Search for dissertations about: "Non-linear sigma models"

Showing result 1 - 5 of 6 swedish dissertations containing the words Non-linear sigma models.

  2. 1. Tensionless Strings and Supersymmetric Sigma Models : Aspects of the Target Space Geometry

    Author : Andreas Bredthauer; Ulf G. Lindström; Bengt E.W. Nilsson; Uppsala universitet; []
    Keywords : Theoretical physics; Theoretical Physics; String Theory; Tensionless Strings; Supergravity Backgrounds; Plane Wave; Supersymmetry; Non-linear Sigma Models; Generalized Complex Geometry; Teoretisk fysik;

    Abstract : In this thesis, two aspects of string theory are discussed, tensionless strings and supersymmetric sigma models.The equivalent to a massless particle in string theory is a tensionless string. Even almost 30 years after it was first mentioned, it is still quite poorly understood. READ MORE

  4. 2. The Complex World of Superstrings : On Semichiral Sigma Models and N=(4,4) Supersymmetry

    Author : Malin Göteman; Ulf Lindström; Daniel Waldram; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Non-linear sigma models; extended supersymmetry; semichiral superfields; neutral hyperkähler geometry; generalized Kähler geometry; T-duality; vector multiplets; Theoretical Physics; Teoretisk fysik;

    Abstract : Non-linear sigma models with extended supersymmetry have constrained target space geometries, and can serve as effective tools for investigating and constructing new geometries. Analyzing the geometrical and topological properties of sigma models is necessary to understand the underlying structures of string theory. READ MORE

  5. 3. Strings as Sigma Models and in the Tensionless Limit

    Author : Jonas Persson; Ulf Lindström; Joseph Minahan; Fawad Hassan; Uppsala universitet; []
    Keywords : Theoretical physics; Theoretical Physics; String Theory; Tensionless Strings; Supergravity Backgrounds; Plane Wave; Extended Supersymmetry; Non-Linear Sigma Models; Generalized Complex Geometry; T-duality; Teoretisk fysik;

    Abstract : This thesis considers two different aspects of string theory, the tensionless limit of the string and supersymmetric sigma models with extended supersymmetry. First, the tensionless limit is used to find a IIB supergravity background generated by a tensionless string. The background has the characteristics of a gravitational shock-wave. READ MORE

  6. 4. Going Round in Circles : From Sigma Models to Vertex Algebras and Back

    Author : Joel Ekstrand; Maxim Zabzine; Anton Alekseev; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Chiral de Rham complex; Conformal field theory; Poisson vertex algebra; Sigma model; String theory; Vertex algebra; Theoretical Physics; Teoretisk fysik;

    Abstract : In this thesis, we investigate sigma models and algebraic structures emerging from a Hamiltonian description of their dynamics, both in a classical and in a quantum setup. More specifically, we derive the phase space structures together with the Hamiltonians for the bosonic two-dimensional non-linear sigma model, and also for the N=1 and N=2 supersymmetric models. READ MORE

  7. 5. Factors Shaping Process and Representation in Multiple-Cue Judgment

    Author : Anna-Carin Olsson; Peter Juslin; Nigel Harvey; Umeå universitet; []
    Keywords : SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Psychology; Multiple-Cue Judgment; categorization; cognitive processes; knowl-edge representations; exemplar-based models; cue abstraction models; Psykologi; Psychology; Psykologi; Psychology; psykologi;

    Abstract : This thesis investigates the cognitive processes and representations underlying human judgment in a multiple-cue judgment task. Several recent models as-sume that people have several qualitatively distinct and competing levels of knowledge representations (Ashby, Alfonso-Reese, Turken, & Waldron, 1998; Erickson & Kruschke, 1998; Nosofsky, Palmeri, & McKinley, 1994; Sloman, 1996). READ MORE