arXiv subjects

Sergiu I. Vacaru

Publications and source records attributed to Sergiu I. Vacaru.

At least 145 records · Page 8Linked to original sources

arXiv2003

(Non)Commutative Finsler Geometry from String/M--theory

We synthesize and extend the previous ideas about appearance of both noncommutative and Finsler geometry in string theory with nonvanishing B--field and/or anholonomic (super) frame structures \cite{vstring,vstr2,vnonc,vncf}. There are investigated the limits to the Einstein gravity and string generalizations containing locally anisotropic structures modeled by moving frames. The relation of anholonomic frames and nonlinear connection geometry to M--theory and possible noncommutative versions of locally anisotropic supergravity and D--brane physics is discussed. We construct and analyze new classes of exact solutions with noncommutative local anisotropy describing anholonomically deformed black holes (black ellipsoids) in string gravity, embedded Finsler--string two dimensional structures, solitonically moving black holes in extra dimensions and wormholes with noncommutativity and anisotropy induced from string theory.

hep-th↗

arXiv2002

Anholonomic Triads and New Classes of (2+1)-Dimensional Black Hole solutions

We apply the method of moving anholonomic frames in order to construct new classes of solutions of the Einstein equations on (2+1)-dimensional pseudo-Riemannian spaces. There are investigated black holes with deformed horizons and renormalized locally anisotropic constants. We speculate on properties of such anisotropic black holes with characteristics defined by anholonomic frames and anisotropic interactions of matter and gravity. The thermodynamics of locally anisotropic black holes is discussed in connection with a possible statistical mechanics background based on locally anisotropic variants of Chern-Simons theories.

gr-qc↗

arXiv2002

Anholonomic Frames and Thermodynamic Geometry of 3D Black Holes

We study new classes three dimensional black hole solutions of Einstein equations written in two holonomic and one anholonomic variables with respect to anholonomic frames Thermodynamic properties of such (2+1)-black holes with generic local anisotropy (having elliptitic horizons) are studied by applying geometric methods. The corresponding thermodynamic systems are three dimensional with entropy S being a hypersurface function on mass M, anisotropy angle $θ$ and eccentricity of elliptic deformations $ε>.$ Two-dimensional curved thermodynamic geometries for locally anistropic deformed black holes are constructed after integration on anisotropic parameter $θ$. Two approaches, the first one based on two-dimensional hypersurface parametric geometry and the second one developed in a Ruppeiner-Mrugala-Janyszek fashion, are analyzed. The thermodynamic curvatures are computed and the critical points of curvature vanishing are defined.

gr-qc↗

arXiv2002

Warped Solitonic Deformations and Propagation of Black Holes in 5D Vacuum Gravity

In this paper we use the anholonomic frames method to construct exact solutions for vacuum 5D gravity with metrics having off-diagonal components. The solutions are in general anisotropic and possess interesting features such as an anisotropic warp factor with respect to the extra dimension, or a gravitational scaling/running of some of the physical parameters associated with the solutions. A certain class of solutions are found to describe Schwarzschild black holes which ``solitonically'' propagate in spacetime. The solitonic character of these black hole solutions arises from the embedding of a 3D soliton configuration (e.g. the soliton solutions to the Kadomtsev-Petviashvily or sine-Gordon equations) into certain ansatz functions of the 5D metric. These solitonic solutions may either violate or preserve local Lorentz invariance. In addition there is a connection between these solutions and noncommutative field theory.

hep-th↗

arXiv2002

Nonlinear Connections and Clifford Structures

We present an introduction to the geometry of higher order vector and co--vector bundles (including higher order generalizations of the Finsler geometry and Kaluza--Klein gravity) and review the basic results on Clifford and spinor structures on spaces with generic local anisotropy modeled by higher order nonlinear connections. Geometric applications in locally anisotropic gravity and matter field interactions are considered. This article contains a part of material given by these authors and P. Stavrinos in theirs lectures.

