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21
Sequestering in string theory
 JHEP 0710 (2007) 013 [arXiv:hepth/0703105
"... We study sequestering, a prerequisite for flavorblind supersymmetry breaking in several highscale mediation mechanisms, in compactifications of type IIB string theory. We find that although sequestering is typically absent in unwarped backgrounds, strongly warped compactifications do readily seque ..."
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Cited by 15 (4 self)
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We study sequestering, a prerequisite for flavorblind supersymmetry breaking in several highscale mediation mechanisms, in compactifications of type IIB string theory. We find that although sequestering is typically absent in unwarped backgrounds, strongly warped compactifications do readily sequester. The AdS/CFT dual description in terms of conformal sequestering plays an important role in our analysis, and we establish how sequestering works both on the gravity side and on the gauge theory side. We pay special attention to subtle compactification effects that can disrupt sequestering. Our result is a step toward realizing an appealing pattern of soft terms in a KKLT compactification.
Scalar geometry and masses in CalabiYau string models
 JHEP
"... Abstract We study the geometry of the scalar manifolds emerging in the noscale sector of Kähler moduli and matter fields in generic CalabiYau string compactifications, and describe its implications on scalar masses. We consider both heterotic and orientifold models and compare their characteristi ..."
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Cited by 4 (0 self)
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Abstract We study the geometry of the scalar manifolds emerging in the noscale sector of Kähler moduli and matter fields in generic CalabiYau string compactifications, and describe its implications on scalar masses. We consider both heterotic and orientifold models and compare their characteristics. We start from a general formula for the Kähler potential as a function of the topological compactification data and study the structure of the curvature tensor. We then determine the conditions for the space to be symmetric and show that whenever this is the case the heterotic and the orientifold models give the same scalar manifold. We finally study the structure of scalar masses in this type of geometries, assuming that a generic superpotential triggers spontaneous supersymmetry breaking. We show in particular that their behavior crucially depends on the parameters controlling the departure of the geometry from the coset situation. We first investigate the average sGoldstino mass in the hidden sector and its sign, and study the implications on vacuum metastability and the mass of the lightest scalar. We next examine the soft scalar masses in the visible sector and their flavor structure, and study the possibility of realizing a mild form of sequestering relying on a global symmetry.
Mildly sequestered supergravity models and their realization in string theory
 Nucl. Phys. B
"... Abstract We elaborate on the idea that fivedimensional models where sequestering is spoiled due to contact interactions induced by vector multiplets may still be mildly sequestered if a global version of the gauge symmetry associated to the latter survives in the hidden sector. Interestingly, it h ..."
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Abstract We elaborate on the idea that fivedimensional models where sequestering is spoiled due to contact interactions induced by vector multiplets may still be mildly sequestered if a global version of the gauge symmetry associated to the latter survives in the hidden sector. Interestingly, it has been argued that although in such a situation nontrivial currentcurrent contact interactions are induced by the heavy vector modes, these do not induce soft scalar masses, as a consequence of the global symmetry. We perform a detailed study of how this hybrid mechanism can be implemented in supergravity and string models, focusing on the prototypical case of heterotic Mtheory orbifolds. We emphasize that in general the mechanism works only up to subleading effects suppressed by the ratio between the global symmetry breaking scale in the hidden sector and the vector mass scale or the Planck scale. We also argue that this mild sequestering mechanism allows to rehabilitate the scenario of dilaton domination of supersymmetry breaking, which is incompatible with dilaton stabilization in its original version, by exploiting the fact that hidden brane fields do contribute to the cosmological constant but not to soft terms, thanks to the global symmetry.
The Goldstini Variations
"... Abstract: We study the ‘goldstini ’ scenario of Cheung, Nomura, and Thaler, in which multiple independent supersymmetry (SUSY) breaking sectors lead to multiple wouldbe goldstinos, changing collider and cosmological phenomenology. In supergravity, potentially large corrections to the previous 2m3/ ..."
