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79
Spacetime Instanton Corrections in 4D String Vacua (The Seesaw Mechanism for DBrane Models)
, 2006
"... We systematically investigate instanton corrections from wrapped Euclidean Dbranes to the matter field superpotential of various classes of N=1 supersymmetric Dbrane models in four dimensions. Both gauge invariance and counting fermionic zero modes provide strong constraints on the allowed nonper ..."
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Cited by 139 (28 self)
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We systematically investigate instanton corrections from wrapped Euclidean Dbranes to the matter field superpotential of various classes of N=1 supersymmetric Dbrane models in four dimensions. Both gauge invariance and counting fermionic zero modes provide strong constraints on the allowed nonperturbative superpotential couplings. We outline how the complete instanton computation boils down to the computation of open string disc diagrams for boundary changing operators multiplied by a oneloop vacuum diagram. For concreteness we focus on E2instanton effects in Type IIA vacua with intersecting D6branes, however the same structure emerges for Type IIB and heterotic vacua. The instantons wrapping rigid cycles can potentially destabilise the vacuum or generate perturbatively absent matter couplings such as proton decay operators, µparameter or righthanded neutrino Majorana mass terms. The latter allow the realization of the seesaw mechanism for MSSM like intersecting Dbrane models.
On D3brane potentials in compactifications with fluxes and wrapped Dbranes
 JHEP
, 2006
"... We study the potential governing D3brane motion in a warped throat region of a string compactification with internal fluxes and wrapped Dbranes. If the Kähler moduli of the compact space are stabilized by nonperturbative effects, a D3brane experiences a force due to its interaction with Dbranes ..."
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Cited by 43 (4 self)
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We study the potential governing D3brane motion in a warped throat region of a string compactification with internal fluxes and wrapped Dbranes. If the Kähler moduli of the compact space are stabilized by nonperturbative effects, a D3brane experiences a force due to its interaction with Dbranes wrapping certain fourcycles. We compute this interaction, as a correction to the warped fourcycle volume, using explicit throat backgrounds in supergravity. This amounts to a closedstring channel computation of the loop corrections to the nonperturbative superpotential that stabilizes the volume. We demonstrate for warped conical spaces that the superpotential correction is given by the embedding equation specifying the wrapped fourcycle, in agreement with the general form proposed by Ganor. Our approach automatically provides a solution to the problem of defining a holomorphic gauge coupling on wrapped D7branes in a background with D3branes. Finally, our results have applications to cosmological inflation models in which the inflaton is modeled by a D3brane
Jumping Through Loops: On Soft Terms from Large Volume
 Compactifications, JHEP
"... We subject the phenomenologically successful large volume scenario of hepth/0502058 to a first consistency check in string theory. In particular, we consider whether the expansion of the string effective action is consistent in the presence of Dbranes and Oplanes. Due to the noscale structure at ..."
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Cited by 41 (0 self)
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We subject the phenomenologically successful large volume scenario of hepth/0502058 to a first consistency check in string theory. In particular, we consider whether the expansion of the string effective action is consistent in the presence of Dbranes and Oplanes. Due to the noscale structure at treelevel, the scenario is surprisingly robust. We compute the modification of soft supersymmetry breaking terms, and find only subleading corrections. We also comment that for largevolume limits of toroidal orientifolds and fibered CalabiYau manifolds the corrections can be more important,
Towards an explicit model of dbrane inflation
"... We present a detailed analysis of an explicit model of warped Dbrane inflation, incorporating the effects of moduli stabilization. We consider the potential for D3brane motion in a warped conifold background that includes fluxes and holomorphicallyembedded D7branes involved in moduli stabilizati ..."
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Cited by 35 (3 self)
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We present a detailed analysis of an explicit model of warped Dbrane inflation, incorporating the effects of moduli stabilization. We consider the potential for D3brane motion in a warped conifold background that includes fluxes and holomorphicallyembedded D7branes involved in moduli stabilization. Although the D7branes significantly modify the inflaton potential, they do not correct the quadratic term in the potential, and hence do not cause a uniform change in the slowroll parameter η. Nevertheless, we present a simple example based on the Kuperstein embedding of D7branes, z1 = constant, in which the potential can be finetuned to be sufficiently flat for inflation. To derive this result, it is essential to incorporate the fact that the compactification volume changes slightly as the D3brane moves. We stress that the compactification geometry dictates certain relationships among the parameters in the inflaton Lagrangian, and these microscopic constraints impose severe restrictions on the space of possible models. We note that the shape of the final inflaton potential differs from projections given in earlier studies: in configurations where inflation occurs, it does so near an inflection point. Finally, we comment on the difficulty of making precise cosmological predictions in this scenario. This is the companion paper to [1].
