Browsing by Author "Bertolini, Matteo"

Now showing 1 - 8 of 8
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    Brane world effective actions for D-branes with fluxes
    (2005) Bertolini, Matteo; Billó, Marco; Lerda, Alberto; Morales, Jose F.; Russo, Rodolfo; Physics; Elementary Particle Theory
    We develop systematic string techniques to study brane world effective actions for models with magnetized (or equivalently intersecting) D-branes. In particular, we derive the dependence on all NS-NS moduli of the kinetic terms of the chiral matter in a generic non-supersymmetric brane configurations with non-commuting open string fluxes. Near a N=1 supersymmetric point the effective action is consistent with a Fayet-Iliopoulos supersymmetry breaking and the normalization of the scalar kinetic terms is nothing else than the Kahler metric. We also discuss, from a stringy perspective, D and F term breaking mechanisms, and how, in this generic set up, the Kahler metric enters in the physical Yukawa couplings.
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    Gauge/gravity duality and meta-stable dynamical supersymmetry breaking
    (2006-11-09T11:17:45Z) Argurio, Riccardo; Bertolini, Matteo; Franco, Sebastian; Kachru, Shamit; Physics; Elementary Particle Theory
    We engineer a class of quiver gauge theories with several interesting features by studying D-branes at a simple Calabi-Yau singularity. At weak 't Hooft coupling we argue using field theory techniques that these theories admit both supersymmetric vacua and meta-stable non-supersymmetric vacua, though the arguments indicating the existence of the supersymmetry breaking states are not decisive. At strong 't Hooft coupling we find simple candidate gravity dual descriptions for both sets of vacua.
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    Metastable vacua and D-branes at the conifold
    (2007-03-28T12:34:07Z) Argurio, Riccardo; Bertolini, Matteo; Franco, Sebastian; Kachru, Shamit; Physics; Elementary Particle Theory
    We consider quiver gauge theories arising on D-branes at simple Calabi-Yau singularities (quotients of the conifold). These theories have metastable supersymmetry breaking vacua. The field theoretic mechanism is basically the one exhibited by the examples of Intriligator, Seiberg and Shih in SUSY QCD. In a dual description, the SUSY breaking is captured by the presence of anti-branes. In comparison to our earlier related work, the main improvements of the present construction are that we can reach the free magnetic range of the SUSY QCD theory where the existence of the metastable vacua is on firm footing, and we can see explicitly how the small masses for the quark flavors (necessary to the existence of the SUSY breaking vacua) are dynamically stabilized. One crucial mass term is generated by a stringy instanton. Finally, our models naturally incorporate R-symmetry breaking in the non-supersymmetric vacuum, in a way similar to the examples of Kitano, Ooguri and Ookouchi.
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    New results for AdS/CFT and beyond
    (2005) Bertolini, Matteo; Bigazzi, Francesco; Cotrone, Aldo Lorenzo; Physics; Elementary Particle Theory
    We report on some recent results within the string/gauge theory correspondence, both in the conformal and in the non conformal cases, for a recently found class of N=1 dual pairs. These results provide the first cross check of AdS/CFT and field theory techniques like a-maximization. Moreover, they furnish new examples of cascading gauge theories and the first instance of 4d dynamical supersymmetry breaking embedded in the correspondence
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    On Stable Non-Supersymmetric Vacua at the Bottom of Cascading Theories
    (2006-06-20T09:07:19Z) Argurio, Riccardo; Bertolini, Matteo; Closset, Cyril; Cremonesi, Stefano; Physics; Elementary Particle Theory
    We consider a wide class of cascading gauge theories which usually lead to runaway behaviour in the IR, and discuss possible deformations of the superpotential at the bottom of the cascade which stabilize the runaway direction and provide stable non-supersymmetric vacua. The models we find may allow for a weakly coupled supergravity analysis of dynamical supersymmetric breaking in the context of the gauge/string correspondence.
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    Stringy Instantons at Orbifold Singularities
    (2007-05-15T12:32:10Z) Argurio, Riccardo; Bertolini, Matteo; Ferretti, Gabriele; Lerda, Alberto; Petersson, Christoffer; Physics; Elementary Particle Theory
    We study the effects produced by D-brane instantons on the holomorphic quantities of a D-brane gauge theory at an orbifold singularity. These effects are not limited to reproducing the well known contributions of the gauge theory instantons but also generate extra terms in the superpotential or the prepotential. On these brane instantons there are some neutral fermionic zero-modes in addition to the ones expected from broken supertranslations. They are crucial in correctly reproducing effects which are dual to gauge theory instantons, but they may make some other interesting contributions vanish. We analyze how orientifold projections can remove these zero-modes and thus allow for new superpotential terms. These terms contribute to the dynamics of the effective gauge theory, for instance in the stabilization of runaway directions.
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    Supersymmetry breaking at the end of a cascade of Seiberg dualities
    (2005) Bertolini, Matteo; Bigazzi, Francesco; Cotrone, Aldo Lorenzo; Physics; Elementary Particle Theory
    We study the IR dynamics of the cascading non-conformal quiver theory on N regular and M fractional D3 branes at the tip of the complex cone over the first del Pezzo surface. The horizon of this cone is the irregular Sasaki-Einstein manifold Y 2,1. Our analysis shows that at the end of the cascade supersymmetry is dynamically broken.
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    Unscreening the Gaugino Mass with Chiral Messengers
    (2010-07-23T10:33:51Z) Argurio, Riccardo; Bertolini, Matteo; Ferretti, Gabriele; Mariotti, Alberto; Physics; Elementary Particle Theory
    Gaugino screening, the absence of next-to-leading order corrections to gaugino masses, is a generic feature of gauge mediation models of supersymmetry breaking. We show that in a specific class of models, known as semi-direct gauge mediation, it is possible to avoid gaugino screening by allowing for a chiral messenger sector. Messengers then acquire a mass at some scale, for instance by higgsing or by some auxiliary strong coupling dynamics. We implement this idea in a simple model which we work out explicitly.