We examine the effective field equations that are obtained from the axi-dilaton gravity action wi... more We examine the effective field equations that are obtained from the axi-dilaton gravity action with a second order Euler-Poincare term and a cosmological constant in all higher dimensions. We solve these equations for five-dimensional spacetimes possessing homogeneity and isotropy in their three-dimensional subspaces. For a number of interesting special cases we show that the solutions fall into two main classes: The first class consists of time-dependent solutions with spherical or hyperboloidal symmetry which require certain fine-tuning relations between the coupling constants of the model and the cosmological constant. Solutions in the second class are locally static and prove the validity of Birkhoff's staticity theorem in the axi-dilaton gravity. We also give a special class of static solutions, among them the well-known black hole solutions in which the usual electric charge is superseded by an axion charge.
We first reconstruct the conserved (Abbott-Deser) charges in the spin connection formalism of gra... more We first reconstruct the conserved (Abbott-Deser) charges in the spin connection formalism of gravity for asymptotically (Anti)-de Sitter spaces, and then compute the masses of the AdS soliton and the recently found Eguchi-Hanson solitons in generic odd dimensions, unlike the previous result obtained for only five dimensions. These solutions have negative masses compared to the global AdS or AdS/Z_p spacetimes. As a separate note, we also compute the masses of the recent even dimensional Taub-NUT-Reissner-Nordstrom metrics.
We study Dirac equation in Kerr-Taub-NUT spacetime. We use Boyer-Lindquist coordinates and separa... more We study Dirac equation in Kerr-Taub-NUT spacetime. We use Boyer-Lindquist coordinates and separate the resulting equations into radial and angular parts. We get some exact analytical solutions of the angular equations for some special cases. We also obtain the radial wave equations with an effective potential. Finally we discuss the potentials by plotting them as a function of radial distance in a physically acceptable region.
In this work, we perform a detailed analysis of the equatorial motion of the charged test particl... more In this work, we perform a detailed analysis of the equatorial motion of the charged test particles in Kerr-Newman-Taub-NUT spacetime. By working out the orbit equation in the radial direction, we investigate possible orbit types. Concentrating particularly on the circular orbits, we discuss and determine the conditions for the existence of equatorial circular orbits. We study their stability as well. Next, we provide some sample plots of possible orbit configurations and give a detailed discussion of the orbit types.
We obtain a family of pp-wave solutions of Minimal Massive 3d Gravity (MMG) minimally coupled wit... more We obtain a family of pp-wave solutions of Minimal Massive 3d Gravity (MMG) minimally coupled with the Maxwell-Chern-Simons theory. The simultaneous solutions of the MMG and the Maxwell field equations require that the Maxwell field should satisfy an anti-self-duality condition.
In this work, using differential forms, an alternative approach to matter coupling in Minimal Mas... more In this work, using differential forms, an alternative approach to matter coupling in Minimal Massive 3D Gravity (MMG) is presented. In the first part, we consider the minimal coupling of matter Lagrangian assuming that matter Lagrangian 3-form depends on the metric co-frame fields and some matter fields but not on the connections. We construct additional source 2-form to obtain a consistent matter-coupled MMG theory. We see that additional source 2-form involves terms that are quadratic in stress-energy 2-forms. In addition, we derive consistency relation in the language of differential forms. Next, we consider minimal coupling of Dirac Lagrangian where for this case massive spinor-matter Lagrangian depends on both metric co-frames and connection fields. To get a consistent spinor-matter coupled MMG field equation, we obtain additional source 2-form as well. It is shown that with spinor coupling, source 2-form involves terms which are quadratic in covariant derivatives of spinor fi...
In this work, we perform a detailed analysis of the equatorial motion of the charged test particl... more In this work, we perform a detailed analysis of the equatorial motion of the charged test particles in Kerr-Newman-Taub-NUT spacetime. By working out the orbit equation in the radial direction, we examine possible orbit types. We investigate the conditions for existence of bound orbits in causality-preserving region as well as the conditions for existence of circular orbits for charged and uncharged particles. We also study the effect of NUT parameter on Newtonian orbits. Finally, we give exact analytical solutions of equations of equatorial motion for a charged test particle.
