Avancerad sökning

Visar resultat 1 - 5 av 30 avhandlingar som matchar ovanstående sökkriterier.

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

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

    Sammanfattning : 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. LÄS MER

  3. 2. Twisting and Gluing : On Topological Field Theories, Sigma Models and Vertex Algebras

    Författare :Johan Källén; Maxim Zabzine; Mathias Blau; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Topological field theory; Chern-Simons theory; Contact geometry; Sigma models; Poisson vertex algebras; Vertex algebras; String theory; Theoretical Physics; Teoretisk fysik;

    Sammanfattning : This thesis consists of two parts, which can be read separately. In the first part we study aspects of topological field theories. We show how to topologically twist three-dimensional N=2 supersymmetric Chern-Simons theory using a contact structure on the underlying manifold. LÄS MER

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

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

    Sammanfattning : 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. LÄS MER

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

    Författare :Malin Göteman; Ulf Lindström; Daniel Waldram; Uppsala universitet; []
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER

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

    Författare :Jonas Persson; Ulf Lindström; Joseph Minahan; Fawad Hassan; Uppsala universitet; []
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER