The objective of this thesis is to derive a supersymmetric Lagrangian for fermionic fields with mass dimension one and to discuss their coupling to the O'Raifeartaigh model which is the simplest model permitting supersymmetry breaking. In addition it will be shown that eigenspinors of the charge conjugation operator (ELKO) exhibit a different transformation behaviour under discrete symmetries than previously assumed.<p> The calculations confirm that ELKO spinors are not eigenspinors of the parity operator and satisfy (<i>CPT</i>)² = - 1 which identifies them as representation of a nonstandard Wigner class. However, it is found that ELKO spinors transform symmetrically under parity instead of the previously assumed asymmetry. Furthermore, it is demonstrated that ELKO spinors transform asymmetrically under time reversal which is opposite to the previously reported symmetric behaviour. These changes affect the (anti)commutation relations that are satisfied by the operators acting on ELKO spinors. Therefore, ELKO spinors satisfy the same (anti)commutation relations as Dirac spinors, even though they belong to two different representations of the Lorentz group.<p> Afterwards, a supersymmetric model for fermionic fields with mass dimension one based on a general superfield with one spinor index is formulated. It includes the systematic derivation of all associated chiral and anti-chiral superfields up to third order in covariant derivatives. Starting from these fundamental superfields a supersymmetric on-shell Lagrangian that contains a kinetic term for the fermionic fields with mass dimension one is constructed. This on-shell Lagrangian is subsequently used to derive the on-shell supercurrent and to successfully formulate a consistent second quantisation for the component fields. In addition, the Hamiltonian in position space that corresponds to the supersymmetric Lagrangian is calculated. As the Lagrangian is by construction supersymmetric and the second quantisation of the component fields is consistent with their general supertranslations, the Hamiltonian is positive definite. This is confirmed by the results for the Hamiltonian in momentum space and the derivation of the creation and annihilation operators in momentum space. Based on these results, fermionic fields with mass dimension one represent an intriguing candidate for supersymmetric dark matter.<p> As an application the coupling of the fermionic fields with mass dimension one to the O'Raifeartaigh model is discussed. It turns out that the coupled model has two distinct solutions. The first solution representing a local minimum of the superpotential spontaneously breaks supersymmetry in perfect analogy to the O'Raifeartaigh model. The second solution is more intriguing as it corresponds to a global minimum of the superpotential. In this case the coupling to the fermionic sector restores supersymmetry. This is, however, achieved at the cost of breaking Lorentz invariance. Finally, the mass matrices for the multiplets of the coupled model are presented. It turns out that it contains two bosonic triplets and one fermionic doublet which are mass multiplets. In addition it contains a massless fermionic doublet as well as one fermionic triplet which is not a mass multiplet but rather an interaction multiplet that contains component fields of different mass dimension.<p> These results show that the presented model for fermionic fields with mass dimension one is a viable candidate for supersymmetric dark matter that could be accessible to experiments in the near future.

Different aspects of specific models in supersymmetry as well as constraints on decaying dark matter are analysed in this thesis. In chapter 1 we give a general introduction to supersymmetry, and briefly discuss some of the concepts that are used throughout the thesis. In chapter 2 we present a version of Gauge Mediated Supersymmetry Breaking which preserves an $R$-symmetry---the gauginos are Dirac particles, the $A$-terms are zero, and there are four Higgs doublets. This offers an alternative way for gauginos to acquire mass in the supersymmetry-breaking models of Intriligator, Seiberg, and Shih \cite{Intriligator:2006dd} . Additionally, we investigate the possibility of using $R$-symmetric gauge mediation to realise the spectrum and large sfermion mixing of the model of Kribs, Poppitz, and Weiner \cite{Kribs:2007ac}. In chapter 3 we investigate the Higgs sector of the $R$-symmetric model presented in chapter 2. Furthermore, a scan of the parameter space and sample spectra are provided. Other attributes like the tuning of the model are discussed. In chapter 4 we present a complete analysis of the cosmological constraints on decaying dark matter. In order to do this, we have updated and extended previous analyses to include Lyman-$\alpha$ forest, large scale structure, and weak lensing observations. Astrophysical constraints are not considered in this thesis. The bounds on the lifetime of decaying dark matter are dominated by either the late-time integrated Sachs-Wolfe effect for the scenario with weak reionization, or CMB polarisation observations when there is significant reionization. For the respective scenarios, the lifetimes for decaying dark matter are $\Gamma^{-1} \gtrsim 100$ Gyr and $ (f \Gamma) ^{-1} \gtrsim 5.3 \times 10^8$ Gyr (at 95.4\% confidence level), where the phenomenological parameter $f$ is the fraction of the decay energy deposited in baryonic gas. This allows us to constrain particle physics models with dark matter candidates through investigation of dark matter decays into Standard Model particles via effective operators. For decaying dark matter of $\sim 100$ GeV mass, we found that the size of the coupling constant in the effective dimension-4 operators responsible for dark matter decay has to generically be $ \lesssim 10^{-22}$.