We show that gravity cures the infra-red divergence of the Yang monopole when a proper definition... more We show that gravity cures the infra-red divergence of the Yang monopole when a proper definition of conserved quantities in curved backgrounds is used, i.e. the gravitating Yang monopole in cosmological Einstein theory has a finite mass in generic even dimensions (including time). In addition, we find exact Yang-monopole type solutions in the cosmological Einstein-Gauss-Bonnet-Yang-Mills theory and briefly discuss their properties.
In this work, we study the motion of charged test particles in Kerr-Newman-Taub-NUT spacetime. We... more In this work, we study the motion of charged test particles in Kerr-Newman-Taub-NUT spacetime. We analyze the angular and the radial parts of the orbit equations and examine the possible orbit types. We also investigate the spherical orbits and their stabilities. Furthermore, we obtain the analytical solutions of the equations of motion and express them in terms of Jacobian and Weierstrass elliptic functions. Finally, we discuss the observables of the bound motion and calculate the perihelion shift and Lense-Thirring effect for three dimensional bound orbits.
We obtain a family of pp-wave solutions of Minimal Massive 3d Gravity (MMG) minimally coupled wit... more We obtain a family of pp-wave solutions of Minimal Massive 3d Gravity (MMG) minimally coupled with the Maxwell-Chern-Simons theory. The simultaneous solutions of the MMG and the Maxwell field equations require that the Maxwell field should satisfy an anti-self-duality condition. PACS numbers: 04.62.+v, 95.30.Sf E.mail: hcebeci@eskisehir.edu.tr , hcebeci@gmail.com E.mail: tdereli@ku.edu.tr E.mail: secilo@eskisehir.edu.tr
We study models of axi-dilaton gravity in space-time geometries with torsion. We discuss conforma... more We study models of axi-dilaton gravity in space-time geometries with torsion. We discuss conformal rescaling rules in both Riemannian and non-Riemannian formulations. We give static, spherically symmetric solutions and examine their singularity behavior.
ABSTRACT We show that gravity cures the infra-red divergence of the Yang monopole when a proper d... more ABSTRACT We show that gravity cures the infra-red divergence of the Yang monopole when a proper definition of conserved quantities in curved backgrounds is used, i.e. the gravitating Yang monopole in cosmological Einstein theory has a finite mass in generic even dimensions (including time). In addition, we find exact Yang-monopole type solutions in the cosmological Einstein-Gauss-Bonnet-Yang-Mills theory and briefly discuss their properties.
We present an exact solution describing a stationary and axisymmetric object with electromagnetic... more We present an exact solution describing a stationary and axisymmetric object with electromagnetic and dilaton fields. The solution generalizes the usual Kerr-Taub-NUT (Newman-Unti-Tamburino) spacetime in general relativity and is obtained by boosting this spacetime in the fifth dimension and performing a Kaluza-Klein reduction to four dimensions. We also discuss the physical parameters of this solution and calculate its gyromagnetic ratio.
Static, spherically symmetric solutions of axidilaton gravity in D dimensions are given in the Br... more Static, spherically symmetric solutions of axidilaton gravity in D dimensions are given in the Brans-Dicke frame for arbitrary values of the Brans-Dicke constant omega and an axion-dilaton coupling parameter k. The mass and the dilaton and axion charges are determined and a BPS bound is derived. There exists a one-parameter family of black hole solutions in the scale-invariant limit.
ABSTRACT We study Dirac equation in Kerr-Taub-NUT spacetime. We use Boyer-Lindquist coordinates a... more ABSTRACT We study Dirac equation in Kerr-Taub-NUT spacetime. We use Boyer-Lindquist coordinates and separate the resulting equations into radial and angular parts. We get some exact analytical solutions of the angular equations for some special cases. We also obtain the radial wave equations with an effective potential. Finally we discuss the potentials by plotting them as a function of radial distance in a physically acceptable region.