math.DG↗

arXiv2002

Anholonomic Frames, Generalized Killing Equations, and Anisotropic Taub NUT Spinning Spaces

By using anholonomic frames in (pseudo) Riemannian spaces we define anisotropic extensions of Euclidean Taub-NUT spaces. With respect to coordinate frames such spaces are described by off-diagonal metrics which could be diagonalized by corresponding anholonomic transforms. We define the conditions when the 5D vacuum Einstein equations have as solutions anisotropic Taub-NUT spaces. The generalized Killing equations for the configuration space of anisotropically spinning particles (anisotropic spinning space) are analyzed. Simple solutions of the homogeneous part of these equations are expressed in terms of some anisotropically modified Killing-Yano tensors. The general results are applied to the case of the four-dimensional locally anisotropic Taub-NUT manifold with Euclidean signature. We emphasize that all constructions are for(pseudo) Riemannian spaces defined by vacuum soltions, with generic anisotropy, of 5D Einstein equations, the solutions being generated by applying the moving frame method.

hep-th↗

arXiv2002

Ellipsoidal, Cylindrical, Bipolar and Toroidal Wormholes in 5D Gravity

In this paper we construct and analyze new classes of wormhole and flux tube-like solutions for the 5D vacuum Einstein equations. These 5D solutions possess generic local anisotropy which gives rise to a gravitational running or scaling of the Kaluza-Klein ``electric'' and ``magnetic'' charges of these solutions. It is also shown that it is possible to self-consistently construct these anisotropic solutions with various rotational 3D hypersurface geometries (i.e. ellipsoidal, cylindrical, bipolar and toroidal). The local anisotropy of these solutions is handled using the technique of anholonomic frames with their associated nonlinear connection structures [vst]. Through the use of the anholonomic frames the metrics are diagonalized, in contrast to holonomic coordinate frames where the metrics would have off-diagonal components. In the local isotropic limit these solutions are shown to be equivalent to spherically symmetric 5D wormhole and flux tube solutions.

hep-th↗

arXiv2001

Anisotropic Black Holes in Einstein and Brane Gravity

We consider exact solutions of Einstein equations defining static black holes parametrized by off-diagonal metrics which by anholonomic mappings can be equivalently transformed into some diagonal metrics with coefficients being very similar to those from the Schwarzschild and/or Reissner-Nördstrom solutions with anisotropic renormalizations of constants. We emphasize that such classes of solutions, for instance, with ellipsoidal symmetry of horizons, can be constructed even in general relativity theory if off-diagonal metrics and anholonomic frames are introduced into considerations. Such solutions do not violate the Israel's uniqueness theorems on static black hole configurations because at long radial distances one holds the usual Schwarzschild limit. We show that anisotropic deformations of the Reissner-Nördstrom metric can be an exact solution on the brane, re-interpreted as a black hole with an effective electromagnetic like charge anisotropically induced and polarized by higher dimension gravitational interactions.

hep-th↗

arXiv2001

Interactions, Strings and Isotopies in Higher Order Anisotropic Superspaces

The monograph summarizes the author's results on the geometry of anholonomic and locally anisotropic interactions, published in J. Math. Phys., Nucl. Phys. B, Ann. Phys. (NY), JHEP, Rep. Math. Phys., Int. J. Theor. Phys. and in some former Soviet Union and Romanian scientific journals. The main subjects are in the theory of field interactions, strings and diffusion processes on spaces, superspaces and isospaces with higher order anisotropy and inhomogeneity. The approach proceeds by developing the concept of higher order anisotropic (super)space which unifies the logical and manthematical aspects of modern Kaluza--Klein theories and generalized Lagrange and Finsler geometry and leads to modeling of physical processes on higher order fiber (super)bundles provided with nonlinear and distinguished connections and metric structures. This book can be also considered as a pedagogical survey on the mentioned subjects.

