Dissertations / Theses on the topic 'Supersymmetry, superspace, supersymmetry breaking'
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SIANI, MASSIMO VINCENZO DUILIO. "Perturbative and non perturbative infrared behaviour of supersymmetric gauge theories." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2011. http://hdl.handle.net/10281/18817.
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Maraventano, Sara. "Superspace formulation of higher-derivative actions from D-branes." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15828/.
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Higher-derivative operators play a fundamental role in the development of effective field theories. This thesis deals with the study of such operators in the context of the effective
low-energy theory of type IIB superstring theory. In particular, we revisit a past attempt to find the supersymmetric form of the higher-derivatives for the D7-brane modulus in an orbifold compactification at the level of a globally supersymmetric theory. These higher-derivatives descend from the Dirac-Born-Infeld action of the D7-brane. Starting from the
component Lagrangian the task is to identify the supersymmetric higher-derivative operator which reproduces the component terms. To this end, we develop a new systematic
approach to determine this supersymmetric form and test it for the present example.
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Sudano, Matthew C. "Topics in supersymmetry and supersymmetry breaking." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3355841.
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Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed July 7, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 95-102).
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Markou, Chrysoula. "Nonlinear supersymmetry, spontaneous supersymmetry breaking and extra dimensions." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS227.
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Le sujet de cette thèse est la brisure partielle de la supersymétrie N=2 en quatres et cinq dimensions de l'espace-temps. Dans le premiere cas, nous étudions hors de la couche de masse la réalisation non-linéaire de la supersymétrie N=1 brisée en utilisant de superchamps N=2 nilpotents qui contiennent les degrés de liberté de Goldstone du multiplet massif de N=1 de spin-3/2. Ces superchamps du Goldstino peuvent être de Maxwell ou de simple-tenseur. La brisure partielle est généré par une combinaison des termes électriques et magnétiques de Fayet-Iliopoulos, dont les coefficients peuvent être considérés comme de paramètres des déformations des transformations de l'algèbre de la supersymétrie brisée, ou, en plus, comme de déformations des superchamps eux-mêmes. D'interactions entre les multiplets du Goldstino deformés avec des multiplets pas deformés donne lieu à un mécanisme de super-Brout-Englert-Higgs mais sans la gravité, en raison duquel un multiplet N=1 vectoriel absorbe un multiplet N=1 linéaire et devient massif. Dans le deuxième cas, nous étudions sur la couche de masse la brisure partielle qui est généré par la valeur moyenne du dilaton qui est linéaire de la dimension supplémentaire et ce dernier est un modèle du dual holographique de little string theory. Un jaugement particulier de la supergravité N=2, D=5 peut incorporer cet modèle, et la supersymétrie N=1 reste intacte en quatres dimensions. Après compactification de la dimension supplémentaire, nous trouvons que l'introduction de branes est compatible avec la direction de la supersymétrie pas briséeThe subject matter of the present thesis is the partial breaking of N=2 supersymmetry in four and in five spacetime dimensions. In the first case, we study the off-shell nonlinear realization of the broken N=1 superymmetry with the use of nilpotent N=2 superfields that contain the Goldstone degrees of freedom of the massive spin-3/2 multiplet of N=1 supersymmetry. These Goldstino superfields can either be the Maxwell or the single-tensor multiplet. The partial breaking is induced by a combination of magnetic and electric Fayet-Iliopoulos terms, the coefficients of which can be seen as deformation parameters of the transformations of the broken supersymmetry algebra or, futhermore, as deformations of the superfields themselves. Interactions of deformed Goldstino multiplets with undeformed multiplets generate a super-Brout-Englert-Higgs effect but without gravity, in which an N=1 vector multiplet absorbs an N=1 linear multiplet and becomes massive. In the second case, we study on-shell the partial breaking that is induced by the background value of the dilaton that is linear in the extra dimension, with the latter being a toy model of the holographic dual of little string theory. A particular gauging of N=2, D=5 supergravity can accommodate this model, with N=1 supersymmetry remaining intact in four dimensions. Upon compactification of the extra dimension, we find that the introduction of branes is compatible with the direction of the unbroken supersymmetry
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Dolan, M. J. "Phenomenology of supersymmetry breaking." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598584.
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In the introductory chapter 1 review the hierarchy problem and some other unresolved issues in the Standard Model, and introduce the Minimal Supersymmetric Standard Model as a possible resolution of these issues. I review different mechanisms of supersymmetry breaking and examples from each class. I discuss the effects of superparticles on indirect Standard Model observables which will be used in the thesis, illustrating in particular the anomalous magnetic moment of the muon. The next part of the thesis examines the phenomenological implications of two models, Pure General Gauge Mediation and the Large Volume Scenario. I fit the models to low energy data and focus on the LHC and dark matter phenomenology, as well as issues of fine-tuning and the structure of the parameter space. In the final chapter I use indirect observables to calculate the Bayesian evidence for specific avatars of supersymmetry breaking from the introduction, using a statistical sampling technique. I discuss the prior dependence of the fits and the effects of the form of dark matter relic density constraint used. I quantify the constraining power and statistical pull of individual observables using the Kullback-Leibler divergence and present the constraints on the parameter space of the minimal anomaly and minimal gauge mediation models.
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Mason, John D. "Aspects of supersymmetry breaking /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2008. http://uclibs.org/PID/11984.
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Kaplan, David Elazzar. "Flavor mediated supersymmetry breaking /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/9729.
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Sun, Zheng. "Supersymmetry breaking from string landscape /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2007. http://uclibs.org/PID/11984.
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Gauntlett, Jerome. "Partial breaking of rigid supersymmetry." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386107.
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Tonioni, Flavio. "Supersymmetry breaking from 4D string moduli." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13531/.
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Il limite di bassa energia della Teoria delle Stringhe può dare luogo a teorie di campo effettive con supersimmetrie N=1 che rappresentano uno scenario molto promettente per la Fisica oltre il Modello Standard. Inoltre, le compattificazioni delle stringhe includono naturalmente meccanismi per la rottura spontanea della supersimmetria nel settore nascosto a causa della stabilizzazione dei moduli. I termini che rompono la simmetria nel visibile (soft supersymmetry breaking terms) sono poi generati attraverso l'interazione gravitazionale tra i moduli e il settore osservabile. La tesi è incentrata sui modelli 4D per le stringhe Type IIB all'interno del cosiddetto LARGE Volume Scenario per la stabilizzazione dei moduli. In particolare, considera compattificazioni di Calabi-Yau di tipo K3 fibrato in cui il Minimal Supersymmetric Standard Model (MSSM) è supportato su brane D7 avvolte su 4-cicli nel regime geometrico. Le correzioni di string loop al potenziale di Kaehler rivestono un ruolo cruciale per la stabilizzazione dei moduli e la rottura della supersimmetria. Inoltre, questa classe di compattificazioni di stringa si è dimostrata particolarmente appropriata per la realizzazione dell'inflazione cosmica. Dopo una discussione sulla forma della metrica di Kaehler per i campi di materia del settore visibile, la tesi determina la struttura dei soft supersymmetry breaking terms risultanti per differenti sistemazioni delle brane. Infine, analizza i principali vincoli fenomenologici sugli spettri di massa del settore nascosto e dei superpartner del Modello Standard, insieme con il requisito dell'ottenimento di una massa dell'Higgs corretta. L'esito finale indica che questa modellizzazione non permette contemporaneamente la presenza di una buona descrizione dell'inflazione e di un settore visibile dato esattamente dall'MSSM. Delle possibili vie d'uscita necessiterebbero o di un modello inflazionario differente o di una estensione minimale dell'MSSM (come il NMSSM).
