29 research outputs found
Closed String Field Theory with Dynamical D-brane
We consider a closed string field theory with an arbitrary matter current as
a source of the closed string field. We find that the source must satisfy a
constraint equation as a consequence of the BRST invariance of the theory. We
see that it corresponds to the covariant conservation law for the matter
current, and the equation of motion together with this constraint equation
determines the classical behavior of both the closed string field and the
matter. We then consider the boundary state (D-brane) as an example of a
source. We see that the ordinary boundary state cannot be a source of the
closed string field when the string coupling g turns on. By perturbative
expansion, we derive a recursion relation which represents the bulk
backreaction and the D-brane recoil. We also make a comment on the rolling
tachyon boundary state.Comment: 30 pages, LaTeX2e, no figures. Typos are correcte
Thick Brane Worlds and Their Stability
Three types of thick branes, i.e., Poincar\'{e}, de Sitter and Anti-de Sitter
brane are considered. They are realized as the non-singular solutions of the
Einstein equations with the non-trivial dilatons and the potentials. The scalar
perturbations of these systems are also investigated. We find that the
effective potentials of the master equations of the scalar perturbations are
positive definite and consequently these systems are stable under the small
perturbations.Comment: 23 pages, 8figure