorption cross sections have been calculated in nuclei 116,120,124Sn. It has been obtained that the 2q*phonon configurations provide noticeable fragmentation of the giant dipole resonance resulting in appearance of significant spreading width. The results are compared with available experimental data.

nucl-th↗
arXiv2005

Quasiparticle time blocking approximation within the framework of generalized Green function formalism

The problem of the microscopic description of excited states of the even-even open-shell atomic nuclei is considered. A model is formulated which allows one to go beyond the quasiparticle random phase approximation. The physical content of the model is determined by the quasiparticle time blocking approximation (QTBA) which enables one to include contributions of the two-quasiparticle and the two-phonon configurations, while excluding (blocking) more complicated intermediate states. In addition, the QTBA ensures consistent treatment of ground state correlations in the Fermi systems with pairing. The model is based on the generalized Green function formalism (GGFF) in which the normal and the anomalous Green functions are treated in a unified way in terms of the components of generalized Green functions in a doubled space. Modification of the GGFF is considered in the case when the many-body nuclear Hamiltonian contains two-, three-, and other many-particle effective forces.

nucl-th↗
arXiv2004

Density Matrix Functional Theory with account of pairing correlations

The extension of the density functional theory (DFT) to include pairing correlations without formal violation of the particle-number conservation condition is described. This version of the theory can be considered as a foundation of the application of existing DFT plus pairing approaches to atoms, molecules, ultracooled and magnetically trapped atomic Fermi gases, and atomic nuclei where the number of particles is exactly conserved. The connection with the Hartree-Fock-Bogoliubov theory is discussed. The method of the quasilocal reduction of the nonlocal theory is described. This quasilocal reduction allows to obtain equations of motion which are much more simple for the numerical solution than the equations corresponding to the nonlocal case.

nucl-th↗
arXiv2004

Nuclear incompressibility in the quasilocal density functional theory

We explore the ability of the recently established quasilocal density functional theory for describing the isoscalar giant monopole resonance. Within this theory we use the scaling approach and perform constrained calculations for obtaining the cubic and inverse energy weighted moments (sum rules) of the RPA strength. The meaning of the sum rule approach in this case is discussed. Numerical calculations are carried out using Gogny forces and an excellent agreement is found with HF + RPA results previously reported in literature. The nuclear matter compression modulus predicted in our model lies in the range 210-230 MeV which agrees with earlier findings. The information provided by the sum rule approach in the case of nuclei near the neutron drip line is also discussed.

nucl-th↗
arXiv2002

Excitations of the unstable nuclei ^{48}Ni and ^{49}Ni

The isoscalar E1 and E2 resonances in the proton-rich nuclei ^{48,49}Ni and the {f_{7/2}3^-} multiplet in ^{49}Ni have been calculated taking into account the single-particle continuum exactly. The analogous calculations for the mirror nuclei ^{48}Ca and ^{49}Sc are presented. The models used are the continuum RPA for ^{48}Ni, ^{48}Ca and the Odd RPA for ^{49}Ni, ^{49}Sc, the latter has been developed recently and describes both single-particle and collective excitations of an odd nucleus on a common basis. In all four nuclei we obtained a distinct splitting of the isoscalar E1 resonance into 1 h-bar omega and 3 h-bar omega peaks at about 11 MeV and 30 MeV, respectively. The main part of the isoscalar E1 EWSR is exhausted by the 3 h-bar omega resonances. The 1 h-bar omega resonances exhaust about 35% of this EWSR in ^{48,49}Ni and about 22% in ^{48}Ca and ^{49}Sc. All seven {f_{7/2}3^-} multiplet members in ^{49}Ni are calculated to be in the (6-8) MeV energy region and have noticeable escape widths.

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arXiv2002

Quasi-Local Density Functional Theory and its Application within Extended Thomas-Fermi Approximation

A generalization of the Density Functional Theory is proposed. The theory developed leads to single-particle equations of motion with a quasi-local mean-field operator, which contains a quasi-particle position-dependent effective mass and a spin-orbit potential. The energy density functional is constructed using the Extended Thomas-Fermi approximation. Within the framework of this approach the ground-state properties of the doubly magic nuclei are considered. The calculations have been performed using the finite-range Gogny D1S force. The results are compared with the exact Hartree-Fock calculations.

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