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128
Ricciflat metrics, harmonic forms and brane resolutions hepth/0012011. 9
"... We discuss the geometry and topology of the complete, noncompact, Ricciflat Stenzel metric, on the tangent bundle of Sn+1. We obtain explicit results for all the metrics, and show how they can be obtained from firstorder equations derivable from a superpotential. We then provide an explicit const ..."
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Cited by 95 (19 self)
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We discuss the geometry and topology of the complete, noncompact, Ricciflat Stenzel metric, on the tangent bundle of Sn+1. We obtain explicit results for all the metrics, and show how they can be obtained from firstorder equations derivable from a superpotential. We then provide an explicit construction for the harmonic selfdual (p,q)forms in the middle dimension p + q = 2(n + 1) for the Stenzel metrics in 2(n + 1) dimensions. Only the (p,p)forms are L2normalisable, while for (p,q)forms the degree of divergence grows with p − q. We also construct a set of Ricciflat metrics whose level surfaces are U(1) bundles over a product of N EinsteinKähler manifolds, and we construct examples of harmonic forms there. As an application, we construct new examples of supersymmetric nonsingular fractional M2branes with such 8dimensional transverse Ricciflat spaces. We show explicitly that the fractional D3branes on the 6dimensional Stenzel metric found by Klebanov and Strassler is supported by a pure (2,1)form, and thus it is supersymmetric, while the example of Pando ZayasTseytlin is supported by a mixture of (1,2) and (2,1) forms. We comment on the implications for the corresponding dual field theories of our resolved brane solutions. Contents 1
Soft Supersymmetry Breaking in Calabiyau Orientifolds with Dbranes . . .
, 2003
"... In this paper we compute the N = 1 effective low energy action for a stack of N spacetime filling D3branes in generic type IIB CalabiYau orientifolds with nontrivial background fluxes by reducing the DiracBornInfeld and ChernSimons actions. Specifically, we determine the Kähler potential for ..."
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Cited by 79 (7 self)
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In this paper we compute the N = 1 effective low energy action for a stack of N spacetime filling D3branes in generic type IIB CalabiYau orientifolds with nontrivial background fluxes by reducing the DiracBornInfeld and ChernSimons actions. Specifically, we determine the Kähler potential for the excitations of the Dbrane including their couplings to all bulk moduli fields. In the effective theory, N = 1 supergravity is spontaneously broken by the presence of fluxes and we compute the induced soft supersymmetry breaking terms. We find an interesting structure in the resulting soft terms with generically universal soft scalar masses.
An open string landscape
 JHEP
, 2005
"... Abstract: The effect of fluxes on open string moduli is studied by analyzing the constraints imposed by supersymmetry on Dbranes in type IIB flux backgrounds. We show that generically the conditions of supersymmetry cannot be maintained when moving along the geometrical moduli space of the brane, s ..."
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Cited by 56 (3 self)
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Abstract: The effect of fluxes on open string moduli is studied by analyzing the constraints imposed by supersymmetry on Dbranes in type IIB flux backgrounds. We show that generically the conditions of supersymmetry cannot be maintained when moving along the geometrical moduli space of the brane, so that open string moduli are lifted. In specific examples, we find that there is a disconnected and discrete set of supersymmetric solutions to the open string equations of motion, which extends the familiar closed string landscape to the open string sector. Permanent addressContents
New string vacua from twistor spaces
 PHYS REV. D
, 2008
"... We find a new family of AdS4 vacua in IIA string theory. The internal space is topologically either the complex projective space CP3 or the “flag manifold” SU(3)/(U(1)×U(1)), but the metric is in general neither Einstein nor Kähler. All known moduli are stabilized by fluxes, without using quantum ef ..."
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Cited by 55 (1 self)
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We find a new family of AdS4 vacua in IIA string theory. The internal space is topologically either the complex projective space CP3 or the “flag manifold” SU(3)/(U(1)×U(1)), but the metric is in general neither Einstein nor Kähler. All known moduli are stabilized by fluxes, without using quantum effects or orientifold planes. The analysis is completely
On the Existence of Metastable Vacua
 in KlebanovStrassler,” JHEP 1009, 087 (2010) [arXiv:0912.3519 [hepth
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Chiral Dbrane models with frozen open string moduli
, 2005
"... Most intersecting Dbrane vacua in the literature contain additional massless adjoint fields in their low energy spectrum. The existence of these additional fields make it difficult to obtain negative beta functions and, eventually, asymptotic freedom. We address this important issue for N = 1 inter ..."
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Cited by 46 (14 self)
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Most intersecting Dbrane vacua in the literature contain additional massless adjoint fields in their low energy spectrum. The existence of these additional fields make it difficult to obtain negative beta functions and, eventually, asymptotic freedom. We address this important issue for N = 1 intersecting Dbrane models, rephrasing the problems in terms of (open string) moduli stabilization. In particular, we consider a Z2 × Z2 orientifold construction where D6branes wrap rigid 3cycles and such extra adjoint fields do not arise. We derive the model building rules and consistency conditions for intersecting branes in this background, and provide N = 1 chiral vacua free of adjoint fields. More precisely, we construct a PatiSalamlike model whose SU(4) gauge group is asymptotically free. We also comment on the application of these results for obtaining gaugino condensation in chiral Dbrane models. Finally, we embed our constructions in the framework of flux compactification, and construct new classes of N = 1 and N = 0 chiral flux vacua.
