Theses and Dissertations from UMD
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Item A Study of Equivalence of SUSY Theories using Adinkras and Super Virasoro Algebras(2012) Chappell, Isaac Samuel; Gates, Sylvester J; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Supersymmetry (SUSY) theories describe a wide number of quantum field theories with supersymmetric particles interacting. By using two methods, Adinkras and Super Virasoro algebras (SVAs), more information is gained about SUSY theories: (a.) when two representation may be considered equivalent, that is, describing the same physics, and (b.) the derivation of OPE's that do not rely on Wick rotations. Adinkras [1] are objects that encode important information about the theory in graphs. These graphs can be translated into matrices through what is now called a Garden Algebra. In a specfiic example, (d=4, N=4 SUSY theories,) it is found that there are six classes of SUSY theories through studying the Adinkras by one definition. However, using a criterion that is motivated by physical considerations of four dimensional field theories, this number is reduced to only three. Super Virasoro Algebras are close relatives of Super Conformal Algebras that contain a Lie algebra. They can be used to find Operator Product Expansions which are related to two-point correlation functions. By comparison of two different realizations of SVAs (the Geometrically Realization GR and the one developed by Hasiewicz, Thielemans, Troost [2],) we show that one is contained inside the other which allows some new OPEs to be calculated.Item The upside of minimal left-right supersymmetric seesaw in deflected anomaly mediation(2008-05-30) Spinner, Sogee; Mohapatra, Rabindra; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The state of the standard model of particle physics is reviewed focusing on two of it's major issues: the hierarchy problem and its inconsistency with observed neutrino masses. Supersymmetry, an elegant solution to the former, and the seesaw mechanism in left-right models, a natural solution to the latter, are then introduced. The work then focuses on a specific supersymmetric left-right models, which has an additional discrete symmetry allowing a prediction of the seesaw scale at around 1011 GeV--consistent with neutrino oscillation data. It also solves the μ problem and guarantees automatic R-parity conservation and a pair of light doubly-charged Higgses which can be searched for at the LHC. This model has interesting properties in the context of anomaly mediated supersymmetry breaking (AMSB). After a brief introduction to this topic, it is shown that this model is an instance of the Pomarol Rattazzi model of deflected AMSB. The tachyonic slepton problem of AMSB is solved in a combination of two ways: the right-handed sleptons are saved by their couplings to the low energy doubly-charged fields while the left-handed sleptons receive positive contributions from the partially decoupled D-terms. The resulting phenomenology is similar to that of mimimal AMSB due to the gaugino spectrum; however, same generation mass differences in the sfermion sector are much larger than that of mAMSB and the right-handed selectron can be as massive as the squarks. Finally, this model also contains a mechanism for solving the EWSB problem of AMSB and a dark matter candidate.Item A SUSY SO(10) GUT Model with Lopsided Structure(2007-02-27) Li, Yingchuan; Ji, Xiangdong; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The standard model (SM) of elementary particles has been established for more than 30 years and tested by a large number of experiments. However, because of the naturalness problem of the electroweak symmetry breaking scale and a large number of unexplained parameters in SM, physicists have been looking for a more fundamental theory. Supersymmetry (SUSY) and grand unification are two appealing concepts that have been mostly implemented to build candidates for beyond SM theories. SUSY helps to stabilize the scale of electroweak symmetry breaking, and grand unification embeds the SM gauge groups into larger and more fundamental gauge groups. Neutrino oscillations, signaling massive neutrinos, are the first direct evidence of beyond SM physics. A tiny neutrino mass can be elegantly explained by the seesaw mechanism. The neutrino masses from this mechanism are of Majorana type and therefore break the B-L (baryon number minus lepton number) symmetry. A favorable framework of studying neutrino masses and oscillations is the SO(10) grand unification theory (GUT) which naturally accommodates a B-L breaking. The same B-L breaking can also facilitate baryogenesis via a leptogenesis scenario. This provides an interesting correlation between these two pieces of phenomenology. This thesis presents a realistic SUSY SO(10) GUT model with lopsided structure, which generates the correct masses and mixing of neutrinos and produces the right amount of baryon asymmetry. One of the most characteristic features of this model is the lopsided mass matrices structure. We examine observables in B decays that are sensitive to this structure, and find a specific pattern of predictions that can be used to test this type of models.