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V. D. Ivashchuk

Publications and source records attributed to V. D. Ivashchuk.

At least 55 records · Page 3Linked to original sources
arXiv2015

On supersymmetric M-brane configurations with R^{1,1}_{*}/Z_2 submanifold

We obtain new examples of partially supersymmetric M-brane solutions defined on products of Ricci-flat manifolds, which contain two-dimensional Lorentzian submanifold R^{1,1}_{*}/Z_2 with one parallel spinor. The examples belong to the following configurations: M2, M5, M2-M5 and M5-M5. Among them a M2 solution with N =1/32 fractional number of preserved supersymmetries is presented. The examples with three M-branes were considered earlier in our paper with A.A. Golubtsova.

hep-th↗
arXiv2014

On new definitions of SI base units. Why is the "atomic" kilogram preferable

We discuss the role of fundamental constants and measurement data for the Planck, Avogadro and Boltzmann constants and the elementary electric charge in connection with the planned transition to new definitions of four base SI units (the kilogram, mole, ampere and kelvin) in terms of fixed values of these constants. It is proposed to choose a new definition of any base SI unit in terms of a particular fundamental physical constant using a number of criteria, or principles, such as succession relative to the current SI, a sufficient stability of the new unit standards, and concordance between physical dimensions of the unit and the corresponding fundamental constant. It is argued that a redefinition of the kilogram and mole by fixing the values of the atomic mass unit and the Avogadro constant satisfies all these criteria and bears some more advantages against the version with fixed Planck constant: a well founded approach to definition of the ampere and the opportunity to preserve the current relationship between definitions of the mole and the kilogram. It is also argued that the kelvin can be redefined independently of the other three units.

physics.ins-det↗
arXiv2014

Black brane solutions governed by fluxbrane polynomials

A family of composite black brane solutions in the model with scalar fields and fields of forms is presented. The metric of any solution is defined on a manifold which contains a product of several Ricci-flat "internal" spaces. The solutions are governed by moduli functions H_s (s = 1, ..., m) obeying non-linear differential equations with certain boundary conditions imposed. These master equations are equivalent to Toda-like equations and depend upon the non-degenerate (m x m) matrix A. It was conjectured earlier that the functions H_s should be polynomials if A is a Cartan matrix for some semisimple finite-dimensional Lie algebra (of rank m). It is shown that the solutions to master equations may be found by using so-called fluxbrane polynomials which can be calculated (in principle) for any semisimple finite-dimensional Lie algebra. Examples of dilatonic charged black hole (0-brane) solutions related to Lie algebras A_1, A_2, C_2 and G_2 are considered.

hep-th↗
arXiv2014

Quantum billiards in multidimensional models with fields of forms

Bianchi type I cosmological model in (n+1)-dimensional gravity with several forms is considered. When the electric non-composite brane ansatz is adopted, the Wheeler-DeWitt (WDW) equation for the model, written in a conformally covariant form, is analyzed. Under certain restrictions, asymptotic solutions to the WDW equation near the singularity are found, which reduce the problem to the so-called quantum billiard on the (n-1)-dimensional Lobachevsky space H^{n-1}. Two examples of quantum billiards are considered: a 2-dimensional quantum billiard for a 4D model with three 2-forms and a 9D quantum billiard for an 11D model with 120 4-forms which mimics SM2-brane sector of D=11 supergravity. For certain solutions, vanishing of the wave function at the singularity is proved.