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Pasti, Paolo, Dmitri Sorokin, Mario Tonin, and sorokin@pd infn it. "Superembeddings, Partial Supersymmetry Breaking and Superbranes." ESI preprints, 2000. ftp://ftp.esi.ac.at/pub/Preprints/esi912.ps.
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Redigolo, Diego. "Supersymmetry Breaking from Holography to Colliders." Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/219162.
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We investigate several aspects of four dimensional supersymmetric gauge theories with the minimal amount of supercharges both from the theoretical and the phenomenological view point. On the theoretical side we investigate the behavior of two-point correlators of short multiplets for vacua that spontaneously break supersymmetry. The main goal is to build up an exhaustive description of the supersymmetry breaking dynamics that it is easily extendable to strongly coupled gauge theories. When strong coupling is involved we study the behavior of two-point correlators by means of AdS/CFT techniques building up models of strongly coupled hidden sectors that break supersymmetry and can be described holographically by gauged supegravity in five dimensions. These hidden sectors have also some phenomenological interest in particle physics beyond the Standard Model since they can be used as supersymmetry-breaking sectors in models where the breaking of supersymmetry is mediated by gauge interactions. On the more phenomenological side we study how the Higgs mass requirements constraints gauge mediation models and what could be possible interesting signatures of these scenarios at LHC.Doctorat en sciences, Spécialisation physique
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Durnford, Callum. "Duality and models of supersymmetry breaking." Thesis, Durham University, 2009. http://etheses.dur.ac.uk/157/.
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Duality is often most clearly manifest in supersymmetric theories, where the rigid mathematical structure affords good control over the behaviour of the system. In many real-world applications, and particularly in particle physics at the TeV scale, supersymmetry can only be present as a broken symmetry. In this thesis we explore various situations in which duality can continue be important when supersymmetry is broken spontaneously, or even explicitly. We first focus on the AdS/CFT correspondence, and consider the effect of instantons in a non-supersymmetric gauge theory obtained via a marginal deformation of N = 4 super Yang-Mills. This gauge theory is expected to be dual to type IIB string theory on a background that is the product of five-dimensional anti-de Sitter spacetime and a deformed five-sphere. By performing an instanton calculation in the deformed gauge theory we extract a prediction for the dilaton-axion field in dual string theory. In the limit of small deformations where the supergravity regime is valid, our instanton result reproduces the expression for the axio-dilaton of the supergravity solution originally found by Frolov, thus supporting the validity of the correspondence. We then go on to look at how supersymmetry breaking in a metastable vacuum allows one to build simple and concrete models of gauge mediation. In the prototypical model of Intriligator, Seiberg and Shih (ISS), Seiberg duality plays an important role in ensuring the longevity of the metastable vacuum. In a move to construct more realistic models we deform the ISS model by adding a baryon term to the superpotential. This simple deformation causes spontaneous breaking of the approximate R-symmetry of the metastable vacuum. We then gauge an SU(5) flavour group and identify it with the parent gauge symmetry of the supersymmetric Standard Model. This implements direct mediation of supersymmetry breaking without the need for an additional messenger sector. A reasonable choice of parameters leads to gaugino masses of the right order. To further explore the phenomenology of metastable susy breaking we distinguish different types of models by the manner in which R-symmetry is broken in the metastable vacuum. In general, there are two possible ways to break R-symmetry: explicitly or spontaneously. We find that the MSSM phenomenology can be greatly affected how this breaking occurs in the Hidden Sector. Explicit R-symmetry breaking models lead to fairly standard gauge mediation patterns, but we argue that in the context of ISS-type models this only makes sense if B = 0 at the mediation scale. This leads to high values of tan beta as a generic prediction. If on the other hand R-symmetry is broken spontaneously, then R-violating soft terms tend to be suppressed with respect to the R-symmetry preserving ones, and one is led to a scenario with large scalar masses. These models interpolate between standard gauge mediation and split SUSY models. We provide benchmark points for the two scenarios, which serve to demonstrate that the specific dynamics of the Hidden Sector - the underlying nature of supersymmetry and R-symmetry breaking - can considerably affect the mass spectrum of the MSSM.
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Macorra, Axel de la. "Supersymmetry breaking in 4D string theory." Thesis, University of Oxford, 1993. http://ora.ox.ac.uk/objects/uuid:0bc6b606-1a02-4d28-b68f-bd5c3ac11d04.
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In this thesis we address the problem of supersymmetry breaking in four dimensional string theory. We derive an effective Lagrangian describing the low energy degrees of freedom including the Goldstone mode associated with the spontaneously broken R-symmetry when a gaugino condensate forms. We show the equivalence between our approach and those previously used for studying gaugino condensate in 4D string theory but we also show the need to include quantum effects due to the strong coupling constant in the hidden sector. We determine the vacuum structure of the complete scalar potential and show that supersymmetry is broken and a large mass hierarchy may develop with a single gaugino condensate. Realistic phenomenological values for the gauge coupling constant, unification scale and soft supersymmetric breaking terms can be obtained. Consistency with the minimal supersymmetric extension of the standard model requires the hidden gauge group to be SU(6) or SO(9).
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Suruliz, Kerim. "Supersymmetry breaking in string theory compactifications." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613191.
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Pasternak, Antoine. "Dimers, Orientifolds, and Dynamical Supersymmetry Breaking." Doctoral thesis, Universite Libre de Bruxelles, 2021. https://dipot.ulb.ac.be/dspace/bitstream/2013/327657/3/Table.pdf.
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This thesis is devoted to the study of orientifolds and dynamical supersymmetry breaking in configurations of D-branes on toric Calabi-Yau singularities, through the lens of dimer models. We first review the basic ingredients of string theory that led to the formulation of gauge/gravity dualities in terms of dimers. Then, we discuss the non-abelian anomaly cancellation conditions for the supersymmetric gauge theories arising on D-branes and provide necessary geometric criteria to determine whether an orientifold projection can be safely introduced. We also find a new realization of orientifold projection without fixed loci in dimer models and expand on its physical features. We argue that it exhausts the possibilities of orientifolding dimer models. In the subsequent part of the thesis, we investigate dynamical supersymmetry breaking vacua in the same class of models and their typical instability along N=2 Coulomb branches. This leads us to formulate a no-go theorem against their stability based on geometrical features of the singularity, and then to establish a precise way to circumvent it. We eventually find the first instance of stable dynamical supersymmetry breaking vacuum in string theory from D-branes on a toric Calabi-Yau singularity, the Octagon.Doctorat en Sciences
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VILLADORO, Giovanni. "Supersymmetry Breaking from Higher-Dimensional Supergravities." Doctoral thesis, La Sapienza, 2006. http://hdl.handle.net/11573/917131.
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Ng, Siew Phang. "New mechanisms for transmission of supersymmetry breaking." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1785.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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McGarrie, Moritz. "Gauge mediated supersymmetry breaking in five dimensions." Thesis, Queen Mary, University of London, 2011. http://qmro.qmul.ac.uk/xmlui/handle/123456789/2427.
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In this thesis we focus on the construction of models in which a supersymmetry breaking hidden sector is located on one fixed point of an extra dimensional interval and the effects are gauge mediated across this interval to the other fixed point where the supersymmetric standard model is located. We use the formalism of current correlators to encode supersymmetry breaking effects and explore flat, warped and deconstructed extra dimensions. We also apply these techniques to models of metastable supersymmetric breaking in N = 1 Supersymmetric Quantum Chromodynamics.
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Chen, Yifan. "Gravity as a playground for supersymmetry breaking." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS060.