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Abstract: We study the ‘goldstini ’ scenario of Cheung, Nomura, and Thaler, in which multiple independent supersymmetry (SUSY) breaking sectors lead to multiple wouldbe goldstinos, changing collider and cosmological phenomenology. In supergravity, potentially large corrections to the previous 2m3/2 prediction for goldstini masses can arise when their scalar partners are stabilized far from the origin. Considerations arising from the complexity of realistic string compactifications indicate that many of the independent SUSYbreaking sectors should be conformally sequestered or situated in warped RandallSundrumlike throats, further changing the predicted goldstini masses. If the sequestered hidden sector is a metastable SUSYbreaking sector of the IntriligatorSeibergShih (ISS) type then multiple goldstini can originate from within a single sector, along with many supplementary ‘modulini’, all with masses of order 2m3/2. These fields can couple to the Supersymmetric Standard Model (SSM) via the ‘Goldstino Portal’. Collider signatures involving SSM sparticle decays can provide strong evidence for warpedorconformallysequestered sectors, and of the ISS mechanism of SUSY breaking. Along with axions and photini, the Goldstino Portal gives another potential window to the hidden sectors of string theory.
Thermal Evolution of the Non Supersymmetric Metastable Vacua in
, 811
"... It has been shown that four dimensional N = 2 gauge theories, softly broken to N = 1 by a superpotential term, can accommodate metastable nonsupersymmetric vacua in their moduli space. We study the SU(2) theory at high temperatures in order to determine whether a cooling universe settles in the meta ..."
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It has been shown that four dimensional N = 2 gauge theories, softly broken to N = 1 by a superpotential term, can accommodate metastable nonsupersymmetric vacua in their moduli space. We study the SU(2) theory at high temperatures in order to determine whether a cooling universe settles in the metastable vacuum at zero temperature. We show that the corrections to the free energy because of the BPS dyons are such that may destroy the existence of the metastable vacuum at high temperatures. Nevertheless we demonstrate the universe can settle in the metastable vacuum, provided that the following two conditions are hold: first the superpotential term is not arbitrarily small in comparison to the strong coupling scale of the gauge theory, and second the metastable vacuum lies in the strongly coupled region of the moduli space. 1 1
External Referees: Prof. Marialuisa Frau
"... Riassunto della tesi L’accensione del Large Hadron Collider pone nuove sfide sulla presenza di nuova fisica oltre il Modello Standard. Tra la pletora di modelli costruiti per spiegare i suoi risultati sperimentali, la supersimmetria e ̀ considerata la miglior candidata tra tutta la nuova fisica che ..."
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Riassunto della tesi L’accensione del Large Hadron Collider pone nuove sfide sulla presenza di nuova fisica oltre il Modello Standard. Tra la pletora di modelli costruiti per spiegare i suoi risultati sperimentali, la supersimmetria e ̀ considerata la miglior candidata tra tutta la nuova fisica che si potrebbe scoprire. La supersimmetria risolve la soluzione al problema della gerarchia, porta all’unificazione delle costanti di accoppiamento e contiene candidati per la materia oscura. La miglior candidata per una teoria consistente di gravita ̀ quantistica e ̀ la teoria di stringa. Le teorie di campo supersimmetriche e la teoria delle stringhe sono intimamente connesse. I gradi di liberta ̀ principali nella teoria delle stringhe sono stringhe vibranti i cui estremi sono vincolati ad oggetti estesi detti brane. La teoria di bassa energia con supporto su un insieme di brane coincidenti e ̀ una teoria supersimmetrica di YangMills. Quindi e ̀ molto importante studiare il comportamento delle teorie di gauge supersimmetriche per capire di piu ̀ sulla teoria delle stringhe. Una completa comprensione del limite di bassa energia delle teorie di gauge non e ̀ semplice, perche ́ le teorie quantistiche di campo sono spesso fortemente accoppiate nel loro limite infrarosso. Tuttavia, la supersimmetria ci permette di conoscere molto sulle teorie efficaci di bassa energia.
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"... Abstract:We build explicit supersymmetric unification models where grand unified gauge symmetry breaking and supersymmetry (SUSY) breaking are caused by the same sector. Besides, the SMcharged particles are also predicted by the symmetry breaking sector, and they give the soft SUSY breaking terms t ..."
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Abstract:We build explicit supersymmetric unification models where grand unified gauge symmetry breaking and supersymmetry (SUSY) breaking are caused by the same sector. Besides, the SMcharged particles are also predicted by the symmetry breaking sector, and they give the soft SUSY breaking terms through the socalled gauge mediation. We investigate the mass spectrums in an explicit model with SU(5) and additional gauge groups, and discuss its phenomenological aspects. Especially, nonzero Aterm and Bterm are generated at oneloop level according to the mediation via the vector superfields, so that the electroweak symmetry breaking and 125GeV Higgs mass may be achieved by the large Bterm and Aterm even if the stop mass is around 1TeV.