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 compacti&#64257;cación 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 compacti&#64257;cado 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 &#64257;jos 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. Gersdor&#64256;. 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&#8722;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 modi&#64257;caciones 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. Gersdor&#64256;.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 con&#64257;guración 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 cap&#305;tulo 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 &#64257;eld theories, corresponding to chapter 2, and the process of compacti&#64257;cation 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 &#64257;ve dimensional space time compacti&#64257;ed 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. Gersdor&#64256;. 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 &#64257;fth coordinate is of size of few TeV&#8722;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 veri&#64257;ed in chapter 7, with a slight modi&#64257;cation in the model. These model was entirely developed within what is called real formalism which consists in doubling the o&#64256;-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 super&#64257;eld 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 super&#64257;elds showing the equivalence between the two formalisms. This is a work to be submitted. In chapter 7 we generalize the previous model within super&#64257;eld 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 di&#64256;erent from the one appearing in chapter 5 and the EWSB is induced by radiative corrections with a tiny &#64257;ne 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. Gersdor&#64256;. 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 &#64257;ve dimensional bulk with bulk mass M and arbitrary mass-like boundary terms. We &#64257;nd 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 con&#64257;guration 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.

Conventional searches for the charged Higgs boson using its production in association with Standard Model (SM) quarks is notoriously weak in the mid-tanB range. Hoping to find an alternate channel to fill this gap, the production of the charged Higgs boson in association with supersymmetric squarks is studied. Using Monte Carlo generators the production at the LHC is simulated within the non universal Higgs mass model (NUHM). If the six parameters of the model (m0, m1/2, A0, tanB, u, mA) induce small masses of the stop, sbottom and charged Higgs, the production cross section can be of the order pb. Through scans of the input parameter the cross section is maximized, with the requirement that the stop decays directly to a neutralino - simplifying detection, in the point (m0, m1/2, A0, tanB, u, mA) = (190, 187, -1147, 179, 745, 13.2) where the cross section is 559 fb. The production is compared to the irreducible backgrounds stop, stop, t, tbar and t, tbar + 2 jets. The former poses no severe constraints and can be easily removed using appropriate cuts. The latter, SM background, has a cross section almost 1000 times larger and strong cuts must be imposed to suppress it. Neglecting hadronization and systematic effects, we show that a 5 sigma discovery is possible at 133 fb-1. In this range, mH+ = 194 GeV and tanB = 13.2, other channels have little or no prospects of detecting the charged Higgs and the studied process shows good prospects for complementing charged Higgs searches at the LHC in the mid-tanB range.

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Physics and Astronomy." Includes bibliographical references (p. 173-185).

Thesis (Ph. D.)--University of Chicago, Dept. of Physics, December 2003. / Includes bibliographical references. Also available on the Internet.

No description available.

We explore supersymmetric quantum field theories in three and four dimensions via an analysis of their BPS spectrum. In four dimensions, we develop the theory of BPS quivers which provides a simple picture of BPS states in terms of a set of building block atomic particles, and basic quantum mechanical interactions. We develop efficient techniques, rooted in an understanding of quantum-mechanical dualities, for determining the spectrum of bound states, and apply these techniques to calculate the spectrum in a wide class of field theories including ADE gauge theories with matter, and Argyres-Douglas type theories. Next, we explore the geometric content of quivers in the case when the four-dimensional field theory can be constructed from the six-dimensional (2; 0) superconformal field theory compactified on a Riemann surface. We find that the quiver and its superpotential are determined by an ideal triangulation of the associated Riemann surface. The significance of this triangulation is that it encodes the data of geodesics on the surface which in turn are the geometric realization of supersymmetric particles. Finally we describe a class of three-dimensional theories which are realized as supersymmetric domain walls in the previously studied four-dimensional theories. This leads to an understanding of quantum field theories constructed from the six-dimensional (2; 0) superconformal field theory compactified on a three-manifold, and we develop the associated geometric dictionary. We find that the structure of the field theory is determined by a decomposition of the three-manifold into tetrahedra and a braid which species the relationship between ultraviolet and infrared geometries. The phenomenon of BPS wall-crossing in four dimensions is then seen in these domain walls to be responsible for three-dimensional mirror symmetries. / Physics

No description available.

No description available.