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Une simple extension du modèle standard et de la relativité générale consiste à introduire une particule fondamentale de spin 3/2, car il s’agit de la seule pièce manquante entre les spin 0 et 2. En outre, nous ne connaissons qu’un seul candidat présentant un tel spin du point de vue de la théorie fondamentale, le gravitino, superpartenaire du graviton. Ainsi, l’existence d’un spin fondamental 3/2 pourrait également être une arme à feu de supersymétrie ainsi que la théorie des supercordes. L’axion est un autre candidat intéressant au-delà du modèle standard. Pour le problème du CP puissant, l’une des solutions les plus populaires consiste à introduire un axion. La théorie des cordes prédit des particules générales de type axion avec une gamme de masses plus étendue. Ils peuvent également être des candidats parfaits pour la matière noire. Dans cette thèse, nous discutons de leurs mécanismes de production et des signaux possibles pour la détection. Nous souhaitons également aborder certaines questions dans le cadre de la théorie des cordes, telles que la stabilisation des modules. Les travaux précédents utilisent largement les corrections non perturbatives pour générer le minimum pour les champs de modules, tandis que nous choisissons un chemin différent pour rechercher si le problème Dine-Seiberg peut avoir une solution simple. Nous espérons également répondre à la question: pourquoi notre univers observé est-il à quatre dimensions?One simple extension of the Standard Model and general relativity is to introduce a fundamental particle with spin 3/2 since it’s the only missing piece between spin 0 and spin 2. Furthermore, we know only one candidate with such a spin from a fundamental theory point of view, the gravitino, superpartner of the graviton. Thus the existence of a fundamental spin 3/2 could also be a smoking gun of supersymmetry as well as Superstring theory. Another interesting beyond Standard Model candidate is the axion. For the strong CP problem, one of the most popular solution is to introduce an axion. General axion-like particles with a broader range of masses are predicted from String theory. They can be perfect cold dark matter candidates as well. In this thesis, we discuss their production mechanisms and possible signals for detection. We also want to address some questions in the framework of String theory like moduli stabilisation. Previous works widely use non-perturbative corrections to generate minimum for moduli fields while we choose a different path to investigate if the Dine-Seiberg problem can have a simple solution. We also hope to answer the question: why our observed universe is four-dimensional?
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Omura, Yuji. "Supersymmetry breaking, R-symmetry, and conformal dynamics." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/124410.
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Diego, Castro David. "Supersymmetry and electroweak symmetry breaking from extra dimensions." Doctoral thesis, Universitat Autònoma de Barcelona, 2008. http://hdl.handle.net/10803/3408.
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La tesis, que lleva por título "Supersymmetry and ElectroWeak Symmetry Breaking from Extra Dimensions" y que ha sido realizada por David Diego bajo la supervisión del Dr. Mariano Quirós, consiste principalmente en la aplicación de modelos supersimétricos, desarrollados en cinco dimensiones, sobre algunos aspectos fenomenológicos relacionados con la física más allá del Modelo Estándar, como por ejemplo: La rotura de la simetría Electro-Débil (EWSB) y el origen y naturaleza de la masa de los neutrinos. De hecho, estos dos son los temas centrales de la tesis. La estructura de la misma se muestra a continuación: Tras una breve introducción histórica en el concepto de supersymetría, los siguientes dos capítulos se destinan a la construcción de las llamadas algebras de supersimetría y a su realización a nivel de teoría de campos, correspondiendo al capítulo 2, así como al proceso de compactificación de dimensiones extra y rotura de supersimetría, desarrollado en el capítulo 3. Al respecto de estos dos capítulos introductorios cabe resaltar que debido a la rigurosidad que se ha intentado aportar a la exposición, la lectura puede resultar un tanto técnica en algunos momentos.
El capítulo 4, no obstante, no es enteramente introductorio. En él se presenta un ejemplo de teoría supersimétrica en un espacio Lorentziano de cinco dimensiones compactificado a un orbifold (ver capítulo 3). Tal teoría se utiliza como modelo para describir el doblete de bosones de Higgs con términos de masa impares extendidos en todo el 5volumen. Tales masas inducen (dinámicamente) una localización hacia los puntos fijos de algunos de los modos admitidos por el modelo lo que provoca, a su vez, un supresión exponencial en el valor de la masa de los correspondientes modos. Estos últimos podrían utilizarse como los dobletes de bosones de Higgs en el MSSM para inducir la rotura Electro-Débil.
El capítulo 5 se corresponde con la publicación JHEP 0511:008,2005 en colaboración con M. Quirós y G.v. Gersdorff. En este trabajo se cambia el punto el enfoque desarrollando el modelo en el intervalo, esto es: una variedad de dimensión 5 con fronteras de dimensión 4 y cuya quinta coordenada tiene un tamao de unos pocos TeV−1 . Se plantea, pues, una acción libre con términos de frontera de tipo masa y se muestran las condiciones de contorno, que se obtienen dinámicamente. La supersimetría se rompe por la presencia de los términos de frontera y se muestra que la ecuación del espectro admite modos tachyonicos (valores imaginarios para la masa), lo cual es interesante por sí mismo, ya que pudrían ser utilizados pra inducir la rotura Electro-Débil mediante correcciones radiativas, lo que se corrobora en el capítulo 7, con pequeas modificaciones en el modelo.
Este modelo está enteramente desarrollado en el llamado formalismo real, que consiste en doblar los grados de libertad para luego imponer condiciones de realidad sobre los campos ya que en este formalismo los términos de frontera resultan fácilmente expresables si bien las interacciones (indispensables para el estudio del comportamiento cuántico del modelo) no lo son tanto, y por ello en el capítulo 6 presentamos un diccionario entre el formalismo real y el más habitual formalismo de supercampos. Este es un trabajo que está pendiente de publicación.
En el capítulo 7 se generaliza el anterior modelo, en formalismo de supercampos, con términos de frontera de tipo masa arbitrarios. La supersimetría se rompe mediante las condiciones de contorno de una manera análoga al mecanismo de Scherk-Schwarz. El espectro aún admite tachyones y la rotura Electro-Débil se induce mediante las correcciones radiativas precisando un pequeo ajuste de los parámetros del modelo. Este capítulo plasma los principales resultados del trabajo Phys.Rev.D74:055004,2006, de nuevo en colaboracion con M. Quirós and G.v. Gersdorff.
Con aquél mismo tipo de modelos, en el capítulo 8 se investiga exhaustivamente la posibilidad de generar masas muy ligeras para los neutrinos permitiendo que el neutrino destrógiro (RH) se propaga en todo el volumen con masa M y condiciones de frontera arbitrarias. Se encuentra que en el caso general el modelo predice una masa de tipo Majorana ultra ligera (en el rango del eV) mientras que para una configuración volumen-frontera particular, aparece una simetría U(1) global que protege el número leptónico y de esta manera el modelo predice una masa de tipo Dirac exponencialmente suprimida por la masa del neutrino destrógiro. Este último trabajo se corresponde con la publicación «Nucl. Phys. B805:148-167,2008.
Finalmente, el último capıtulo se destina a las conclusiones de la tesis.
The thesis titled "Supersymmetry and ElectroWeak Symmetry Breaking from Extra Dimensions" and developed by David Diego under the supervision of Dr. Mariano Quir«os mainly consists in the application of supersymmetry in extradimensional models to some phenomenological aspects of Physics beyond the Standard Model such as ElectroWeak Symmetry Breaking (EWSB) and neutrino masses. Actually these are the central questions around which the research work gravitates. The structure of the thesis is summarized in the following:
After a brief historical introduction on the concept of supersymmetry, the next two chapters are dedicated to review the construction of the so called supersymmetric algebras and their realizations at the level of field theories, corresponding to chapter 2, and the process of compactification of extra dimensions and supersymmetry breaking, which will be worked out in chapter 3. Concerning these introductory chapters we should remark that in our attempt to present a rigorous exposition, the discussion may become rather technical at some point.