Smeared versus localised sources in flux compactifications
 JHEP
"... We investigate whether vacuum solutions in flux compactifications that are obtained with smeared sources (orientifolds or Dbranes) still survive when the sources are localised. This seems to rely on whether the solutions are BPS or not. First we consider two sets of BPS solutions that both relate t ..."
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Cited by 30 (7 self)
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We investigate whether vacuum solutions in flux compactifications that are obtained with smeared sources (orientifolds or Dbranes) still survive when the sources are localised. This seems to rely on whether the solutions are BPS or not. First we consider two sets of BPS solutions that both relate to the GKP solution through Tdualities: (p+ 1)dimensional solutions from spacetimefilling Opplanes with a conformally Ricciflat internal space, and pdimensional solutions with Opplanes that wrap a 1cycle inside an everywhere negatively curved twisted torus. The relation between the solution with smeared orientifolds and the localised version is worked out in detail. We then demonstrate that a class of nonBPS AdS4 solutions that exist for IASD fluxes and with smeared D3branes (or analogously for ISD fluxes with antiD3branes) does not survive the localisation of the (anti) D3branes. This casts doubts on the stringy consistency of nonBPS solutions that are obtained in the limit of smeared sources. 1 ar
String loop corrections to Kähler potentials
 in orientifolds,” JHEP 0511 (2005) 030 [arXiv:hepth/0508043
"... We determine oneloop string corrections to Kähler potentials in type IIB orientifold compactifications with either N = 1 or N = 2 supersymmetry, including Dbrane ..."
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Cited by 28 (3 self)
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We determine oneloop string corrections to Kähler potentials in type IIB orientifold compactifications with either N = 1 or N = 2 supersymmetry, including Dbrane
Symmetrybreaking vacua and baryon condensates in ads/cft
, 2008
"... We study the gravity duals of symmetrybreaking deformations of superconformal field theories, AdS/CFT dual to Type IIB string theory on AdS5 × Y where Y is a SasakiEinstein manifold. In these vacua both conformal invariance and baryonic symmetries are spontaneously broken. We present a detailed di ..."
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Cited by 26 (8 self)
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We study the gravity duals of symmetrybreaking deformations of superconformal field theories, AdS/CFT dual to Type IIB string theory on AdS5 × Y where Y is a SasakiEinstein manifold. In these vacua both conformal invariance and baryonic symmetries are spontaneously broken. We present a detailed discussion of the supergravity moduli space, which involves flat form fields on asymptotically conical CalabiYau manifolds, and match this to the gauge theory vacuum moduli space. We discuss certain linearised fluctuations of the moduli, identifying the Goldstone bosons associated with spontaneous breaking of nonanomalous baryonic symmetries. The remaining moduli fields are related to spontaneous breaking of anomalous baryonic symmetries. We also elaborate on the proposal that computing condensates of baryon operators is equivalent to computing the partition function of a noncompact Euclidean D3brane in the background supergravity
Micromanaging de Sitter holography
, 2010
"... We develop tools to engineer de Sitter vacua with semiholographic duals, using elliptic fibrations and orientifolds to uplift FreundRubin compactifications with CFT duals. The dual brane construction is compact and constitutes a microscopic realization of the dS/dS correspondence, realizing ddime ..."
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Cited by 24 (7 self)
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We develop tools to engineer de Sitter vacua with semiholographic duals, using elliptic fibrations and orientifolds to uplift FreundRubin compactifications with CFT duals. The dual brane construction is compact and constitutes a microscopic realization of the dS/dS correspondence, realizing ddimensional de Sitter space as a warped compactification down to (d − 1)dimensional de Sitter gravity coupled to a pair of largeN matter sectors. This provides a parametric microscopic interpretation of the GibbonsHawking entropy. We illustrate these ideas with an explicit class of