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Stringy instantons and cascading quivers
 JHEP
"... Dbrane instantons can perturb the quantum field theories on spacetime filling Dbranes by interesting operators. In some cases, these Dbrane instantons are novel “stringy” effects (not interpretable directly as instanton effects in the lowenergy quantum field theory), while in others the Dbrane ..."
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Dbrane instantons can perturb the quantum field theories on spacetime filling Dbranes by interesting operators. In some cases, these Dbrane instantons are novel “stringy” effects (not interpretable directly as instanton effects in the lowenergy quantum field theory), while in others the Dbrane instantons can be directly interpreted as field theory effects. In this note, we describe a situation where both perspectives are available, by studying stringy instantons in quivers which arise at simple CalabiYau singularities. We show that a stringy instanton which wraps an unoccupied node of the quiver, and gives rise to a nonperturbative mass in the spacetime field theory, can be reinterpreted as a conventional gauge theory effect by going up in an appropriate renormalization group cascade. Interestingly, in the cascade, the contribution of the stringy instanton does not come from gauge theory instantons but from strong coupling dynamics. July
WIS/10/07JULDPP hepth/0707.3126 Stringy Instantons and Cascading Quivers
, 2007
"... Dbrane instantons can perturb the quantum field theories on spacetime filling Dbranes by interesting operators. In some cases, these Dbrane instantons are novel “stringy” effects (not interpretable directly as instanton effects in the lowenergy quantum field theory), while in others the Dbrane ..."
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Dbrane instantons can perturb the quantum field theories on spacetime filling Dbranes by interesting operators. In some cases, these Dbrane instantons are novel “stringy” effects (not interpretable directly as instanton effects in the lowenergy quantum field theory), while in others the Dbrane instantons can be directly interpreted as field theory effects. In this note, we describe a situation where both perspectives are available, by studying stringy instantons in quivers which arise at simple CalabiYau singularities. We show that a stringy instanton which wraps an unoccupied node of the quiver, and gives rise to a nonperturbative mass in the spacetime field theory, can be reinterpreted as a conventional gauge theory effect by going up in an appropriate renormalization group cascade. Interestingly, in the cascade, the contribution of the stringy instanton does not come from gauge theory instantons but from strong coupling dynamics.
0805.3361 [hepth] U(1) Mediation of Flux Supersymmetry Breaking
, 2008
"... We study the mediation of supersymmetry breaking triggered by background fluxes in Type II string compactifications with N = 1 supersymmetry. The mediation arises due to an U(1) vector multiplet coupling to both a hidden supersymmetry breaking flux sector and a visible Dbrane sector. The required i ..."
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We study the mediation of supersymmetry breaking triggered by background fluxes in Type II string compactifications with N = 1 supersymmetry. The mediation arises due to an U(1) vector multiplet coupling to both a hidden supersymmetry breaking flux sector and a visible Dbrane sector. The required internal manifolds can be constructed by nonKähler resolutions of singular CalabiYau manifolds. The effective action encoding the U(1) coupling is then determined in terms of the global topological properties of the internal space. We investigate suitable local geometries for the hidden and visible sector in detail. This includes a systematic study of orientifold symmetries of del Pezzo surfaces realized in compact geometries after geometric transition. We construct compact examples admitting the key properties to realize flux supersymmetry breaking and U(1) mediation. Their toric realization allows us to analyze the geometry of curve classes and confirm the topological connection between the hidden and visible sector.