Chapter 4 is not completely introductory. It is devoted to present an example of supersymmetric theory in a five dimensional space time compactified on an orbifold (see chapter 3). There it is presented a model for Higgs doublets with odd bulk masses which dynamically localize some of the modes predicted by the spectrum equation and exponentially suppress the lowest value of the physical spectrum. These lowest values may be used as the MSSM Higgs doublet that triggers the EWSB.
Chapter 5 corresponds to the publication JHEP 0511:008,2005 in collaboration with M. Quir«os and G.v. Gersdorff. Here we change the point of view and work in the interval rather than in the orbifold, that is just with a 5D manifold with 4D boundaries where the fifth coordinate is of size of few TeV−1 . A free action with boundary terms is constructed and the boundary conditions, which are dynamically obtained, are written down. The supersymmetry is broken by boundary conditions and it is shown that the spectrum predicted by the model admits a tachyonic mode (imaginary values for the mass) which is interesting by itself since it could be used to trigger the EWSB with radiative corrections which is verified in chapter 7, with a slight modification in the model.
These model was entirely developed within what is called real formalism which consists in doubling the off-shell degrees of freedom and then imposing reality constraints. The boundary terms turns out to be written easier in that formalism rather than in the usual superfield approach. However the interaction terms, needed to check the quantum behavior of the theory, are harder derivable and thus in chapter 6 we translate the whole model in terms of superfields showing the equivalence between the two formalisms. This is a work to be submitted.
In chapter 7 we generalize the previous model within superfield formalism with general mass-like boundary terms. Supersymmetry is broken by the boundary conditions a la -Scherk-Schwarz. The spectrum still presents a tachyon mode although its origin is slightly different from the one appearing in chapter 5 and the EWSB is induced by radiative corrections with a tiny fine tuning of the parameters. This chapter presents the main results found in the publication Phys.Rev.D74:055004,2006, again in collaboration with M. Quir«os and G.v. Gersdorff.
Within the same class of models, in chapter 8 we exhaustively investigate the possibility for getting an ultra light mass for neutrinos by letting the right handed neutrino to propagate in the five dimensional bulk with bulk mass M and arbitrary mass-like boundary terms. We find that in the general case the model yields a sub-eV Majorana mass for the SM left handed neutrinos. There is, however, a particular bulk-boundary configuration where a global U(1) symmetry arises and prevents the lepton number from being violated, yielding thus a Dirac mass connecting left and right handed neutrinos, whose value is exponentially suppressed by the bulk right handed neutrino mass. This work has been done in collaboration with M. Quir«os and its reference is Nucl. Phys. B805:148-167,2008.
Finally in the last chapter we present the conclusions of the thesis.
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Angelantonj, Carlo, Ralph Blumenhagen, Matthias R. Gaberdiel, and blumenha@physik hu-berlin de. "Asymmetric Orientifolds, Brane Supersymmetry Breaking and Non--BPS." ESI preprints, 2000. ftp://ftp.esi.ac.at/pub/Preprints/esi905.ps.
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Barnard, James. "Degrees of metastability in gauge mediated supersymmetry breaking." Thesis, Durham University, 2011. http://etheses.dur.ac.uk/3209/.
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This thesis consists of an investigation into supersymmetry and its breaking. Emphasis is placed on the question of metastability and the role of non-topological solitons in the hidden sector. A desirable feature in models employing direct gauge mediation is that of tree level metastability, in order to generate large enough gaugino masses. An explicit realisation of this idea is constructed via a simple deformation of SQCD that is well motivated and needs no fine tuning. Any viable metastable supersymmetry breaking vacuum must also be stable enough to survive until the present day. Non-topological solitons, or Q-balls, are supported in all such vacua where there is a conserved, global U(1) symmetry and no massless, charged scalars. It is shown that for a broad class of models Q-balls are extremely influential on the vacuum lifetime and make seemingly viable vacua catastrophically short lived. Even when there is no effect on vacuum stability flat directions charged under an R-symmetry are a ubiquitous feature of O’Raifeartaigh models. Non-topological solitons associated with this symmetry, R-balls, are likely to form through the fragmentation of a condensate. Their cosmology is studied and it is found that they can have significant observable effects, from acting as a good dark matter candidate to providing the primary source of reheating in the early universe.
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Grellscheid, D. "Discrimination of supersymmetry breaking models from sparticle spectra." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599697.
Full textAbstract:
It is widely expected that over the next few years some evidence of low-energy super-symmetry (SUSY) will be found at collider experiments such as LHC, the Tevatron or a linear collider. This discovery would constitute a significant step in closing the current conceptual gap between experimental observations and proposed fundamental theories, which all make varying predictions about the mechanisms of SUSY breaking and the spectrum of resulting superparticles (sparticles). The focus of the search will therefore soon shift from the discovery of SUSY to more detailed studies of the proposed models of SUSY and SUSY breaking which would make it possible to select or rule out some models. Rather than analyzing the observable consequences of single points in the parameter space of SUSY breaking in detail, or reconstructing SUSY breaking parameters from low scale observables, I will present a procedure aiming to look at various models of SUSY breaking simultaneously. It does so by scanning over wide ranges of their input parameters to create an experimental footprint of each model in “measurement space”. The distance between these footprints gives a direct indication of the minimal set of measurements that is required to separate the models. This makes it possible to decide a priori whether two high scale models can be distinguished experimentally, and what measurement accuracy is necessary to do so. This procedure will be shown in a model scenario motivated by Type I string models. As soon as more than two dimensions are considered in the measurement space, it becomes impossible to obtain the spacing between the footprints by eye. Automatic techniques to judge the separation become necessary; a discussion of these, including the most promising one based on Genetic Algorithms, constitutes the latter part of this thesis.
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Dent, Thomas Edward. "CP violation and supersymmetry-breaking in superstring models." Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323022.
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Muia, Francesco <1987>. "Sequestered String Models: Supersymmetry Breaking and Cosmological Applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7274/1/Muia_Francesco_Tesi.pdf.
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In the present thesis I focused on the study of the phenomenology arising from a class of string models called sequestered compactifications, which were born with the aim of getting low-energy SUSY from strings. This is not an easy task if combined with cosmological constraints, since the mechanism of moduli stabilization fixes both the scale of supersymmetric particles and the scale of moduli, which tend to be of the same order. However, if on the one hand supersymmetric particles with TeV mass are desired in order to address the electroweak hierarchy problem, on the
other hand the cosmological moduli problem requires the moduli to be heavier than 100 TeV. The specific setup of sequestered compactifications makes this hierarchy
achievable, at least in principle: as in these models the visible sector is located on a stack of D3-branes at singularities, a physical separation between the visible degrees of freedom and the SUSY-breaking sources takes place. Such decoupling translates into a hierarchy between the scale of SUSY-breaking and the spectrum of supersymmetric particles. Interestingly, moduli are the four-dimensional manifestation of the existence of extra-dimensions. Since they are only gravitationally coupled,
they could decay late in the history of the universe, affecting in a significant way its cosmological evolution. Possible deviations of the cosmological observables from
the values predicted by the standard Hot Big Bang Theory constitute an interesting alternative for the discovery of new physics beyond the Standard Model, which is complementary to the particle physics search. For this reason in addition to SUSY-breaking in sequestered models, I also studied several cosmological scenarios arising
from them, such as production of non-thermal dark matter and dark radiation, reheating from moduli decay and inflation.
