arXiv subjects

Yolanda Lozano

Publications and source records attributed to Yolanda Lozano.

At least 73 records · Page 4Linked to original sources

arXiv2006

The baryon vertex with magnetic flux

In this letter we generalise the baryon vertex configuration of AdS/CFT by adding a suitable instantonic magnetic field on its worldvolume, dissolving D-string charge. A careful analysis of the configuration shows that there is an upper bound on the number of dissolved strings. This should be a manifestation of the stringy exclusion principle. We provide a microscopical description of this configuration in terms of a dielectric effect for the dissolved strings.

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arXiv2006

Type II pp-wave Matrix Models from Point-like Gravitons

The BMN Matrix model can be regarded as a theory of coincident M-theory gravitons, which expand by Myers dielectric effect into the 2-sphere and 5-sphere giant graviton vacua of the theory. In this note we show that, in the same fashion, Matrix String theory in Type IIA pp-wave backgrounds arises from the action for coincident Type IIA gravitons. In Type IIB, we show that the action for coincident gravitons in the maximally supersymmetric pp-wave background gives rise to a Matrix model which supports fuzzy 3-sphere giant graviton vacua with the right behavior in the classical limit. We discuss the relation between our Matrix model and the Tiny Graviton Matrix theory of hep-th/0406214.

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arXiv2005

Fuzzy 5-spheres and pp-wave Matrix Actions

Using the action describing N coincident gravitational waves in M-theory we construct a pp-wave Matrix model cointaning a fuzzy 5-sphere giant graviton solution. This fuzzy 5-sphere is constructed as a U(1) fibration over a fuzzy $CP^2$, and has the correct dependence of the radius with the light-cone momentum, $r^4\sim p^+$, to approach the 5-sphere giant graviton solution of Mc.Greevy et al in the large N limit.

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arXiv2005

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

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.

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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.

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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.

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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.

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arXiv2004

On Non-Abelian Duality

A general study of non-abelian duality is presented. We first identify a possible obstruction to the conformal invariance of the dual theory for non-semisimple groups. We construct the exact non-abelian dual for any Wess-Zumino-Witten (WZW) model for any anomaly free subgroup, and the corresponding extension for coset conformal field theories. We characterize the exact non-abelian dual for $σ$-models with chiral isometries and extend the standard notion of duality to anomalous subgroups of WZW models, thus giving a way of constructing dual transformations for different groups on the left and on the right. We also present some new examples of non-abelian duality for four-dimensional gravitational instantons.

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arXiv2004

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

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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.

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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.

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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.

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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.

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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.

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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.

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arXiv2000

Non-commutative Branes from M-theory

The analysis of the worldvolume effective actions of the M-theory Kaluza-Klein monopole and 9-brane suggests that it should be possible to describe non-abelian configurations of M2-branes or M5-branes if the M2-branes are transverse to the eleventh direction and the M5-branes are wrapped on it. This is determined by the fact that the Kaluza-Klein monopole and the M9-brane are constrained to move in particular isometric spacetimes. We show that the same kind of situation is implied by the analysis of the brane descent relations in M-theory. We compute some of the non-commutative couplings of the worldvolume effective actions of these non-abelian systems of M2 and M5 branes and show that they indicate the existence of configurations corresponding to N branes expanding into a higher dimensional M-brane. The reduction to Type II brings up new descriptions of coincident D-branes at strong coupling. We show that these systems have the right non-commutative charges to describe certain expanded configurations playing a role in the framework of the AdS/CFT correspondence. Finally, we discuss the realization of non-commutative brane configurations as topological solitons in non-abelian brane-antibrane systems.

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arXiv2000

Branes from Unstable Systems of Branes

We discuss various aspects of the description of branes as topological solitons in unstable brane systems of higher dimensions. We first describe a classification of all the possible realisations of branes of M and type II theories as topological solitons of a brane-antibrane system. We then present a description of type IIB NS-NS p-branes in terms of topological solitons in systems of spacetime-filling NS9, anti-NS9 pairs and discuss the implications of these constructions in the description of BPS and non-BPS states in the strongly coupled Heterotic SO(32) theory. We finally present briefly the construction of a conjectured spacetime-filling non-BPS M10-brane, starting point for a brane descent construction of the branes of M-theory.

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arXiv2000

Non-BPS D-brane Solutions in Six Dimensional Orbifolds

Starting with the non-BPS D0-brane solution of IIB/$(-1)^{F_L}I_4$ constructed recently by Eyras and Panda we construct via T-duality the non-BPS D2-brane and D1-brane solutions of IIB/$(-1)^{F_L}I_4$ and IIA/$(-1)^{F_L}I_4$ predicted by Sen. The D2-brane couples magnetically to the vector field of the NS5B-brane living in the twisted sector of the Type IIB orbifold, whereas the D1-brane couples (electrically and magnetically) to the self-dual 2-form potential of the NS5A-brane that is present in the twisted sector of the Type IIA orbifold construction. Finally we discuss the eleven dimensional interpretation of these branes as originating from a non-BPS M1-brane solution of M-theory orientifolded by $Ω_ρI_5$.

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