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M. Blagojevic

Publications and source records attributed to M. Blagojevic.

At least 19 recordsLinked to original sources
arXiv2013

3D gravity with propagating torsion: Hamiltonian structure of the scalar sector

We study the Hamiltonian structure of the general parity-invariant model of three-dimensional gravity with propagating torsion, with eight parameters in the Lagrangian. In the scalar sector, containing scalar or pseudoscalar modes with respect to maximally symmetric background, the phenomenon of constraint bifurcation is observed and analyzed. The stability of the Hamiltonian structure under linearization is used to identify dynamically acceptable values of parameters.

gr-qc↗
arXiv2007

Supersymmetric 3D gravity with torsion: asymptotic symmetries

We study the structure of asymptotic symmetries in N=1+1 supersymmetric extension of three-dimensional gravity with torsion. Using a natural generalization of the bosonic anti-de Sitter asymptotic conditions, we show that the asymptotic Poisson bracket algebra of the canonical generators has the form of two independent super-Virasoro algebras with different central charges.

gr-qc↗
arXiv2006

Covariant description of the black hole entropy in 3D gravity

We study the entropy of the black hole with torsion using the covariant form of the partition function. The regularization of infinities appearing in the semiclassical calculation is shown to be consistent with the grand canonical boundary conditions. The correct value for the black hole entropy is obtained provided the black hole manifold has two boundaries, one at infinity and one at the horizon. However, one can construct special coordinate systems, in which the entropy is effectively associated with only one of these boundaries.

gr-qc↗
arXiv2006

Black hole entropy in 3D gravity with torsion

The role of torsion in quantum three-dimensional gravity is investigated by studying the partition function of the Euclidean theory in Riemann-Cartan spacetime. The entropy of the black hole with torsion is found to differ from the standard Bekenstein-Hawking result, but its form is in complete agreement with the first law of black hole thermodynamics.

gr-qc↗
arXiv2005

Proceedings to the 8th Workshop 'What Comes Beyond the Standard Models', Bled, July 19. - 29., 2005, Slovenia

Contents: 1. Can MPP Together with Weinberg-Salam Higgs Provide Cosmological Inflation? (D.L. Bennett and H.B. Nielsen) 2. Conserved Charges in 3d Gravity With Torsion (M. Blagojevic and B. Cvetkovic) 3. Mass Matrices of Quarks and Leptons in the Approach Unifying Spins and Charges (A. Borstnik Bracic and N.S. Mankoc Borstnik) 4. Dark Matter From Encapsulated Atoms (C.D. Froggatt and H.B. Nielsen) 5. Dirac Sea for Bosons Also and SUSY for Single Particles (Y. Habara, H.B. Nielsen and M. Ninomiya) 6. Searching for Boundary Conditions in Kaluza-Klein-like Theories (D. Lukman, N.S. Mankoc Borstnik and H. B. Nielsen) 7. Second Quantization of Spinors and Clifford Algebra Objects (N.S. Mankoc Borstnik and H. B. Nielsen) 8. Are there Interesting Problems That Could Increase Understanding of Physics and Mathematics? (R. Mirman) 9. Noncommutative Nonsingular Black Holes (P. Nicolini) 10. Compactified Time and Likely Entropy -- World Inside Time Machine: Closed Time-like Curve (H.B. Nielsen and M. Ninomiya) + Astri Kleppe's Song.

hep-ph↗
arXiv2005

Asymptotic charges in 3d gravity with torsion

We discuss some new developments in three-dimensional gravity with torsion, based on Riemann-Cartan geometry. Using the canonical approach, we study the structure of asymptotic symmetry, clarify its fundamental role in defining the gravitational conserved charges, and explore the influence of the asymptotic structure on the black hole entropy.

gr-qc↗
arXiv2005

On the classical central charge

In the canonical formulation of a classical field theory, symmetry properties are encoded in the Poisson bracket algebra, which may have a central term. Starting from this well understood canonical structure, we derive the related Lagrangian form of the central term.