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Muia, Francesco <1987>. "Sequestered String Models: Supersymmetry Breaking and Cosmological Applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7274/.
Full textAbstract:
In the present thesis I focused on the study of the phenomenology arising from a class of string models called sequestered compactifications, which were born with the aim of getting low-energy SUSY from strings. This is not an easy task if combined with cosmological constraints, since the mechanism of moduli stabilization fixes both the scale of supersymmetric particles and the scale of moduli, which tend to be of the same order. However, if on the one hand supersymmetric particles with TeV mass are desired in order to address the electroweak hierarchy problem, on the
other hand the cosmological moduli problem requires the moduli to be heavier than 100 TeV. The specific setup of sequestered compactifications makes this hierarchy
achievable, at least in principle: as in these models the visible sector is located on a stack of D3-branes at singularities, a physical separation between the visible degrees of freedom and the SUSY-breaking sources takes place. Such decoupling translates into a hierarchy between the scale of SUSY-breaking and the spectrum of supersymmetric particles. Interestingly, moduli are the four-dimensional manifestation of the existence of extra-dimensions. Since they are only gravitationally coupled,
they could decay late in the history of the universe, affecting in a significant way its cosmological evolution. Possible deviations of the cosmological observables from
the values predicted by the standard Hot Big Bang Theory constitute an interesting alternative for the discovery of new physics beyond the Standard Model, which is complementary to the particle physics search. For this reason in addition to SUSY-breaking in sequestered models, I also studied several cosmological scenarios arising
from them, such as production of non-thermal dark matter and dark radiation, reheating from moduli decay and inflation.
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Friden, Eric. "It's pretty super! : A Mathematical Study of Superspace in Fourdimensional, Unextended Supersymmetry." Thesis, Uppsala universitet, Teoretisk fysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-181048.
Full textAbstract:
Superspace is a fundamental tool in the study of supersymmetry, one that while often used is seldom defined with a proper amount of mathematical rigor. This paper examines superspace and presents three different constructions of it; the original by Abdus Salam and J. Strathdee as well as two modern methods by Alice Rogers and Buchbinder-Kuzenko.Though the structures arrived at are the same the two modern constructions differ in methods, elucidating different important aspects of super-space. Rogers focuses on the underlying structure through the study of supermanifolds, and Buchbinder-Kuzenko the direct correlation with the Poincare superalgebra, and the parametrisation in terms of exponents.
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Cotellucci, Alessandro. "Flavour constraints on sequestered supersymmetry breaking in string models." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21709/.
Full textAbstract:
The Standard Model (SM) is the best theory which describes Nature at the fundamental level. Even if it provides very accurate predictions, the SM features some open problems. A promising extension of the SM is the Minimal Supersymmetric Standard Model (MSSM) provided by supersymmetry. The MSSM can provide solutions for some of the open problems of the SM but it can suffer from the flavour supersymmetric problem associated with the presence of large Flavour Changing Neutral Currents (FCNCs). The flavour supersymmetric problem is related to the mechanism which mediates supersymmetry breaking from the hidden to the visible MSSM sector. A popular supersymmetry breaking mediation mechanism is gravity mediation but generic gravity mediated models lead to large FCNCs. The conditions to avoid FCNCs in gravity mediated models are called mirror mediation. These conditions can naturally be satisfied in 4D string compactifications. 4D string models introduce new scalar particles, the moduli, which interact gravitationally with matter and represent natural candidates to mediate supersymmetry breaking to the MSSM. Promising 4D string scenarios are sequestered models where the MSSM lives on branes at singularities and the visible sector is sequestered from the sources of supersymmetry breaking in the bulk of the extra dimensions. So one can realise low-energy supersymmetry and all moduli can be heavy enough to avoid any cosmological moduli problem. In this thesis we shall focus on 4D sequestered string scenarios and determine which models can reproduce mirror mediation without the production of large FCNCs. We will find two different classes of sequestered models where only one can be compatible with present flavour constraints on FCNCs. This comparison with observations will provide information on important details of the microscopic theory like the functional dependence on the extra-dimensional volume of the physical Yukawa couplings and the Kähler potential for matter fields.
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Knochel, Alexander Karl. "Supersymmetry in a Sector of Higgsless Electroweak Symmetry Breaking." Doctoral thesis, kostenfrei, 2009. http://www.opus-bayern.de/uni-wuerzburg/volltexte/2010/4789/.
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West, Stephen Mathew. "Neutrino masses, leptogenesis and dark matter from supersymmetry breaking." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491611.
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In this thesis, we analyse a class of supersymmetric models first introduced by ArkaniHamed et al and Borzumati et al. in which the light neutrino masses result from higherdimensional supersymmetry-breaking terms in the M88M super- and Kahler-potentials. The mechanism is closely related to the Giudice-Masiero mechanism for the M88M p, parameter, and leads to TeV-scale right-handed neutrino and sneutrino states. The dominant contribution to the light neutrino (Majorana) mass matrix is a one-loop term with a sub-dominant tree-level 'see-saw' contribution which may lead to interesting perturbations of the leading flavour structure, possibly generating the small ratio !:lm;olarl!:lm~tm dynamically. Using this mechanism it is also possible to construct a natural model of TeV-scale resonant leptogenesis. The model leads to large cosmological lepton asymmetries via the resonant behaviour of the one-loop self-energy contribution to the right-handed neutrino (Ni ) decay. This model addresses the primary problems of previous phenomenological studies of low-energy leptogenesis: a rational for TeV-scale right-handed neutrinos with small Yukawa couplings so that the out-of equilibrium condition for Ni decay is satisfied; the origin of the tiny, but non-zero mass splitting required between at least t,vo Ni masses; and the necessary non-trivial breaking of flavour symmetries in the right-handed neutrino sector. Following this, a weakly broken gauged 80(3) flavour symmetry is used to produce. two highly-degenerate right-handed neutrinos. It is shown that this 80(3) flavour symmetry is compatible with all fermion masses and mixings if it is supplemented with a further 8U(3) flavour symmetry. This mechanism is then embedded into the model of neutrino masses and leptogenesis described above. Lastly, we investigate why the inferred values of the cosmological baryon and dark matter densities are so strikingly similar. We consider models of dark matter possessing a particle-antiparticle asymmetry where this asymmetry determines both the baryon asymmetry and strongly effects the dark matter density, thus naturally linking Ob and 0dm. We show that sneutrinos can play the role of such dark matter.
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Larose-Filotas, Elise. "N = 2 partial supersymmetry breaking in brane-world scenarios." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79025.
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We describe brane-world models which partially break supersymmetry from N = 2 to N = 1. The brane models we consider are embedded within a 4-dimensional N = 2 locally supersymmetric bulk-space. We devise the following models: a single-brane action, a single-antibrane action and a two-brane action. In these models the membrane linearly realises one supersymmetry of the bulk and spontaneously breaks the other. We also construct the action for a brane free bulk with a cosmological constant term. This model is different from the previous examples because both supersymmetries are broken. We also attempt to devise a brane-antibrane action. This model has the particular feature of breaking both supersymmetries of the bulk-space. Effects of this investigation on our understanding of the mechanism of partial supersymmetry breaking in brane-world scenarios will be discussed. In particular, the contribution to the cosmological constant via this mechanism will be examined. In order to construct such a model, we use the previous actions and the concepts developed throughout their construction. This investigation constitutes a firm foundation toward the construction of a successful brane-antibrane model.
