Search for dissertations about: "nonlinear sigma model"

Found 5 swedish dissertations containing the words nonlinear sigma model.

  2. 1. Anyons and antiferromagnets : two two-dimensional topics

    Author : Torbjörn Einarsson; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; antiferromagnet; two dimension; anyons; fractional statistics; Heisenberg model; torus; nonlinear sigma model; multi-component wavefuntions; spin; Néel phase; disorder; braid group;

    Abstract : .... READ MORE

  4. 2. Multi-Meson Dynamics in Chiral Perturbation Theory

    Author : Mattias Sjö; Partikel- och kärnfysik; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Spridningsamplituder; Effektiv Fältteori; Spontant symmetribrott; Ickelinjära sigmamodellen; Kirala Lagrangianer; Hadronspektroskopi; Strukturer och Interaktioner; Gitter-QCD; Scattering amplitudes; Effective Field Theories; Spontaneous Symmetry Breaking; Nonlinear sigma model; Chiral Lagrangians; Hadronic Spectroscopy; Structure and Interactions; Lattice QCD;

    Abstract : This thesis concerns scattering of light mesons in the case where the number of external particles exceeds four (that is, three or more particles in the initial or final state), calculated using chiral perturbation theory.This is both of theoretical interest in the study of scattering amplitudes, and relevant for systems of three or more pions simulated using lattice quantum chromodynamics. READ MORE

  5. 3. Superconformal D-branes and moduli spaces

    Author : Cecilia Albertsson; Eric Bergshoeff; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Physics; Fysik; Theoretical Physics; teoretisk fysik;

    Abstract : The on-going quest for a single theory that describes all the forces of nature has led to the discovery of string theory. This is the only known theory that successfully unifies gravity with the electroweak and strong forces. READ MORE

  6. 4. Criticality and Frustration: Classical and Quantum Spin Models in Two Dimensions

    Author : Per Fröjdh; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES;

    Abstract : We investigate two-dimensional spin models and begin with an introduction to critical phenomena with emphasis on classical systems with boundaries and conformal invariance. Then we introduce the antiferromagnetic quantum Heisenberg model with frustrating interactions. 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