We examine the effective field equations that are obtained from the axi-dilaton gravity action wi... more We examine the effective field equations that are obtained from the axi-dilaton gravity action with a second-order Euler Poincaré term and a cosmological constant in all higher dimensions. We solve these equations for five-dimensional spacetimes possessing homogeneity and isotropy in their three-dimensional subspaces. For a number of interesting special cases, we show that the solutions fall into two main classes:
We examine the effective field equations that are obtained from the axi-dilaton gravity action wi... more We examine the effective field equations that are obtained from the axi-dilaton gravity action with a second order Euler-Poincare term and a cosmological constant in all higher dimensions. We solve these equations for five-dimensional spacetimes possessing homogeneity and isotropy in their three-dimensional subspaces. For a number of interesting special cases we show that the solutions fall into two main classes: The first class consists of time-dependent solutions with spherical or hyperboloidal symmetry which require certain fine-tuning relations between the coupling constants of the model and the cosmological constant. Solutions in the second class are locally static and prove the validity of Birkhoff's staticity theorem in the axi-dilaton gravity. We also give a special class of static solutions, among them the well-known black hole solutions in which the usual electric charge is superseded by an axion charge.
We first reconstruct the conserved (Abbott-Deser) charges in the spin connection formalism of gra... more We first reconstruct the conserved (Abbott-Deser) charges in the spin connection formalism of gravity for asymptotically (Anti)-de Sitter spaces, and then compute the masses of the AdS soliton and the recently found Eguchi-Hanson solitons in generic odd dimensions, unlike the previous result obtained for only five dimensions. These solutions have negative masses compared to the global AdS or AdS/Z_p spacetimes. As a separate note, we also compute the masses of the recent even dimensional Taub-NUT-Reissner-Nordstrom metrics.
We study Dirac equation in Kerr-Taub-NUT spacetime. We use Boyer-Lindquist coordinates and separa... more We study Dirac equation in Kerr-Taub-NUT spacetime. We use Boyer-Lindquist coordinates and separate the resulting equations into radial and angular parts. We get some exact analytical solutions of the angular equations for some special cases. We also obtain the radial wave equations with an effective potential. Finally we discuss the potentials by plotting them as a function of radial distance in a physically acceptable region.
In this work, we perform a detailed analysis of the equatorial motion of the charged test particl... more In this work, we perform a detailed analysis of the equatorial motion of the charged test particles in Kerr-Newman-Taub-NUT spacetime. By working out the orbit equation in the radial direction, we investigate possible orbit types. Concentrating particularly on the circular orbits, we discuss and determine the conditions for the existence of equatorial circular orbits. We study their stability as well. Next, we provide some sample plots of possible orbit configurations and give a detailed discussion of the orbit types.
We obtain a family of pp-wave solutions of Minimal Massive 3d Gravity (MMG) minimally coupled wit... more We obtain a family of pp-wave solutions of Minimal Massive 3d Gravity (MMG) minimally coupled with the Maxwell-Chern-Simons theory. The simultaneous solutions of the MMG and the Maxwell field equations require that the Maxwell field should satisfy an anti-self-duality condition.
In this work, using differential forms, an alternative approach to matter coupling in Minimal Mas... more In this work, using differential forms, an alternative approach to matter coupling in Minimal Massive 3D Gravity (MMG) is presented. In the first part, we consider the minimal coupling of matter Lagrangian assuming that matter Lagrangian 3-form depends on the metric co-frame fields and some matter fields but not on the connections. We construct additional source 2-form to obtain a consistent matter-coupled MMG theory. We see that additional source 2-form involves terms that are quadratic in stress-energy 2-forms. In addition, we derive consistency relation in the language of differential forms. Next, we consider minimal coupling of Dirac Lagrangian where for this case massive spinor-matter Lagrangian depends on both metric co-frames and connection fields. To get a consistent spinor-matter coupled MMG field equation, we obtain additional source 2-form as well. It is shown that with spinor coupling, source 2-form involves terms which are quadratic in covariant derivatives of spinor fi...
In this work, we perform a detailed analysis of the equatorial motion of the charged test particl... more In this work, we perform a detailed analysis of the equatorial motion of the charged test particles in Kerr-Newman-Taub-NUT spacetime. By working out the orbit equation in the radial direction, we examine possible orbit types. We investigate the conditions for existence of bound orbits in causality-preserving region as well as the conditions for existence of circular orbits for charged and uncharged particles. We also study the effect of NUT parameter on Newtonian orbits. Finally, we give exact analytical solutions of equations of equatorial motion for a charged test particle.