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Matos, Luis Filipe Pinto T. A. "Supersymmetry breaking : models of gauge mediation with gauge messengers." Thesis, Durham University, 2010. http://etheses.dur.ac.uk/553/.
Full textAbstract:
With the start of the LHC, it becomes increasingly important to understand the experimental signatures that discriminate different extensions of the standard model. Supersymmetry (SUSY), in particular the Minimal Supersymmetric Standard Model (MSSM), is one such extension that is specially attractive by its simplicity and elegance. However, if this symmetry is to be realized in nature, it must be spontaneously broken. In this work we will try to understand the most general way in which SUSY breaking can happen in renormalizable field theories and the implications that this has on the minimal extension of the standard model (MSSM) mass spectrum. The first two chapters are the introductory material: in chapter 1 we will introduce some of the key ideas necessary to understand supersymmetric field theories, and in chapter 2 we will briefly describe the the simplest supersymmetric version of the Standard Model. In chapter 3 we will focus on understanding the role of R-Symmetry breaking in determining the soft terms gauge mediation of supersymmetry breaking (GMSB) can lead to. To do this we consider a model where both R-symmetry and SUSY are spontaneously broken. One starts with the model proposed by Intriligator, Seiberg and Shih (ISS) and adds a (dangerous) marginal operator, which we call a meson deformation. The inclusion of this operator leads to the spontaneous breaking of R-symmetry in the vacuum. One then gauges the SU(5) of flavour and identifies it with the MSSM GUT gauge group, thus implementing GMSB. This was the second explicit example where R-symmetry was spontaneously broken in the vacuum. As in the first, gaugino masses iii turned out to be smaller than naively expected so that a mild splitting between scalar (squark and slepton) and gaugino masses exists. After this, a general argument showed that in fact gaugino masses are always significantly smaller than scalar masses if the universe is perturbatively stable. This arguments suggests that any viable vacuum should be (perturbatively) metastable, as had been previously noticed by Murayama and Nomura. In chapter 4, we try to explore alternatives to this scenario by considering the possibility that the vacuum doesn’t break supersymmetry by F-term vevs alone, but by a having simultaneously non-zero F and D-terms. It turns out that this does not happen in models where the Kahler potential is canonical, and the superpotential is a cubic polynomial in the fields, but it can happen if either of these constraints is violated. This leads us to consider a particular example, where we study a hidden sector model with SU(3) gauge group, two flavours of quarks and one singlet. The superpotential is the most general consistent with the tree-level symmetries. The R-symmetry is anomalous, however, but one can still derive selection rules that constrain the form of the effective superpotential. The only extra term that is allowed is an instanton induced contribution. This term explicitly breaks the R-symmetry, but the resulting low energy superpotential is not generic and SUSY is still spontaneously broken. While not a complete example of GMSB, this class of hidden sector models is interesting as it does not require metastability: the tension between the spontaneous breaking of an R-symmetry and the massless R-axion is bypassed by the naturally non-generic superpotential. These models usually have both F and D-term SUSY breaking, but these two vevs are not independent: in non-Abelian theories, the D-term vevs can only be induced by the F-term vevs of fields that are not gauge singlets. The implementation of GMSB in scenarios where the F-terms are not gauge singlets is then considered in both its direct and semi-direct forms: iv In chapter 5 we deal with direct gauge mediation with gauge messengers. In this version of gauge mediation, the spontaneously broken gauge group is identified with the MSSM GUT gauge group and generically leads to tachyonic squark or slepton masses. In the particular case where the GUT gauge group is SU(5), we show that this problem can be solved if there are two independent sectors where SUSY is spontaneously broken or simply by using a solution of the doublet-triplet splitting problem where the vev responsible for the spontaneous breaking of the GUT symmetry is larger than the SUSY breaking scale. In both cases the effects gauge and non-gauge messengers have to combine if a viable spectrum is to be reached. We then finish out study in chapter 6 by considering the semi-direct version of gauge mediation with gauge messengers. As it is known, gaugino masses are screened from messenger interactions, at leading order in the SUSY breaking parameter F. Because of this, gaugino soft masses will be suppressed with respect to scalar soft masses. This leads to a scenario of mildly split SUSY, i.e. scalars are at least one or two orders of magnitude heavier than gauginos. This generically leads to some extra fine-tuning to get the EW breaking scale to occur at the correct scale.
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Setzer, Nicholas. "[nu] Seesaw uses UV insensitive supersymmetry breaking without tachyons /." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8484.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Physics. Title from t.p. of PDF. On title page "nu" is represented by its Greek letter. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Puolamäki, Kai. "Breaking of R-parity and supersymmetry in supersymmetric models." Helsinki : University of Helsinki, 2001. http://ethesis.helsinki.fi/julkaisut/eri/fysii/vk/puolamaki/.
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Mondadori, Tommaso. "Moduli stabilisation and soft supersymmetry breaking in string compactifications." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8940/.
Full textAbstract:
In this thesis, we shall work in the framework of type IIB Calabi-Yau flux compactifications and present a detailed review of moduli stabilisation studying in particular the phenomenological implications of the LARGE-volume scenario (LVS). All the physical relevant quantities such as moduli masses and soft-terms, are computed and compared to the phenomenological constraints that today guide the research.
The structure of this thesis is the following.
The first chapter introduces the reader to the fundamental concepts that are essentially supersymmetry-breaking, supergravity and string moduli, which represent the basic framework of our discussion.
In the second chapter we focus our attention on the subject of moduli stabilisation. Starting from the structure of the supergravity scalar potential, we point out the main features of moduli dynamics, we analyse the KKLT and LARGE-volume scenario and we compute moduli masses and couplings to photons which play an important role in the early-universe evolution since they are strictly related to the decay rate of moduli particles.
The third chapter is then dedicated to the calculation of soft-terms, which arise dynamically from gravitational interactions when moduli acquire a non-zero vacuum expectation value (VeV).
In the last chapter, finally, we summarize and discuss our results, underling their phenomenological aspects. Moreover, in the last section we analyse the implications of the outcomes for standard cosmology, with particular interest in the cosmological moduli problem.
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BIANCHI, MARCO STEFANO. "Superspace computation 3D." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2011. http://hdl.handle.net/10281/27052.
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In my thesis I describe applications of superspace techniques to perturbative aspects of supersymmetric field theories in three dimensions. Namely I discuss the computation of the exactly marginal deformations of three dimensional Chern-Simons conformal field theories, and then I focus on the computation of scattering amplitudes in the ABJM model.
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Goto, Yoshinori. "Partial Breaking of Global Supersymmetry in Linear and Nonlinear Models." Kyoto University, 2000. http://hdl.handle.net/2433/181020.
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Kyoto University (京都大学)0048
新制・課程博士
博士(人間・環境学)
甲第8453号
人博第83号
11||151(吉田南総合図書館)
新制||人||21(附属図書館)
UT51-2000-F357
京都大学大学院人間・環境学研究科人間・環境学専攻
(主査)教授 植松 恒夫, 教授 松田 哲, 教授 青山 秀明
学位規則第4条第1項該当
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Hodgson, Richard Garth. "Realistic models of low energy physics from anomaly mediated supersymmetry breaking." Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507178.
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Abdussalam, S. S. "Bottom-up and top-down approaches to low energy supersymmetry breaking." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595324.
