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Bert Janssen

Publications and source records attributed to Bert Janssen.

At least 37 records · Page 2Linked to original sources
arXiv2005

Giant Gravitons in AdS_3 x S^3 x T^4 as Fuzzy Cylinders

Using the non-Abelian action for coincident Type IIB gravitational waves proposed in hep-th/0303183 we show that giant gravitons in the AdS_3 x S^3 x T^4 background can be described in terms of coincident waves expanding into a fuzzy cylinder, spanned by two embedding scalars and one worldvolume scalar. This fuzzy cylinder has dipole and magnetic moments with respect to the 2-form and 6-form potentials of the background, and can be interpreted as a bound state of D1-branes and D5-branes (wrapped on the 4-torus) wrapped around the basis of the cylinder. We show the exact agreement between this description and the Abelian, macroscopical description given in the literature.

hep-th↗
arXiv2005

Giant Gravitons and Fuzzy CP^2

In this article we describe the giant graviton configurations in AdS_m x S^n backgrounds that involve 5-spheres, namely, the giant graviton in AdS_4 x S^7 and the dual giant graviton in AdS_7 x S^4, in terms of dielectric gravitational waves. Thus, we conclude the programme initiated in hep-th/0207199 and pursued in hep-th/0303183 and hep-th/0406148 towards the microscopical description of giant gravitons in AdS_m x S^n spacetimes. In our construction the gravitational waves expand due to Myers dielectric effect onto fuzzy 5-spheres which are described as S^1 bundles over fuzzy CP^2. These fuzzy spheres appear as solutions of the matrix model that comes up as the action for M-theory gravitational waves. The validity of our description is checked by confirming the agreement with the Abelian description in terms of a spherical M5-brane when the number of waves goes to infinity.

hep-th↗
arXiv2004

Giant Gravitons as Fuzzy Manifolds

Giant gravitons are described microscopically in terms of dielectric gravitational waves expanding into fuzzy manifolds. We review these constructions in AdS_m \times S^n spacetimes, discussing the different fuzzy manifolds that appear in each case.

hep-th↗
arXiv2004

The gauge invariance of the non-Abelian Chern-Simons action for D-branes revisited

We present an elegant method to prove the invariance of the Chern-Simons part of the non-Abelian action for N coinciding D-branes under the R-R and NS-NS gauge transformations, by carefully defining what is meant by a background gauge transformation in the non-Abelian world volume action. We study as well the invariance under massive gauge transformations of the massive Type IIA supergravity and show that no massive dielectric couplings are necessary to achieve this invariance. We show that this result is consistent with (massive) T-duality from the non-Abelian action for N D9-branes.

hep-th↗
arXiv2003

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 x S^4 background or in the AdS part of AdS_4 x 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.

hep-th↗
arXiv2003

A Microscopical Description of Giant Gravitons II: The AdS_5 x S^5 Background

In this article we continue with the microscopical investigation of giant graviton configurations in AdS_m x S^n spacetimes, initiated in hep-th/0207199. Using dualities and a Matrix theory derivation we propose an action that describes multiple Type IIB gravitons. This action contains multipole moment couplings to the Type IIB background potentials. Using these couplings, we study, from the microscopical point of view, the giant graviton and dual giant graviton configurations in the AdS_5 x S^5 background. In both cases the gravitons expand into a non-commutative 3-sphere, that is defined as an S^1-bundle over a fuzzy 2-sphere. When the number of gravitons is large we find perfect agreement with the Abelian, macroscopical description of giant gravitons in this spacetime, given in the literature.

hep-th↗
arXiv2003

Probes in fluxbranes and supersymmetry breaking through Hodge-duality

In this letter we consider what happens to an M2-brane probe when Minkowski space is dimensionally reduced to a fluxbrane solution of IIA supergravity. Given that fluxbrane reductions generally break supersymmetry, we look at how supersymmetry is realised on the D2-brane probe after dualisation. We also show how to extend this to more general non-linear sigma models.

hep-th↗
arXiv2002

Non-Abelian Giant Gravitons

We argue that the giant graviton configurations known from the literature have a complementary, microscopical description in terms of multiple gravitational waves undergoing a dielectric (or magnetic moment) effect. We present a non-Abelian effective action for these gravitational waves with dielectric couplings and show that stable dielectric solutions exist. These solutions agree in the large $N$ limit with the giant graviton configurations in the literature.