gr-qc↗
arXiv2014

Quantum billiards in multidimensional models with branes

Gravitational D-dimensional model with l scalar fields and several forms is considered. When cosmological type diagonal metric is chosen, an electromagnetic composite brane ansatz is adopted and certain restrictions on the branes are imposed the conformally covariant Wheeler-DeWitt (WDW) equation for the model is studied. Under certain restrictions asymptotic solutions to WDW equation are found in the limit of the formation of the billiard walls which reduce the problem to the so-called quantum billiard on the (D+ l -2)-dimensional Lobachevsky space. Two examples of quantum billiards are considered. The first one deals with 9-dimensional quantum billiard for D = 11 model with 330 four-forms which mimic space-like M2- and M5-branes of D=11 supergravity. The second one deals with the 9-dimensional quantum billiard for D =10 gravitational model with one scalar field, 210 four-forms and 120 three-forms which mimic space-like D2-, D4-, FS1- and NS5-branes in D = 10 II A supergravity. It is shown that in both examples wave functions vanish in the limit of the formation of the billiard walls (i.e. we get a quantum resolution of the singularity for 11D model) but magnetic branes could not be neglected in calculations of quantum asymptotic solutions while they are irrelevant for classical oscillating behaviour when all 120 electric branes are present.

hep-th↗
arXiv2013

Triple M-brane configurations and preserved supersymmetries

We investigate all standard triple composite M-brane intersections defined on products of Ricci-flat manifolds for preserving supersymmetries in eleven-dimensional N =1 supergravity. The explicit formulae for computing the numbers of preserved supersymmetries are obtained, which generalize the relations for topologically trivial flat factor spaces presented in the classification by Bergshoeff et al. We obtain certain examples of configurations preserving some fractions of supersymmetries, e.g. containing such factor spaces as K3, C^2_{*}/Z_2, a four-dimensional pp-wave manifold and the two-dimensional pseudo-Euclidean manifold R^{1,1}_{*}/Z_2.

hep-th↗
arXiv2012

More M-branes on product of Ricci-flat manifolds

Partially supersymmetric intersecting (non-marginal) composite M-brane solutions defined on the product of Ricci-flat manifolds M_0 x M_1 x ... x M_n in D= 11 supergravity are considered and formulae for fractional numbers of unbroken supersymmetries are derived for the following configurations of branes: M2 - M2, M2 - M5, M5 - M5 and M2 - M2 - M2. Certain examples of partially supersymmetric configurations are presented.

hep-th↗
arXiv2012

Exact solutions in gravity with a sigma model source

We consider a D-dimensional model of gravity with non-linear "scalar fields" as a matter source. The model is defined on the product manifold M, which contains n Einstein factor spaces. General cosmological type solutions to the field equations are obtained when n-1 factor spaces are Ricci-flat, e.g. when one space M_1 of dimension d_1 > 1 has nonzero scalar curvature. The solutions are defined up to solutions to geodesic equations corresponding to a sigma model target space. Several examples of sigma models are presented. A subclass of spherically-symmetric solutions is studied and a restricted version of "no-hair theorem" for black holes is proved. For the case d_1 =2 a subclass of latent soliton solutions is singled out.

gr-qc↗
arXiv2011

Black brane solutions related to non-singular Kac-Moody algebras

A multidimensional gravitational model containing scalar fields and antisymmetric forms is considered. The manifold is chosen in the form M = M_0 x M_1 x ... x M_n, where M_i are Einstein spaces (i > 0). The sigma-model approach and exact solutions with intersecting composite branes (e.g., solutions with harmonic functions and black brane ones) with intersection rules related to non-singular Kac-Moody (KM) algebras (e.g. hyperbolic ones) are considered. Some examples of black brane solutions are presented, e.g., those corresponding to hyperbolic KM algebras: H_2(q,q) (q > 2), HA_2^(1) = A_2^{++} and to the Lorentzian KM algebra P_{10}.

hep-th↗
arXiv2010

On multidimensional analogs of Melvin's solution for classical series of Lie algebras

A multidimensional generalization of Melvin's solution for an arbitrary simple Lie algebra $\cal G$ is presented. The gravitational model contains n 2-forms and $l \geq n$ scalar fields, wheren is the rank of $\cal G$. The solution is governed by a set of n functions obeying n ordinary differential equations with certain boundary conditions. It was conjectured earlier that these functions should be polynomials (the so-called fluxbrane polynomials). A program (in Maple) for calculating of these polynomials for classical series of Lie algebras is suggested (see Appendix). The polynomials corresponding to the Lie algebra D_4 are obtained. It is conjectured that the polynomials for A_n-, B_n- and C_n-series may be obtained from polynomials for D_{n+1}-series by using certain reduction formulas.