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In this thesis we address the phenomenology of SUSY breaking from the superstring scale to the electroweak scale in order to produce a guide map for discovery at the LHC. From the top-down approach we study SUSY breaking at low-energies from a well defined superstring theory scenario and extract its phenomenological implications. From the bottom-up approach (independent of string theory), using Bayesian inference techniques, we make the first complete model-independent scan of the low energy phenomenological MSSM (pMSSM) parameter space. We perform the first statistically convergent pMSSM global fit to all current collider and DM data. We demonstrate the application of Bayesian model selection methodology to high energy SUSY breaking models with modest number of free parameters. We found that SUSY breaking from superstring theory should eventually help test its reality and that direct data is required in order to assign unambiguous preferences between different high energy SUSY breaking models. We predict that the Higgs boson mass lies between 117 GeV and 128 GeV at 95% confidence level. We believe this is a robust prediction that should be confirmed once SUSY is discovered at the LHC. Our pMSSM parameters fit provides an appropriate arena for the LHC studies of the MSSM which we wish to pursue further in future work.
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Williams, Mobolaji (Mobolaji O. ). "Pseudo-goldstino to gravitino decay : an implication of multiple supersymmetry breaking." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83778.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 67-68).
This thesis studies the decay of a pseudo-goldstino to a gravitino plus a photon in the Minimal Supersymmetric Standard Model. The foundational premise of this decay process is that there are two independent sectors of supersymmetry breaking. We compute this main decay rate using the goldstino equivalence theorem to replace the final gravitino state with a goldstino. This replacement allows us to study simpler models which help build the intuition and methods for the final calculation. Specifically, we first study the decay of a pseudo-goldstino to a goldstino plus a photon in a toy model of multiple supersymmetry breaking and then the same process in the Minimal Supersymmetric Standard Model without supergravity. Incorporating supergravity introduces the interpretation of the goldstino as the longitudinal component of the gravitino and introduces the constant mass ratio between the gravitino and the pseudo-goldstino which is definitive of multiple local supersymmetry breaking. For the main decay process, we find that the rate is zero for certain relationships between the parameters which define the two hidden sectors. In the discussion we suggest other similar calculations which can be done within the same framework.
by Mobolaji Williams.
S.B.
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Catino, Francesca. "Supersymmetry-breaking vacua in simple and extended supergravity and flux compactifications." Doctoral thesis, Università degli studi di Padova, 2012. http://hdl.handle.net/11577/3422963.
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The search for semi-realistic supergravity models, seen as the low-energy limit of superstring theory, strongly motivates the study of gauged supergravities and flux compactifications. Outstanding problems in this context are supersymmetry breaking, moduli stabilization and the generation of a small positive vacuum energy density. Whilst spontaneously broken N=1 supergravity is the only phenomenologically viable possibility in four dimensions, its vast arbitrariness is significantly reduced when considering consistent truncations of extended supergravities or, more generally, effective theories of flux compactifications. In this thesis we explore some aspects of supersymmetry breaking for which the constrained theoretical frameworks of extended supergravities and of flux compactifications play an important role. We begin by reviewing the basic structure of four-dimensional supergravities and of flux compactifications of the higher-dimensional ones. We then describe some original work on Fayet-Iliopoulos (FI) terms and de Sitter (dS) vacua: we introduce a novel distinction between genuine FI terms and impostors; we formulate a simple anomaly-free model with a genuine FI term, a classically stable dS vacuum and no global symmetries; we explore the relations between N=1 FI terms and their counterparts in extended supergravities, by discussing suitable truncations of the latter. We continue with other original work on the relation between M-theory compactifications with geometrical and non-geometrical fluxes, gauged N=8 supergravity in four dimensions and consistent N=1 truncations of the latter. In particular: we discuss the quadratic constraints on general fluxes in M-theory, relating them with the conditions on the embedding tensor that defines the gauged N=8 theory; we identify the fluxes generating four-parameter supersymmetry breaking à la Scherk-Schwarz, and comment on the one-loop stability of the resulting Minkowski background.La ricerca di modelli semi-realistici di supergravità, visti come limite di bassa energia delle teorie di superstring, motivano fortemente lo studio delle teorie di supergravità con gruppi di gauge non banali e delle compattificazioni con flussi. In questo contesto, problemi ancora aperti sono la rottura di supersimmetria, la stabilizzazione dei moduli e la generazione di densità di energia del vuoto piccola e positiva. Nonostante la supergravità N=1 con supersimmetria spontaneamente rotta sia l'unica possibilità fenomenologicamente valida in quattro dimensioni, la sua vasta arbitrarietà viene significativamente ridotta quando si considerano troncazioni consistenti di supergravità estese o, più in generale, le teorie efficaci di compattificazioni con flussi. In questa tesi si esplorano alcuni aspetti della rottura di supersimmetria in cui un ruolo importante \`e giocato dalla struttura teorica vincolata delle supergravità estese e delle compattificazioni con flussi. Si inizia con una breve rassegna sulle strutture basilari delle supergravità in quattro dimensioni e delle compattificazioni con flussi di modelli di supergravità formulati in dimensione più alta. Successivamente si descrive del lavoro originale sui termini di Fayet-Iliopoulos (FI) ed i vuoti di de Sitter (dS): si introduce una nuova distinzione tra termini di FI genuini e 'impostori'; si formula un semplice modello senza anomalie con un termine di FI genuino, un vuoto di dS classicamente stabile e senza simmetrie globali; si analizzano le relazioni tra i termini di FI N=1 e le loro controparti nelle supergravità estese, discutendo opportune troncazioni di queste ultime. Si prosegue poi con dell'altro lavoro originale sulla relazione tra le compattificazioni di M-teoria con flussi geometrici e non-geometrici, le teorie di supergravità N=8 in quattro dimensioni con gruppi di gauge non banali e le troncazioni consistenti di queste ultime a N=1. In particolare: si discutono i vincoli quadratici su tutti i flussi in M-teoria, collegandoli con le condizioni sul tensore di embedding che definisce la teoria di gauge N=8; si identificano i flussi che generano la rottura di supersimmetria à la Scherk-Schwarz con quattro parametri, e si commenta sulla stabilità a un loop del risultante vuoto di Minkowski.
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de, lechtenf@itp uni-hannover. "N=(2$|$2) Supersymmetric Toda Lattice Hierarchy in N=(2$|$2) Superspace." J. Nonlinear Math. Phys. 8 (2001) 183-195, 2000. ftp://ftp.esi.ac.at/pub/Preprints/esi913.ps.
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McCarthy, Shane A. "Topics in nonlinear self-dual supersymmetric theories." University of Western Australia. School of Physics, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0045.
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[Truncated abstract. Formulae and special characters can only be approximated. See PDF version for accurate reproduction.] Theories of self-dual supersymmetric nonlinear electrodynamics are generalized to a curved superspace of 4D N = 1 supergravity, for both the old-minimal and the newminimal versions of N = 1 supergravity. We derive the self-duality equation, which has to be satisfied by the action functional of any U(1) duality invariant model of a massless vector multiplet, and show that such models are invariant under a superfield Legendre transformation. We construct a family of self-dual nonlinear models, which includes a minimal curved superspace extension of the N = 1 supersymmetric Born- Infeld action. The supercurrent and supertrace of such models are explicitly derived and proved to be duality invariant. The requirement of nonlinear self-duality turns out to yield nontrivial couplings of the vector multiplet to Kähler sigma models. We explicitly construct such couplings in the case when the matter chiral multiplets are inert under the duality rotations, and more specifically to the dilaton-axion chiral multiplet when the group of duality rotations is enhanced to SL(2,R). The component structure of the nonlinear dynamical systems introduced proves to be more complicated, especially in the presence of supergravity, as compared with well-studied effective supersymmetric theories containing at most two derivatives (including nonlinear Kähler sigma-models). As a result, when deriving their canonically normalized component actions, the traditional approach becomes impractical and cumbersome. We find it more efficient to follow the Kugo-Uehara scheme which consists of (i) extending the superfield theory to a super-Weyl invariant system; and then (ii) applying a plain component reduction along with imposing a suitable super-Weyl gauge condition. This scheme is implemented in order to derive the bosonic action of the SL(2,R) duality invariant coupling to the dilaton-axion chiral multiplet and a Kähler sigma-model.
