Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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2006 - 20105

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Author: search.filters.author.Demir, Durmuş AliSubject: search.filters.subject.Supersymmetry

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Now showing 1 - 5 of 5
  • Master Thesis
    The Higgs Sector of the Mssm With General Soft Breaking Terms
    (Izmir Institute of Technology, 2008) Sabancı, Aslı; Demir, Durmuş Ali
    This thesis is basically established upon an analysis of determining the effects of the non-holomorphic soft supersymmetry breaking terms on the mass spectrum of the minimal supersymmetric Standard Model (MSSM). We give an overview concerning the fundamental concepts of supersymmetry (SUSY) after providing a brief discussion about the problems of Standard Model (SM) of particle physics. Then we discuss in detail that SUSY is not the exact symmetry of nature and it must be broken. In general, the breakdown of the global supersymmetry is parameterized by a set of operators. These operators could be both holomorphic or non-holomorphic in structure. Hence, in theories like the (MSSM) that do not contain any gauge singlets, these non-holomorphic supersymmetry breaking terms are soft and do not pose any problem for gauge hierarchy.In this thesis, in particular we study the impacts of the non-holomorphic softbreaking with the chargino sector so as to single out the effects of non-holomorphic trilinear couplings from the . parameters. Since the aforementioned sectors are two of the prime concerns of experiments at the LHC, we expect that our results will be testable in near future.
  • Master Thesis
    Family Non-Universal U(1)' Model
    (Izmir Institute of Technology, 2008) Hayreter, Alper; Demir, Durmuş Ali
    This thesis work is devoted to an analysis of dilepton signatures of family nonuniversal U(1)' model. We first provide a brief overview of Standard Model of particle physics and Supersymmetry then we give an introduction to basic concepts of Minimal Supersymmetric StandardModel (MSSM) and necessities to extend theMSSMwith additional symmetry groups. Later we review various existing U(1). models, then we discuss the effects and results of family non-universality in current and future colliders. The supersymmetric models extending theMSSMby an additional Abelian gauge factor U(1). in order to solve the . problem do generically suffer from anomalies disrupting the gauge coupling unification found in the MSSM. The anomalies are absent if the minimal matter content necessitated by the . problem is augmented with exotic matter species having appropriate quantum numbers. Recently, it has been shown that anomaly cancellation can also be accomplished by introducing family non-universal U(1). charges and non-holomorphic soft-breaking terms (Demir, et al. 2005) and keeping the matter content minimal without exotic particles. We discuss collider signatures of anomaly-free family non-universal U(1). model by analyzing dilepton production in future colliders. We notice that, both at LHC and NLC, one can establish existance (or absence) of such a Z. boson by simply comparing the number of dilepton production events for electron, muon and tau lepton (Hayreter 2007).
  • Master Thesis
    Renormalization Group Invariants in Minimal Supersymmetric Standard Model
    (Izmir Institute of Technology, 2006) Mutlu, Sevdiye; Demir, Durmuş Ali
    This thesis work is devoted to a detailed study of the renormalization group invariants (RG invariants) in minimal supersymmetric standard model (MSSM). The RG invariants are those Lagrangian parameters or combinations of the parameters, which exhibit no dependence on the energy scale up to the loop order with which the renormalization group equations (RGEs) are constructed. In this work, following an introductory chapter on standard model of electroweak and strong interactions as well as supersymmetry and supersymmetric field theories, we discuss construction of renormalization group equations in supersymmetric models, in particular, the minimal supersymmetric standard model with holomorphic and non-holomorphic soft terms. We finally concentrate on construction and phenomenological implications of the RG invariants in the minimal supersymmetric standard model with and without non-holomorphic supersymmetry breaking terms.
  • Master Thesis
    Flavor violation in supersymmetry
    (Izmir Institute of Technology, 2006) Çakır, Muammer Altan; Demir, Durmuş Ali
    This thesis work is meant as an introduction to supersymmetry and its phenomenological implications for the basic features of the standard model of electroweak interactions, it continues with a through denition and basic derivation of the fundamental concepts of supersymmetric eld theories, including superspace, supereld and superpotential.In a supersymmetric theory, all interactions are to be symmetric under the exchange of bosons and fermions { the superpartners. However, supersymmetry must be an explicitly yet softly broken symmetry of nature, and supersymmetry breaking parameters, the so-called soft terms, give rise to various phenomena observable at present and future experiments. The mixing among different flavors of matter-the flavor violation { is one such phenomenon which exhibits a strong dependence on the structure of the soft terms. In particular, decoupling of superpartners from the particle spectrum at a threshold energy near the ultraviolet scale of the standard model induces sizeable corrections to flavor violating interactions. These correctionsare strong enough to disqualify an otherwise viable high-scale flavor model by a confrontation with experiments at low energy. This thesis work focusses a class of flavor models, following from strings or supergravity, and provides a through analysis of their sensitivities to supersymmetric threshold corrections.
  • Master Thesis
    Higgs Bosons of Gauge-Extended Supersymmetry at the Lhc
    (Izmir Institute of Technology, 2010) Sert, Hale; Demir, Durmuş Ali
    This thesis work is devoted to a detailed phenomenological analysis of the Higgs sector of gauge-extended supersymmetry in light of the most recent experimental bounds. Such extra gauge symmetries, obtained by adding an extra Abelian symmetry U(1). to the gauge structure of the Standard Model (SM) and Minimal Supersymmetric Standard Model (MSSM) which have the same gauge structure, are urged by the . problem of the MSSM, and they also arise frequently in low-energy supersymmetric models stemming from GUTs and strings. We analyze the Higgs boson masses and their dependencies on various model parameters. In particular, we compute masses of all the Higgs bosons, and confront the mass of the lightest one with the LEP and Tevatron experiments. Then we indicate the restrictions from LEP and Tevatron bounds on the masses and remaining model parameters. We analyze correlations among various model parameters, and determine excluded regions by both scanning the parameter space and examining certain likely parameter values. Furthermore, we make educated projections for LHC measurements in light of the LEP and Tevatron restrictions on the parameter space. As a result of this thesis work we find that .-problem motivated generic lowenergy U(1). model yields lightest Higgs masses as large as . 200 GeV, and violates the Tevatron bounds for certain ranges of parameters. However, we find that U(1). model stemming from E(6) breaking elevate Higgs boson mass into Tevatron.s forbidden band when U(1). gauge coupling takes larger values than the one corresponding to one-step GUT breaking. We also obtain that the Tevatron bounds put strong restrictions on certain parameters of the U(1). model and they lead to determinations of certain parameter ranges before the LHC measurements.