No Arabic abstract
In this paper we consider a model of Poincare gauge theory (PGT) in which a translational gauge field and a Lorentz gauge field are actually identified with the Einsteins gravitational field and a pair of ``Yang-Mills field and its partner, respectively.In this model we re-derive some special solutions and take up one of them. The solution represents a ``Yang-Mills field without its partner field and the Reissner-Nordstrom type spacetime, which are generated by a PGT-gauge charge and its mass.It is main purpose of this paper to investigate the interaction of massless Dirac fields with those fields. As a result, we find an interesting fact that the left-handed massless Dirac fields behave in the different manner from the right-handed ones. This can be explained as to be caused by the direct interaction of Dirac fields with the ``Yang-Mills field. Accordingly, the phenomenon can not happen in the behavior of the neutrino waves in ordinary Reissner-Nordstrom geometry. The difference between left- and right-handed effects is calculated quantitatively, considering the scattering problems of the massless Dirac fields by our Reissner-Nordstrom type black-hole.
The quasinormal modes of a massless Dirac field in the de Rham-Gabadadze-Tolley (dRGT) massive gravity theory with asymptotically de Sitter spacetime are investigated using the Wentzel- Kramers-Brillouin (WKB) approximation. The effective potential for the massless Dirac field due to the dRGT black hole is derived. It is found that the shape of the potential depends crucially on the structure of the graviton mass and the behavior of the quasinormal modes is controlled by the graviton mass parameters. Higher potentials give stronger damping of the quasinormal modes. We compare our results to the Schwarzschild-de Sitter case. Our numerical calculations are checked using Pad$acute{e}$ approximation and found that the quasinormal mode frequencies converge to ones with reasonable accuracy.
Conventional quantum field theory (QFT) is set on flat Minkowski spacetime, where all computable quantities are calculated from the flat metric $eta_{mu u}$. We can redefine the metric of spacetime from the Dirac algebra. In this paper, we study how an quantum electrodynamic interaction can alter the normal gamma matrix to an effective one and result in a shift in the metric perturbatively. We also study how the spin operator is changed under the interaction that contribute to an effective spin operator.
Gravitational collapse of a massless scalar field with the periodic boundary condition in a cubic box is reported. This system can be regarded as a lattice universe model. We construct the initial data for a Gaussian like profile of the scalar field taking the integrability condition associated with the periodic boundary condition into account. For a large initial amplitude, a black hole is formed after a certain period of time. While the scalar field spreads out in the whole region for a small initial amplitude. It is shown that the expansion law in a late time approaches to that of the radiation dominated universe and the matter dominated universe for the small and large initial amplitude cases, respectively. For the large initial amplitude case, the horizon is initially a past outer trapping horizon, whose area decreases with time, and after a certain period of time, it turns to a future outer trapping horizon with the increasing area.
We provide an exact mapping between the Galilian gauge theory, recently advocated by us cite{BMM1, BMM2, BM}, and the Poincare gauge theory. Applying this correspondence we provide a vielbein approach to the geometric formulation of Newtons gravity where no ansatze or additional conditions are required.
In the present work the massless vector field in the de Sitter (dS) space has been quantized. Massless is used here by reference to conformal invariance and propagation on the dS light-cone whereas massive refers to those dS fields which contract at zero curvature unambiguously to massive fields in Minkowski space. Due to the gauge invariance of the massless vector field, its covariant quantization requires an indecomposable representation of the de Sitter group and an indefinite metric quantization. We will work with a specific gauge fixing which leads to the simplest one among all possible related Gupta-Bleuler structures. The field operator will be defined with the help of coordinate independent de Sitter waves (the modes) which are simple to manipulate and most adapted to group theoretical matters. The physical states characterized by the divergencelessness condition will for instance be easy to identify. The whole construction is based on analyticity requirements in the complexified pseudo-Riemanian manifold for the modes and the two-point function.