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Kelly, Mandy Sharon. "A search for gauge mediated supersymmetry breaking using signal e'+e'-#->#." Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301725.
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Jones, Jeff L. "Direct gauge mediation of supersymmetry breaking with a strongly coupled hidden sector /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2009. http://uclibs.org/PID/11984.
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Cribiori, Niccolò. "Non-linear realisations in global and local supersymmetry." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3424921.
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In modern physics the role of symmetries is central and, even when they are broken, their remnants can pose constraints on the interactions. In considering effective descriptions of certain physical models, the symmetry group can be indeed spontaneously broken to some subgroup, but it is still possible to write symmetry transformations which leave a given action invariant. These transformations are usually realised non-linearly on the fields, while in the unbroken regime they act linearly.
The Standard Model of particle physics can be though of as an effective theory. In this respect, beyond the Standard Model scenarios have been proposed, of which supersymmetry is one of the best motivated at present. Having been yet no direct detection in the experiments, supersymmetry is postulated to be spontaneously broken at some energy scale above the TeV. For this reason, it is important to study supersymmetry breaking mechanisms and to consider low energy effective theories with spontaneously broken and non-linearly realised supersymmetry.
An essential ingredient of this class of models is the presence of a massless goldstone fermion in the spectrum, namely a goldstino, which is associated to each broken generator.
The subject of this thesis is the construction and the study of four-dimensional effective theories with spontaneously broken and non-linearly realised global and local supersymmetry. In the first part, the global supersymmetric case is analysed. The discussion starts from the supersymmetry breaking sector, describing the goldstino and its interactions, in the case of minimal supersymmetry and it is then generalised to a generic number of spontaneously broken supersymmetry generators.
A systematic procedure is given in order to construct effective theories with non-linearly realised supersymmetry and with any desired spectrum content. In the second part of the thesis, non-linear realisations are analysed in the case of local supersymmetry, namely supergravity. The coupling of the goldstino sector to gravity is presented first and the superhiggs mechanism on a generic background is discussed. Matter couplings are then constructed in some simple examples. A new class of models is introduced in which supersymmetry is spontaneously broken and non-linearly realised already on the gravity sector. As a consequence, it is possible to construct actions in which the cosmological constant is bounded to be positive, which can be motivated for studying inflation. Two applications of non-linear realisations in local supersymmetry are discussed in detail. In the first one it is shown how to implement Kaehler invariance in a way that mimics the global supersymmetric case. In particular, the Kaehler-Hodge restriction on the scalar manifold, which is typical of supergravity, is avoided. In the second application the role of non-linear realisations in the construction of de Sitter vacua is discussed. Attention is devoted to the relationship with known de Sitter uplift constructions and with a new, recently proposed D-term in supergravity.Nella fisica moderna le simmetrie ricoprono un ruolo centrale e, anche nel caso in cui esso sono rotte, possono comunque porre vincoli sulle interazioni. Quando si considerano descrizioni effettive di certi modelli fisici, il gruppo di simmetria può essere infatti spontaneamente rotto ad un suo sottogruppo, ma è comunque possibile scrivere trasformazioni di simmetria che lascino l'azione invariata. Queste trasformazioni sono realizzate non linearmente sui campi, mentre nel regime senza rottura esse agiscono linearmente. Il Modello Standard della fisica delle particelle può essere interpretato come una teoria effettiva. A tal proposito, sono stati proposti scenari, detti "oltre il Modello Standard", dei quali la supersimmetria è fra i più solidi. Non essendo stata ancora rivelata direttamente negli esperimenti, la supersimmetria è postulata essere spontaneamente rotta ad una certa scala di energia maggiore del TeV. Per questa ragione è importante studiare meccanismi di rottura spontanea di supersimmetria e considerare teorie effettive a bassa energia in cui essa sia realizzata non linearmente. Un ingrediente essenziale di tale classe di modelli è la presenza nello spettro di un fermione di Goldstone a massa nulla, chiamato goldstino, associato ad ogni generatore di supersimmetria spontaneamente rotto. L'argomento di questa tesi è la costruzione e lo studio di teorie effettive in quattro dimensioni in cui la supersimmetria è spontaneamente rotta e realizzata non linearmente. Nella prima parte viene analizzato il caso di supersimmetria globale. La discussione ha inizio in supersimmetria minimale dal settore di rottura, che descrive il goldstino e le sue interazioni, ed è poi generalizzata ad un numero generico di generatori di supersimmetria spontaneamente rotti. Viene fornita in particolare una procedura sistematica per costruire teorie effettive con supersimmetria realizzata non linearmente e con qualsiasi contenuto di particelle nello spettro. Nella seconda parte della tesi, le realizzazioni non lineari sono analizzate nel caso di supersimmetria locale, ovvero supergravità. L'accoppiamento del goldstino alla gravità è presentato inizialmente e, successivamente, il meccanismo di superhiggs è discusso su un generico spazio curvo. Accoppiamenti a materia sono costruiti fornendo alcuni semplici esempi. Una nuova classe di modelli viene poi introdotta, nei quali la supersimmetria è realizzata non linearmente anche nel settore della gravità. Di conseguenza, è possibile costruire azioni nelle quali la costante cosmologica è vincolata ad essere positiva, che possono essere motivate per lo studio di modelli di inflazione. Due applicazioni delle realizzazioni non lineari in supersimmetria locale sono discusse in dettaglio. Nella prima viene mostrato come implementare l'invarianza di Kaehler in modo che essa funzioni come nel caso di supersimmetria globale. In particolare, la restrizione di tipo Kaehler-Hodge a cui la varietà degli scalari in supergravità deve essere sottoposta, è rilassata. Nella seconda applicazione viene discusso il ruolo delle realizzazioni non lineari nella costruzione di vuoti di tipo de Sitter. L'attenzione è rivolta alla relazione con modelli noti e con un nuovo tipo di D termine in supergravità, proposto recentemente.
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Grasso, Darren Trevor. "Higher order contributions to the effective action of N = 2 and 4 supersymmetric Yang-Mills theories from heat kernel techniques in superspace." University of Western Australia. School of Physics, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0179.
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The one-loop effective action for N = 2 and N = 4 supersymmetric Yang-Mills theories are computed to order F5; and F6 respectively by the use of heat kernel techniques in N = 1 superspace. The computations are carried out via the introduction of a new method for computing DeWitt-Seeley coefficients in the coincidence limit. To order F5, the bosonic components of both N = 2 and N = 4 supersymmetric Yang-Mills theories are extracted and compared with the existing literature. For N = 4 super Yang-Mills theories the F5 terms are found to be consistent with the non-Abelian Born-Infeld action computed to this order by superstring methods and various other means of computing deformations of supersymmetric Yang-Mills theory. The result proved to be the final piece of a puzzle, leaving little doubt that there exists a unique deformation of maximally symmetric super Yang-Mills theories at this order. The F6 terms will be of importance for comparison with superstring calculations, including direct tests of the AdS/CFT conjecture. The bosonic components of N = 2 supersymmetric Yang-Mills are also shown to be consistent with existing literature, and will be of importance for testing of generalizations of the AdS/CFT conjecture.
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BRAUN, GREGORY ALBERT. "HIGHER DERIVATIVE CORRECTIONS TO EXTENDED SUPERSYMMETRIC THEORIES." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1092857820.
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