177,045 research outputs found
Stringy instantons at orbifold singularities
No full textWe 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. © SISSA 2007.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Charting the phase diagram of QCD3
No full textWe study the phase diagram of SU (N) gauge theory in three space-time dimensions with a Chern-Simons term at level k, coupled to two sets of fundamental fermions with masses m1 and m2, respectively. The two-dimensional phase diagram that we propose shows a rich structure and widens in an interesting way previous results in the literature, to which it reduces in some limits. We present several checks of our proposal, including consistency with boson/fermion dualities. In this respect, we extensively comment on the structure of the scalar potential which is needed on the bosonic side of the duality.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
On supersymmetry breaking vacua from D-branes at orientifold singularities
No full textWe present a large class of models of D-branes at (orientifold) Calabi-Yau sin- gularities which enjoy dynamical supersymmetry breaking at low energy, by means of either the SU(5) or 3–2 supersymmetry breaking models. Once embedded in a warped throat or, equivalently, in a large N theory, all models display an instability along a Coulomb branch direction towards supersymmetry preserving vacua. Interestingly, the nature of the run- away mechanism is model-independent and has a precise geometrical interpretation. This naturally suggests the properties a Calabi-Yau singularity should have in order for such instability not to occur.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Metastable supersymmetry breaking and gauge/gravity duality
No full textWe discuss metastable supersymmetry breaking states in gauge theories and in their gravity duals. We then engineer a quiver gauge theory 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 it admits, besides the supersymmetric vacua, also metastable non-supersymmetric vacua, though the arguments indicating the existence of the latter are not decisive. At strong 't Hooft coupling we present a simple candidate gravity dual description for both sets of vacua. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.SCOPUS: cp.jFLWINinfo:eu-repo/semantics/publishe
Natural semidirect gauge mediation and D-branes at singularities
No full textWe consider semidirect gauge mediation models of supersymmetry breaking where the messengers are composite fields and their supersymmetric mass is naturally generated through quartic superpotential couplings. We show that such composite messenger models can be easily embedded in quiver gauge theories arising from D-branes at Calabi-Yau singularities, and argue that semidirect gauge mediation is in fact a very natural option for supersymmetry breaking in D-brane models. We provide several explicit examples and discuss their salient phenomenological properties. © 2009 The American Physical Society.http://arxiv.org/abs/0906.0727SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Gauge/gravity duality and meta-stable dynamical supersymmetry breaking
No full textinfo:eu-repo/semantics/publishe
Gauge/gravity duality and the interplay of various fractional branes
No full textWe consider different types of fractional branes on a Z2 orbifold of the conifold and analyze in detail the corresponding gauge/gravity duality. The gauge theory possesses a rich and varied dynamics, both in the UV and in the IR. We find the dual supergravity solution, which contains both untwisted and twisted 3-form fluxes, related to what are known as deformation and N=2 fractional branes, respectively. We analyze the resulting renormalization group flow from the supergravity perspective, by developing an algorithm to easily extract it. We find hints of a generalization of the familiar cascade of Seiberg dualities due to a nontrivial interplay between the different types of fractional branes. We finally consider the IR behavior in several limits, where the dominant effective dynamics is either confining in a Coulomb phase or runaway, and discuss the resolution of singularities in the dual geometric background. © 2008 The American Physical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Stable non-supersymmetric vacua at the bottom of cascading gauge theories
No full textWe consider a wide class of cascading gauge theories which usually lead to runaway behavior 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 dual weakly coupled supergravity analysis of dynamical supersymmetric breaking. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.SCOPUS: cp.jFLWINinfo:eu-repo/semantics/publishe
Unscreening the gaugino mass with chiral messengers
No full textArXiv ePrint: 1006.5465info:eu-repo/semantics/publishe
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
