World-volume Effective Action Research Articles

World-volume effective action of exotic five-brane in M-theory

We study the world-volume effective action of an exotic five-brane, known as the M-theory 5${}^3$-brane (M5${}^3$-brane) in eleven dimensions. The supermultiplet of the world-volume theory is the $\mathcal{N} = (2, 0)$ tensor multiplet in six dimensions. The world-volume action contains three Killing vectors $\hat{k}_{\hat{I}} {}^M \ (\hat{I} =1,2,3)$ associated with the $U(1)^3$ isometry. We find the effective T-duality rule for the eleven-dimensional backgrounds that transforms the M5-brane effective action to that of the M5${}^3$-brane. We also show that our action provides the source term for the M5${}^3$-brane geometry in eleven-dimensional supergravity

Confinement and non‐perturbative tachyons in brane‐antibrane systems

AbstractWe present a worldvolume effective action suitable for the study of the confined phase of a system at weak coupling, and we identify the mechanism by which the fundamental string arises from this action when the Dp and the annihilate. We construct an explicit dual action, appropriate for the strong coupling regime, which realizes a generalized Higgs‐Stückelberg phase for the (relative) (p‐2)‐form dual to the (overall) BI vector, the mechanism put forward by Yi and collaborators for realizing non‐perturbatively the breaking of the overall U(1) gauge group. Our results provide an explicit realization of the perturbative breaking of the overall U(1) in a way that is consistent with the duality symmetries of String Theory.

Confinement and nonperturbative tachyons in brane-antibrane systems

We present a worldvolume effective action suitable for the study of the confined phase of a (Dp,Dp) system at weak coupling. We identify the mechanism by which the fundamental string arises from this action as a confined electric flux string when the Dp and the Dp annihilate. We construct an explicit dual action, more suitable for the study of the strong coupling regime, and show that it realizes a generalized Higgs-Stueckelberg phase for the (relative) (p-2)-form field dual to the (overall) Born-Infeld vector. This is the mechanism put forward by Yi and collaborators based on duality arguments in order to explain the breaking of the overall U(1) gauge group at strong coupling. Indeed, in our dual description the Goldstone boson is a (p-3) form magnetically charged with respect to the overall Born-Infeld vector field. This indicates that the condensing tachyonic objects originate from open D(p-2)-branes stretched between the brane and the antibrane. Our results provide an explicit realization of the breaking of the overall U(1) gauge group perturbatively, in a way consistent with the duality symmetries of string theory.

A microscopical description of Giant gravitons

We construct a non-Abelian world volume effective action for a system of multiple M-theory gravitons. This action contains multipole moment couplings to the eleven-dimensional background potentials. We use these couplings to study, from the microscopical point of view, giant graviton configurations where the gravitons expand into an M2-brane, with the topology of a fuzzy 2-sphere, that lives in the spherical part of the AdS 7× S 4 background or in the AdS part of AdS 4× S 7. When the number of gravitons is large we find perfect agreement with the Abelian, macroscopical, description of giant gravitons given in the literature.

NONCOMMUTATIVE BRANES IN D-BRANE BACKGROUNDS

We study Myers' world volume effective action of coincident D-branes. We investigate a system of N0D0-branes in the geometry of Dp-branes with p = 2 or p = 4. The choice of coordinates can make the action simplified and tractable. For p = 4, we show that a certain pointlike D0-brane configuration solving equations of motion of the action can expand to form a fuzzy two-sphere via magnetic moment effect without changing quantum numbers. We compare noncommutative D0-brane configurations with dual spherical D(6 - p)-brane systems. We also discuss the relation between these configurations and giant gravitons in 11 dimensions.

Strings at the tachyonic vacuum

We study the world-volume effective action of Dp-brane at the tachyonic vacuum which is equivalent to the zero tension limit. Using the Hamiltonian formalism we discuss the algebra of constraints and show that there is a non-trivial ideal of the algebra which corresponds to Virasoro like constraints. The Lagrangian treatment of the model is also considered. For the gauge fixed theory we construct the important subset of classical solutions which is equivalent to the string theory solutions in conformal gauge. We speculate on a possible quantization of the system. At the end a brief discussion of different background fields and fluctuations around the tachyonic vacuum is presented.

S-duality and brane descent relations

We present a description of the type IIB NS-NS p-branes in terms of topological solitons in systems of spacetime-filling brane-antibrane pairs. S-duality implies that these spacetime-filling branes are NS9-branes, S-dual to the D9-branes of the type IIB theory. The possible vortex-like solutions in an NS9,anti-NS9 configuration are identified by looking at its worldvolume effective action. Finally we discuss the implications of these constructions in the description of BPS and non-BPS states in the strongly coupled Heterotic SO(32) theory.

On the effective action of stable non-BPS branes

We study the world-volume effective action of stable non-BPS branes present in Type II theories compactified on K3. In particular, by exploiting the conformal description of these objects available in the orbifold limit, we argue that their world-volume effective theory can be chiral. The resulting anomalies are cancelled through the usual inflow mechanism provided there are anomalous couplings, similar to those of BPS branes, to the twisted R-R fields. We also show that this result is in agreement with the conjectured interpretation of these non-BPS configurations as BPS branes wrapped on non-supersymmetric cycles of the K3.