Brane-antibrane Configurations Research Articles

Consequences of U dualities for intersecting branes in the Universe

We consider N-charge, intersecting brane–antibrane configurations in M theory which are smeared uniformly in the common transverse space and may describe our universe. We study the consequences of U dualities and find that they imply relations among the scale factors. We find using Einstein's equations that U dualities also imply a relation among the density ρ and the pressure pi for the single charge case. We present an ansatz for ρ and pi for the N-charge case which yields all the U duality relations among the scale factors. We then study configurations with identical charges, and also with net charges vanishing. We find among other things that, independent of the details of the brane–antibrane dynamics, such four charge configurations lead asymptotically to an effective (3+1)-dimensional expanding universe.

On brane–antibrane forces

In this note, we will discuss two aspects of brane–antibrane forces. In one aspect, we generalize the force calculation of D0-0 of Banks and Susskind to Dp-p for 1 ≤ p ≤ 8. In particular, we find that the force is also divergent for p = 1 while for the other cases (p ≥ 2) the forces are in general finite when Z → 0+, where Z = (Y2)/(2π2α')−1 with Y, the brane–antibrane separation. However, the forces are divergent for all cases when Z < 0, signalling the occurrence of open string tachyon condensation in this regime. The other deals with the puzzling static nature of the supergravity brane–antibrane configurations. We will show that the force on a brane probe due to a brane–antibrane background vanishes when the probe is placed at the location of the coincident brane–antibranes, thereby providing a direct evidence for the existence of general static brane–antibrane configuration in the supergravity approximation.

Family of singular solutions in a SUSY bulk-boundary system

A set of classical solutions of a singular type is found in a 5D SUSY bulk-boundary system. The “parallel” configuration, where the whole components of fields or branes are parallel in the iso-space, naturally appears. It has three free parameters related to the scale freedom in the choice of the brane-matter sources and the “free” wave property of the extra component of the bulk-vector field. The solutions describe brane, anti-brane and brane–anti-brane configurations depending on the parameter choice. Some solutions describe the localization behaviour even after the non-compact limit of the extra space. Stableness is assured. Their meaning in the brane world physics is examined in relation to the stableness, localization, non-singular (kink) solution and the bulk Higgs mechanism.

FromD-bar D Pairs to Branes in Motion

We investigate various supersymmetric brane intersections. Motivated by the recent results on supertubes, we investigate general constraints in which parallel brane-antibrane configurations are supersymmetric. Dual descriptions of these configurations involve systems of branes in relative motion. In particular, we find new supersymmetric configurations which are not related to a static brane intersection by a boost. In these new configurations, the intersection point moves at the speed of light. These systems provide interesting time dependent backgrounds for open strings.

Supersymmetric brane–antibrane configurations

We find a class of flat supersymmetric brane–antibrane configurations. They follow from ordinary brane–antibrane systems by turning on a specific worldvolume background electric field, which corresponds to dissolved fundamental strings. We have clarified in detail how they arise and identified their constituent charges as well as the corresponding supergravity solutions. Adopting the matrix theory description, we construct the worldvolume gauge theories and prove the absence of any tachyonic degrees. We also study supersymmetric solitons of the worldvolume theories.

Brane-antibrane systems on Calabi-Yau spaces

We propose a correspondence between brane-antibrane systems and stable triples (E_1,E_2,T), where E_1,E_2 are holomorphic vector bundles and the tachyon T is a map between them. We demonstrate that, under the assumption of holomorphicity, the brane-antibrane field equations reduce to a set of vortex equations, which are equivalent to the mathematical notion of stability of the triple. We discuss some examples and show that the theory of stable triples suggests a new notion of BPS bound states and stability, and curious relations between brane-antibrane configurations and wrapped branes in higher dimensions.

Black diholes

We present and analyze exact solutions of the Einstein-Maxwell and Einstein-Maxwell-Dilaton equations that describe static pairs of oppositely charged extremal black holes, i.e., black diholes. The holes are suspended in equilibrium in an external magnetic field, or held apart by cosmic strings. We comment as well on the relation of these solutions to brane-antibrane configurations in string and M-theory.

Composite diholes and intersecting brane–antibrane configurations in string/M-theory

We construct new configurations of oppositely charged, static black hole pairs (diholes) in four dimensions which are solutions of low energy string/M-theory. The black holes are extremal and have four different charges. We also consider diholes in other theories with an arbitrary number of abelian gauge fields and scalars, where the black holes can be regarded as composite objects. We uplift the four-charge solutions to higher dimensions in order to describe intersecting brane–antibrane systems in string and M-theory. The properties of the strings and membranes stretched in between these branes and antibranes are studied. Several other generic features of these solutions are discussed.