We show that gravity cures the infra-red divergence of the Yang monopole when a proper definition... more We show that gravity cures the infra-red divergence of the Yang monopole when a proper definition of conserved quantities in curved backgrounds is used, i.e. the gravitating Yang monopole in cosmological Einstein theory has a finite mass in generic even dimensions (including time). In addition, we find exact Yang-monopole type solutions in the cosmological Einstein-Gauss-Bonnet-Yang-Mills theory and briefly discuss their properties.
In this work, we study the motion of charged test particles in Kerr-Newman-Taub-NUT spacetime. We... more In this work, we study the motion of charged test particles in Kerr-Newman-Taub-NUT spacetime. We analyze the angular and the radial parts of the orbit equations and examine the possible orbit types. We also investigate the spherical orbits and their stabilities. Furthermore, we obtain the analytical solutions of the equations of motion and express them in terms of Jacobian and Weierstrass elliptic functions. Finally, we discuss the observables of the bound motion and calculate the perihelion shift and Lense-Thirring effect for three dimensional bound orbits.
We obtain a family of pp-wave solutions of Minimal Massive 3d Gravity (MMG) minimally coupled wit... more We obtain a family of pp-wave solutions of Minimal Massive 3d Gravity (MMG) minimally coupled with the Maxwell-Chern-Simons theory. The simultaneous solutions of the MMG and the Maxwell field equations require that the Maxwell field should satisfy an anti-self-duality condition. PACS numbers: 04.62.+v, 95.30.Sf E.mail: hcebeci@eskisehir.edu.tr , hcebeci@gmail.com E.mail: tdereli@ku.edu.tr E.mail: secilo@eskisehir.edu.tr
We study models of axi-dilaton gravity in space-time geometries with torsion. We discuss conforma... more We study models of axi-dilaton gravity in space-time geometries with torsion. We discuss conformal rescaling rules in both Riemannian and non-Riemannian formulations. We give static, spherically symmetric solutions and examine their singularity behavior.
ABSTRACT We show that gravity cures the infra-red divergence of the Yang monopole when a proper d... more ABSTRACT We show that gravity cures the infra-red divergence of the Yang monopole when a proper definition of conserved quantities in curved backgrounds is used, i.e. the gravitating Yang monopole in cosmological Einstein theory has a finite mass in generic even dimensions (including time). In addition, we find exact Yang-monopole type solutions in the cosmological Einstein-Gauss-Bonnet-Yang-Mills theory and briefly discuss their properties.
We present an exact solution describing a stationary and axisymmetric object with electromagnetic... more We present an exact solution describing a stationary and axisymmetric object with electromagnetic and dilaton fields. The solution generalizes the usual Kerr-Taub-NUT (Newman-Unti-Tamburino) spacetime in general relativity and is obtained by boosting this spacetime in the fifth dimension and performing a Kaluza-Klein reduction to four dimensions. We also discuss the physical parameters of this solution and calculate its gyromagnetic ratio.
Static, spherically symmetric solutions of axidilaton gravity in D dimensions are given in the Br... more Static, spherically symmetric solutions of axidilaton gravity in D dimensions are given in the Brans-Dicke frame for arbitrary values of the Brans-Dicke constant omega and an axion-dilaton coupling parameter k. The mass and the dilaton and axion charges are determined and a BPS bound is derived. There exists a one-parameter family of black hole solutions in the scale-invariant limit.
ABSTRACT We study Dirac equation in Kerr-Taub-NUT spacetime. We use Boyer-Lindquist coordinates a... more ABSTRACT We study Dirac equation in Kerr-Taub-NUT spacetime. We use Boyer-Lindquist coordinates and separate the resulting equations into radial and angular parts. We get some exact analytical solutions of the angular equations for some special cases. We also obtain the radial wave equations with an effective potential. Finally we discuss the potentials by plotting them as a function of radial distance in a physically acceptable region.
We examine the effective field equations that are obtained from the axi-dilaton gravity action wi... more We examine the effective field equations that are obtained from the axi-dilaton gravity action with a second-order Euler Poincaré term and a cosmological constant in all higher dimensions. We solve these equations for five-dimensional spacetimes possessing homogeneity and isotropy in their three-dimensional subspaces. For a number of interesting special cases, we show that the solutions fall into two main classes:
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