gr-qc↗
arXiv2010

On cosmological-type solutions in multi-dimensional model with Gauss-Bonnet term

A (n + 1)-dimensional Einstein-Gauss-Bonnet (EGB) model is considered. For diagonal cosmological-type metrics, the equations of motion are reduced to a set of Lagrange equations. The effective Lagrangian contains two "minisuperspace" metrics on R^n. The first one is the well-known 2-metric of pseudo-Euclidean signature and the second one is the Finslerian 4-metric that is proportional to n-dimensional Berwald-Moor 4-metric. When a "synchronous-like" time gauge is considered the equations of motion are reduced to an autonomous system of first-order differential equations. For the case of the "pure" Gauss-Bonnet model, two exact solutions with power-law and exponential dependence of scale factors (with respect to "synchronous-like" variable) are obtained. (In the cosmological case the power-law solution was considered earlier in papers of N. Deruelle, A. Toporensky, P. Tretyakov and S. Pavluchenko.) A generalization of the effective Lagrangian to the Lowelock case is conjectured. This hypothesis implies existence of exact solutions with power-law and exponential dependence of scale factors for the "pure" Lowelock model of m-th order.

hep-th↗
arXiv2010

On black holes in multidimensional theory with Ricci-flat internal spaces

A generalization of the Tangherlini solution for the case of n internal Ricci-flat spaces is obtained. It is shown that in the (2+d)-dimensional section a horizon exists only in the trivial case when the internal-space factors are constant. The p-adic analog of the solution is also considered.

gr-qc↗
arXiv2010

Spherically-symmetric solutions with a chain of n internal Ricci-flat spaces

The Schwarzschild solution is generalized for the case of n internal Ricci-flat spaces. It is shown that in the four-dimensional section of the metric a horizon exists only when the internal space scale factors are constant. The scalar-vacuum generalization of the solution is also presented. [This paper is the English translation of the part of Chapter. 2.4 of the author's PhD dissertation (Moscow, 1989).]

gr-qc↗
arXiv2010

On anisotropic Gauss-Bonnet cosmologies in (n+1) dimensions, governed by an n-dimensional Finslerian 4-metric

The (n +1)-dimensional Einstein-Gauss-Bonnet (EGB) model is considered. For diagonal cosmological metrics, the equations of motion are written as a set of Lagrange equations with the effective Lagrangian containing two "minisuperspace" metrics on R^n: a 2-metric of pseudo-Euclidean signature and a Finslerian 4-metric proportional to the n-dimensional Berwald-Moor 4-metric. For the case of the "pure" Gauss-Bonnet model, two exact solutions are presented, those with power-law and exponential dependences of the scale factors (w.r.t. the synchronous time variable). (The power-law solution was considered earlier by N. Deruelle, A. Toporensky, P. Tretyakov, and S. Pavluchenko.) In the case of EGB cosmology, it is shown that for any non-trivial solution with an exponential dependence of scale factors, a_i(τ) = A_i exp(v^i τ), there are no more than three different numbers among v^1, ..., v^n.

gr-qc↗
arXiv2010

On analogues of black brane solutions in the model with multicomponent anisotropic fluid

A family of spherically symmetric solutions with horizon in the model with m-component anisotropic fluid is presented. The metrics are defined on a manifold that contains a product of n-1 Ricci-flat "internal" spaces. The equation of state for any s-th component is defined by a vector U^s belonging to R^{n + 1}. The solutions are governed by moduli functions H_s obeying non-linear differential equations with certain boundary conditions imposed. A simulation of black brane solutions in the model with antisymmetric forms is considered. An example of solution imitating M_2-M_5 configuration (in D =11 supergravity) corresponding to Lie algebra A_2 is presented.

gr-qc↗