Sökning: "instantons"

Visar resultat 6 - 10 av 11 avhandlingar innehållade ordet instantons.

  1. 6. Pair production, vacuum birefringence and radiation reaction in strong field QED

    Författare :Greger Torgrimsson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; worldline instantons; lightfront quantisation; radiation reaction; vacuum birefringence; nonperturbative pair production;

    Sammanfattning : In this thesis we consider three QED phenomena in strong electromagnetic fields: Schwinger pair production, vacuum birefringence and radiation reaction. We study electron-positron pair production in a variety of field configurations and, using complex worldline instantons, reveal new insights into the case of fields with lightlike inhomogeneities. LÄS MER

  3. 7. Localization, supersymmetric gauge theories and toric geometry

    Författare :Jacob Winding; Maxim Zabzine; Sara Pasquetti; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Supersymmetry; gauge theory; localization; toric geometry; Theoretical Physics; Teoretisk fysik;

    Sammanfattning : Gauge theories is one of the most pervasive and important subject of modern theoretical physics, and there are still many things about them we do not understand. In particular dealing with strongly coupled theories where normal perturbative techniques do not apply is a fundamental open problem. LÄS MER

  4. 8. Localization of N=2 Field Theories: a Twisted Path Across Four Manifolds

    Författare :Lorenzo Ruggeri; Guido Festuccia; Stefano Cremonesi; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Supersymmmetry; gauge theories; localization;

    Sammanfattning : Supersymmetric quantum field theories provide a framework where certain physical observables can be computed exactly. In those cases, one not only has control over perturbative contributions but also over non-perturbative contributions. LÄS MER

  5. 9. Pierced, Wrapped and Torn : Aspects of String Theory Compactifications

    Författare :Magdalena Larfors; Ulf Danielsson; Gary Shiu; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mathematical physics; Matematisk fysik; Theoretical Physics; teoretisk fysik;

    Sammanfattning : An outstanding problem in physics is to find a unified framework for quantum mechanics and general relativity. This is required for a better understanding of black holes and the early cosmology of the universe. String theory provides such a unification. In this thesis, we study aspects of compactifications of type IIB string theory. LÄS MER

  7. 10. 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