hep-th↗
arXiv2005

On the theory of the skewon field: From electrodynamics to gravity

The Maxwell equations expressed in terms of the excitation $\H=({\cal H}, {\cal D})$ and the field strength $F=(E,B)$ are metric-free and require an additional constitutive law in order to represent a complete set of field equations. In vacuum, we call this law the ``spacetime relation''. We assume it to be local and linear. Then $\H=\H(F)$ encompasses 36 permittivity/permeability functions characterizing the electromagnetic properties of the vacuum. These 36 functions can be grouped into 20+15+1 functions. Thereof, 20 functions finally yield the dilaton field and the metric of spacetime, 1 function represents the axion field, and 15 functions the (traceless) skewon field $\notS_i{}^j$ (S slash), with $i,j=0,1,2,3$. The hypothesis of the existence of $\notS_i{}^j$ was proposed by three of us in 2002. In this paper we discuss some of the properties of the skewon field, like its electromagnetic energy density, its possible coupling to Einstein-Cartan gravity, and its corresponding gravitational energy.

gr-qc↗
arXiv2004

Canonical structure of 3D gravity with torsion

We study the canonical structure of the topological 3D gravity with torsion, assuming the anti-de Sitter asymptotic conditions. It is shown that the Poisson bracket algebra of the canonical generators has the form of two independent Virasoro algebras with classical central charges. In contrast to the case of general relativity with a cosmological constant, the values of the central charges are different from each other.

gr-qc↗
arXiv2004

Anti-de Sitter 3-dimensional Gravity with Torsion

Using the canonical formalism, we study the asymptotic symmetries of the topological 3-dimensional gravity with torsion. In the anti-de Sitter sector, the symmetries are realized by two independent Virasoro algebras with classical central charges. In the simple case of the teleparallel vacuum geometry, the central charges are equal to each other and have the same value as in general relativity, while in the general Riemann-Cartan geometry, they become different.

gr-qc↗
arXiv2003

3D gravity with torsion as a Chern-Simons gauge theory

We show that topological 3D gravity with torsion can be formulated as a Chern-Simons gauge theory, provided a specific parameter, known as the effective cosmological constant, is negative. In that case, the boundary dynamics of the theory corresponding to anti-de Sitter boundary conditions is described by a conformal field theory with two different central charges.

gr-qc↗
arXiv2003

Asymptotic dynamics in 3D gravity with torsion

We study the nature of boundary dynamics in the teleparallel 3D gravity. The asymptotic field equations with anti-de Sitter boundary conditions yield only two non-trivial boundary modes, related to a conformal field theory with classical central charge. After showing that the teleparallel gravity can be formulated as a Chern-Simons theory, we identify dynamical structure at the boundary as the Liouville theory.

gr-qc↗
arXiv2003

Three lectures on Poincare gauge theory

In these lectures we review the basic structure of Poincare gauge theory of gravity, with emphasis on its fundamental principles and geometric interpretation. A specific limit of this theory, defined by the teleparallel geometry of spacetime, is discussed as a viable alternative for the description of macroscopic gravitational phenomena.

gr-qc↗
arXiv2003

Asymptotic symmetries in 3d gravity with torsion

We study the nature of asymptotic symmetries in topological 3d gravity with torsion. After introducing the concept of asymptotically anti-de Sitter configuration, we find that the canonical realization of the asymptotic symmetry is characterized by the Virasoro algebra with classical central charge, the value of which is the same as in general relativity: c=3l/2G.

gr-qc↗
arXiv2002

Conservation laws in the teleparallel theory with a positive cosmological constant

We study the conservation laws in the teleparallel theory with a positive cosmological constant, an extension of the teleparallel theory possessing solutions with de Sitter asymptotics. Demanding that the canonical generators of the asymptotic symmetry are well defined, we obtain their improved form, which defines the conserved charges of the theory. The physical interpretation of the results is discussed.

gr-qc↗
arXiv2001

Conservation laws in the teleparallel theory of gravity

We study the conservation laws associated with the asymptotic Poincare symmetry of spacetime in the general teleparallel theory of gravity. Demanding that the canonical Poincare generators have well defined functional derivatives in a properly defined phase space, we obtain the improved form of the generators, containing certain surface terms. These terms are shown to represent the values of the related conserved charges: energy-momentum and angular momentum.

hep-th↗