Generalized nonsupersymmetric flux vacua
, 2008
"... We discuss a novel strategy to construct 4D N = 0 stable flux vacua of type II string theory, based on the existence of BPS bounds for probe Dbranes in some of these backgrounds. In particular, we consider compactifications where Dbranes filling the 4D spacetime obey the same BPS bound as they ..."
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Cited by 45 (11 self)
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We discuss a novel strategy to construct 4D N = 0 stable flux vacua of type II string theory, based on the existence of BPS bounds for probe Dbranes in some of these backgrounds. In particular, we consider compactifications where Dbranes filling the 4D spacetime obey the same BPS bound as they would in an N = 1 compactification, while other Dbranes, like those appearing as domain walls from the 4D perspective, can no longer be BPS. We construct a subfamily of such backgrounds giving rise to 4D N = 0 Minkowski noscale vacua, generalizing the wellknown case of type IIB on a warped CalabiYau. We provide several explicit examples of these constructions, and compute quantities of phenomenological interest like fluxinduced soft terms on Dbranes. Our results have a natural, simple description in the language of Generalized Complex Geometry, and in particular in terms of Dbrane generalized calibrations. Finally, we extend the integrability theorems for 10D supersymmetric type II backgrounds to the N = 0 case and use the results to construct a new class of N = 0 AdS4 compactifications.
The effective action of N = 1 CalabiYau orientifolds
, 2004
"... We determine the N = 1 low energy effective action for compactifications of type IIB string theory on compact CalabiYau orientifolds in the presence of background fluxes from a KaluzaKlein reduction. The analysis is performed for CalabiYau threefolds which admit an isometric and holomorphic invol ..."
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Cited by 39 (6 self)
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We determine the N = 1 low energy effective action for compactifications of type IIB string theory on compact CalabiYau orientifolds in the presence of background fluxes from a KaluzaKlein reduction. The analysis is performed for CalabiYau threefolds which admit an isometric and holomorphic involution. We explicitly compute the Kähler potential, the superpotential and the gauge kinetic functions and check the consistency with N = 1 supergravity. We find a new class of noscale Kähler potentials and show that their structure can be best understood in terms of a dual formulation where some of the chiral multiplets are replaced by linear multiplets. For O3 and O7planes the scalar potential is expressed in terms of a superpotential while for O5 and O9planes also a Dterm and a massive linear multiplet can be present. The relation with the associated Ftheory compactifications is briefly discussed. In recent years it became clear that string theory is not only a theory of fundamental strings but also contains higherdimensional extended objects such as Dbranes and orientifold
Brane resolution through transgression
 Nucl. Phys. B
, 2001
"... Modifications to the singularity structure of D3branes that result from turning on a flux for the RR and NSNS 3forms (fractional D3branes) provide important gravity duals of fourdimensional N = 1 superYangMills theories. We construct generalisations of these modified pbrane solutions in a v ..."
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Cited by 37 (14 self)
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Modifications to the singularity structure of D3branes that result from turning on a flux for the RR and NSNS 3forms (fractional D3branes) provide important gravity duals of fourdimensional N = 1 superYangMills theories. We construct generalisations of these modified pbrane solutions in a variety of other cases, including heterotic 5branes, dyonic strings, M2branes, D2branes, D4branes and type IIA and type IIB strings, by replacing the flat transverse space with a Ricciflat manifold Mn that admits covariantly constant spinors, and turning on a flux built from a harmonic form in Mn, thus deforming the original solution and introducing fractional branes. The construction makes essential use of the ChernSimons or “transgression ” terms in the Bianchiidentity or equation of motion of the field strength that supports the original undeformed solution. If the harmonic form is L2 normalisable, this can result in a deformation of the brane solution that is free of singularities, thus providing viable gravity duals of field theories in diverse dimensions that have less than maximal supersymmetry. We obtain examples of nonsingular heterotic 5branes, dyonic strings, M2branes, type IIA strings, and D2branes.
Warped strings: Selfdual flux and contemporary compactifications
"... String theory is a leading candidate for the quantum theory of gravitation and is the only serious unified theory of all the forces of physics. Additionally, string theory seems to be mathematically unique, and it is possible that all the parameters of physics could be determined by the dynamics of ..."
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Cited by 34 (3 self)
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String theory is a leading candidate for the quantum theory of gravitation and is the only serious unified theory of all the forces of physics. Additionally, string theory seems to be mathematically unique, and it is possible that all the parameters of physics could be determined by the dynamics of string theory. However, there are two intertwined problems. First is that string theory requires ten dimensions for mathematical consistency, so six must be compact or otherwise decoupled from the physics we observe. Also, there exist many different ground states of string theory, so it is difficult to make predictions that are generic to string theory. Therefore, it is crucial to gain a broad understanding of all the string theory vacua, particularly those compactified to four dimensions. In recent years, our understanding of string theory compactifications has expanded greatly to include many new classes of solutions. In this dissertation, I discuss type IIB string compactifications in which the threeform field strengths satisfy a selfduality condition on the internal manifold. I