hep-th↗
arXiv2002

On the Dielectric Effect for Gravitational Waves

We argue that the dielectric effect, mostly studied for systems of coincident D-branes, is also extendible to configurations of multiple gravitational waves. We provide some evidence that Matrix string theory has an alternative interpretation as describing also, in the static gauge, multiple Type IIA gravitational waves. Starting with the linearised action of Matrix string theory in a weakly curved background, we identify the non-Abelian couplings of multiple coinciding gravitons to weak background fields, both in Type IIA and in Type IIB, and we use them to study various dielectric configurations from the point of view of the expanding gravitons. We also identify, in the Abelian limit, some non-perturbative correction terms to the Abelian gravitational wave action.

hep-th↗
arXiv2002

Dielectric Fundamental Strings in Matrix String Theory

Matrix string theory is equivalent to type IIA superstring theory in the light-cone gauge, together with extra degrees of freedom representing D-brane states. It is therefore the appropriate framework in which to study systems of multiple fundamental strings expanding into higher-dimensional D-branes. Starting from Matrix theory in a weakly curved background, we construct the linear couplings of closed string fields to type IIA Matrix strings. As a check, we show that at weak coupling the resulting action reproduces light-cone gauge string theory in a weakly curved background. Further dualities give a type IIB Matrix string theory and a type IIA theory of Matrix strings with winding. We comment on the dielectric effect in each of these theories, giving some explicit solutions describing fundamental strings expanding into various Dp-branes.

hep-th↗
arXiv2002

Chern-Simons Couplings for Dielectric F-Strings in Matrix String Theory

We compute the non-abelian couplings in the Chern-Simons action for a set of coinciding fundamental strings in both the type IIA and type IIB Matrix string theories. Starting from Matrix theory in a weakly curved background, we construct the linear couplings of closed string fields to type IIA Matrix strings. Further dualities give a type IIB Matrix string theory and a type IIA theory of Matrix strings with winding.

hep-th↗
arXiv2001

Massive T-duality in six dimensions

A massive version of T-duality in six dimensions is given, that maps the K3 compactification of Romans' theory onto the K3 compactification of Type IIB theory. This is done by performing a (standard) Kaluza-Klein reduction on six-dimensional massive Type IIA and a Scherk-Schwarz reduction on Type IIB, mapping both theories onto the same five-dimensional theory. We also comment shortly on the difficulties arising if one intends to construct a massive generalisation of the six-dimensional string-string duality.

hep-th↗
arXiv2000

Curved dilatonic brane-worlds and the cosmological constant problem

We construct a model for dilatonic brane worlds with constant curvature on the brane, i.e. a non-zero four-dimensional cosmological constant, given in function of the dilaton coupling and the cosmological constant of the bulk. We compare this family of solutions to other known dilatonic domain wall solutions and apply a self-tunning mechanism to check the stability of our solutions under quantum fluctuations living on the brane.

hep-th↗
arXiv2000

A non-Abelian Chern-Simons term for non-BPS D-branes

We propose a Chern-Simons term for N coinciding non-BPS D-branes. Demanding full U(N) invariance and compatibility with T-duality, it is shown that it is necessary to introduce new interaction terms, through which the non-BPS D-branes couple to all p-form RR fields.

hep-th↗
arXiv2000

Brane World with Bulk Horizons

A brane world in the presence of a bulk black hole is constructed. The brane tension is fine tuned in terms of the black hole mass and cosmological constant. Gravitational perturbations localized on the brane world are discussed.

hep-th↗
arXiv2000

Dilatonic Randall-Sundrum Theory and renormalisation group

We extend Randall-Sundrum dynamics to non-conformal metrics corresponding to non-constant dilaton. We study the appareance of space-time naked singularities and the renormalization group evolution of four-dimensional Newton constant.

hep-th↗
arXiv2000

Curved branes and cosmological (a,b)-models

We construct p-brane solutions with non-trivial world volume metrics and show that applied to supergravity theories, they will lead to threshold BPS bound states of intersecting solutions. However applied to certain specific values of the couplings in cosmological (a,b)-models non-trivial solutions can be constructed.

hep-th↗