We revisit the 4D generalized black hole geometries, obtained by us [1], with a renewed interest, to unfold some aspects of effective gravity in a noncommutative D3-brane formalism. In particular, we argue for the existence of extra dimensions in the gravity decoupling limit in the theory. We show that the theory is rather described by an ordinary geometry and is governed by an effective string...

The transformation of the SL(2, R)/U (1) black hole under a boost of the subgroup U (1) is studied. It is found that the tachyon vertex operators of the black hole go into those of the c = 1 conformal field theory coupled to gravity. The discrete states of the black hole also tend to the discrete states of the 2-d gravity theory. The fate of the extra discrete states of the black hole under boo...

We consider a general, classical theory of gravity in n dimensions, arising from a diffeomorphism invariant Lagrangian. In any such theory, to each vector field, ξ, on spacetime one can associate a local symmetry and, hence, a Noether current (n− 1)-form, j, and (for solutions to the field equations) a Noether charge (n− 2)form, Q, both of which are locally constructed from ξ and the the fields...

String theory is a promising candidate for a fundamental quantum theory of all interactions including Einstein gravity. Some solutions in string theory can be interpreted as black holes. Using the semi-analytic method and WKB method,the quasinormal modes(QNMs)of 1+1 dimensional black hole in string theory are studied.The QNMs of 1+3 dimensional black hole in string theory are also calculated th...

The black hole solutions to Einstein's vacuum field equations are also solutions to the equations of motion of the low energy limit of superstring theory. At the same time, string theory boasts a much broader and richer collection of black hole solutions. Fortunately, string theories also possess a remarkable set of duality symmetries relating states within and between different string theories...

in this paper the dynamic of a droplet on a surface with a hole is investigated under gravitational effect by using lattice boltzmann method. incompressible two-phase flow with high density ratio proposed by lee is considered. cahn’s theory is used to observe the wettability of the surface in contact with liquid and gas phases. several parameters such as contact angle, surface tension and gravi...