The d-dimensional string generated gravity models lead to Einstein-Maxwell equations with quadratic order correction term called the Gauss-Bonnet term. We calculate the quasinormal modes for the d-dimensional charged black hole in the framework of this model. The quasinormal spectrum essentially depends upon the Gauss-Bonnet coupling parameter α which is related to the string scale, and is tota...

We study p = −1 D-brane in type IIB superstring theory. In addition to D-instanton, we obtain the D-wormhole solution in the Einstein frame. This corresponds to the ten-dimensional singular wormhole solution with infinite euclidean action.

The well-known self-similar solution for the two-point correlation function of the density field is valid only in an Einstein – de Sitter universe. We attempt to extend the solution for non – Einstein – de Sitter universes. For this purpose we introduce an idea of quasi-self-similar evolution; this approach is based on the assumption that the evolution of the two-point correlation is a successi...

As is well known, in order for the Einstein–Hilbert action to have a well defined variation, and therefore to be used for deriving field equation through the stationary action principle, it has to be amended by the addition of a suitable boundary term. It has recently been claimed that, if one constructs an action by adding this term to the matter action, the Einstein field equations can be der...

The d-dimensional string generated gravity models lead to Einstein-Maxwell equations with quadratic order correction term called the Gauss-Bonnet term. We calculate the quasinormal modes for the d-dimensional charged black hole in the framework of this model. The quasinormal spectrum essentially depends upon the Gauss-Bonnet coupling parameter α which is related to the string scale, and is tota...

The d-dimensional string generated gravity models lead to Einstein-Maxwell equations with quadratic order correction term called the Gauss-Bonnet term. We calculate the quasinormal modes for the d-dimensional charged black hole in the framework of this model. The quasinormal spectrum essentially depends upon the Gauss-Bonnet coupling parameter α which is related to the string scale, and is tota...

We discuss general properties of the conservation law associated with a local symmetry. Using Noether's theorem and a generalized Belinfante symmetrization procedure in 3+1 dimensions, a symmetric energy-momentum (pseudo) tensor for the gravitational Einstein-Hilbert action is derived and discussed in detail. In 2+1 dimensions, expressions are obtained for energy and angular momentum arising in...

We define an elliptic equation for Hermitian metrics which is related to the Einstein condition. Solutions to this equation are closely related to Kähler-Einstein metrics, and are automatically Kähler-Einstein when a certain non-positive condition is satisfied by c1(M). Given this, a natural flow equation arises taking Hermitian metrics to Kähler metrics. We prove short time existence and regul...

N(k)-quasi Einstein manifolds are introduced and studied.

We define an elliptic equation for Hermitian metrics which is related to the Einstein condition. Solutions to this equation are closely related to Kähler-Einstein metrics, and are automatically Kähler-Einstein when a certain non-positive condition is satisfied by c1(M). Given this, a natural flow equation arises taking Hermitian metrics to Kähler metrics. We prove short time existence and regul...