math-ph↗

arXiv2001

Ellipsoidal Black Hole - Black Tori Systems in 4D Gravity

We construct new classes of exact solutions of the 4D vacuum Einstein equations which describe ellipsoidal black holes, black tori and combined black hole -- black tori configurations. The solutions can be static or with anisotropic polarizations and running constants. They are defined by off--diagonal metric ansatz which may be diagonalized with respect to anholonomic moving frames. We examine physical properties of such anholonomic gravitational configurations and discuss why the anholonomy may remove the restriction that horizons must be with spherical topology.

hep-th↗

arXiv2001

Warped, Anisotropic Wormhole/Soliton Configurations in Vacuum 5D Gravity

In this paper we apply the anholonomic frames method developed in refs. [1-4] to construct and study anisotropic vacuum field configurations in 5D gravity. Starting with an off--diagonal 5D metric, parameterized in terms of several ansatz functions, we show that using anholonomic frames greatly simplifies the resulting Einstein field equations. These simplified equations contain an interesting freedom in that one can chose one of the ansatz functions and then determine the remaining ansatz functions in terms of this choice. As examples we take one of the ansatz functions to be a solitonic solution of either the Kadomtsev-Petviashvili equation or the sine-Gordon equation. There are several interesting physical consequences of these solutions. First, a certain subclass of the solutions discussed in this paper have an exponential warp factor similar to that of the Randall-Sundrum model. However, the warp factor depends on more than just the 5$^{th}$ coordinate. In addition the warp factor arises from anisotropic vacuum solution rather than from any explicit matter. Second, the solitonic character of these solutions might allow them to be interpreted either as gravitational models for particles (i.e. analogous to the ' t Hooft-Polyakov monopole, but in the context of gravity), or as nonlinear, anisotropic gravitational waves.

hep-th↗

arXiv2001

Black Tori Solutions in Einstein and 5D Gravity

The 'anholonomic frame' method (see gr-qc/0005025, gr-qc/0001060 and hep-th/0110250) is applied for constructing new classes of exact solutions of vacuum Einstein equations with off-diagonal metrics in 4D and 5D gravity. We examine several black tori solutions generated by anholonomic transforms with non-trivial topology of the Schwarzshild metric, which have a static toroidal horizon. We define ansatz and parametrizations which contain warping factors, running constants (in time and extra dimension coordinates) and effective nonlinear gravitational polarizations. Such anisotropic vacuum toroidal metrics, the first example was given in gr-qc/0005025, differ substantially from the well known toroidal black holes (see hep-th/9511188 and gr-qc/9709013) which were constructed as non-vacuum solutions of the Einstein-Maxwell gravity with cosmological constant. Finally, we analyze two anisotropic 5D and 4D black tori solutions with cosmological constant.

hep-th↗

arXiv2001

Off-Diagonal Metrics and Anisotropic Brane Inflation

We study anisotropic reheating (entropy production) on 3D brane from a decaying bulk scalar field in the brane-world picture of the Universe by considering off-diagonal metrics and anholonomic frames. We show that a significant amount of, in general, anisotropic dark radiation is produced in this process unless only the modes which satisfy a specific relation are excited. We conclude that subsequent entropy production within the brane is required in general before primordial nucleosynthesis and that the presence of off-diagonal components (like in the Salam, Strathee and Petracci works) of the bulk metric modifies the processes of entropy production which could substantially change the brane-world picture of the Universe.

hep-th↗

arXiv2001

Locally Anisotropic (2+1)--Dimensional Black Holes

In this paper we analyze the conditions when the Einstein equations with cosmological constant and matter describe (2+1)-dimensional generic locally anisotropic (la) spacetimes of generalized Finsler type. New classes of solutions for such la-spacetimes are constructed. There are investigated black la-holes with the induced from general relativity la-curvature and la-torsion and, as a particular case, the black la-hole solutions are found for teleparallel la-spaces. In a more general context we consider the la-renormalization of black hole constants via the receptivity of la-spacetimes. We speculate on the properties of (2+1)-dimensional black la-holes with unusual characteristics defined by la-interactions of matter and gravity. The thermodynamics of black la-holes is discussed in connection with a possible statistical mechanics background based on locally anisotropic variants of Chern-Simons theories.

gr-qc↗

arXiv2001

A New Method of Constructing Black Hole Solutions in Einstein and 5D Gravity

It is formulated a new 'anholonomic frame' method of constructing exact solutions of Einstein equations with off--diagonal metrics in 4D and 5D gravity. The previous approaches and results are summarized and generalized as three theorems which state the conditions when two types of ansatz result in integrable gravitational field equations. There are constructed and analyzed different classes of anisotropic and/or warped vacuum 5D and 4D metrics describing ellipsoidal black holes with static anisotropic horizons and possible anisotropic gravitational polarizations and/or running constants. We conclude that warped metrics can be defined in 5D vacuum gravity without postulating any brane configurations with specific energy momentum tensors. Finally, the 5D and 4D anisotropic Einstein spaces with cosmological constant are investigated.

hep-th↗

arXiv2001

Off-Diagonal 5D Metrics and Mass Hierarchies with Anisotropies and Running Constants

The gravitational equations of the three dimensional (3D) brane world are investigated for both off-diagonal and warped 5D metrics which can be diagonalized with respect to some anholonomic frames when the gravitational and matter fields dynamics are described by mixed sets of holonomic and anholonomic variables. We construct two new classes of exact solutions of Kaluza-Klein gravity which generalize the Randall-Sundrum metrics to configurations with running on the 5th coordinate gravitational constant and anisotropic dependencies of effective 4D constants on time and/or space variables. We conclude that by introducing gauge fields as off-diagonal components of 5D metrics, or by considering anholonomic frames modelling some anisotropies in extra dimension spacetime, we induce anisotropic tensions (gravitational polarizations) and running of constants on the branes. This way we can generate the TeV scale as a hierarchically suppressed anisotropic mass scale and the Newtonian and general relativistic gravity are reproduced with adequate precisions but with corrections which depend anisotropically on some coordinates.

hep-ph↗

arXiv2001

Dirac Spinor Waves and Solitons in Anisotropic Taub-NUT Spaces

We apply a new general method of anholonomic frames with associated nonlinear connection structure to construct new classes of exact solutions of Einstein-Dirac equations in five dimensional (5D)gravity. Such solutions are parametrized by off-diagonal metrics in coordinate (holonomic) bases, or, equivalently, by diagonal metrics given with respect to some anholonomic frames (pentads, or funfbiends, satisfing corresponding constraint relations). We consider two possibilities of generalization of the Taub NUT metric in order to obtain vacuum solutions of 5D Einsitein equations with effective renormalization of constants having distinguished anisotropies on an angular parameter or on extra dimension coordinate. The constructions are extended to solutions describing self-consistent propagations of 3D Dirac wave packets in 5D anisotropic Taub NUT spacetimes. We show that such anisotropic configurations of spinor matter can induce gravitational 3D solitons being solutions of Kadomtsev-Petviashvili or of sine-Gordon equations.

hep-th↗

arXiv2001

Locally Anisotropic Wormholes and Flux Tubes in 5D Gravity

In this article we examine a class of wormhole and flux tube like solutions to 5D vacuum Einstein equations. These solutions possess generic local anisotropy, and their local isotropic limit is shown to be conformally equivalent to the spherically symmetric 5D solutions of gr-qc/9807086. The anisotropic solutions investigated here have two physically distinct signatures: First, they can give rise to angular-dependent, anisotropic ``electromagnetic'' interactions. Second, they can result in a gravitational running of the ``electric'' and ``magnetic'' charges of the solutions. This gravitational running of the electromagnetic charges is linear rather than logarithmic, and could thus serve as an indirect signal for the presence of higher dimensions. The local anisotropy of these solutions is modeled using the technique of anholonomic frames with respect to which the metrics are diagonalized. If holonomic coordinates frames were used then such metrics would have off-diagonal components.

gr-qc↗