Search for dissertations about: "string backgrounds"

Showing result 1 - 5 of 10 swedish dissertations containing the words string backgrounds.

  1. 1. String Theory at the Horizon Quantum Aspects of Black Holes and Cosmology

    University dissertation from Uppsala : Institutionen för teoretisk fysik

    Author : Martin Olsson; Ulf Danielsson; Lárus Thorlacius; [2005]
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Theoretical physics; theoretical physics; string theory; black holes; cosmology; de Sitter space; c=1 matrix models; 2D string theory; topological string theory; conifolds; 4D BPS black holes; Gödel universe; closed time-like curves; Teoretisk fysik; NATURAL SCIENCES Physics; NATURVETENSKAP Fysik;

    Abstract : String theory is a unified framework for general relativity and quantum mechanics, thus being a theory of quantum gravity. In this thesis we discuss various aspects of quantum gravity for particular systems, having in common the existence of horizons. READ MORE

  2. 2. Vacua in String Theory de Sitter Space and Stability in Flux Compactifications

    University dissertation from Uppsala : Acta Universitatis Upsaliensis

    Author : Sergio C. Vargas; Ulf Danielsson; Alessandro Tomasiello; [2018]
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; String theory; Cosmology; Flux Compactifications; Landscape; Swampland;

    Abstract : Our understanding of cosmology has evolved radically in the last decades. Current models demand the presence of dark energy in our universe and the most favored candidate behind this component is a small positive cosmological constant that characterizes a de Sitter (dS) spacetime. READ MORE

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

    University dissertation from Uppsala : Acta Universitatis Upsaliensis

    Author : Andreas Bredthauer; Ulf G. Lindström; Bengt E.W. Nilsson; [2006]
    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. 4. Strings as Sigma Models and in the Tensionless Limit

    University dissertation from Uppsala : Acta Universitatis Upsaliensis

    Author : Jonas Persson; Ulf Lindström; Joseph Minahan; Fawad Hassan; [2007]
    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

  5. 5. Strings, Branes and Non-trivial Space-times

    University dissertation from Karlstad : Karlstad University

    Author : Jonas Björnsson; Stephen Hwang; Ioannis Bakas; [2008]
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; String theory; Membranes; BRST; p -branes; p -branes; Non-compact backgrounds; WZNW-model; No-ghost theorem; Unitarity; Hermitian symmetric spaces; CFT; NATURAL SCIENCES Physics; NATURVETENSKAP Fysik; Physics; Fysik;

    Abstract : This thesis deals with different aspects of string and /p/-brane theories. One of the motivations for string theory is to unify the forces in nature and produce a quantum theory of gravity. /p/-branes and related objects arise in string theory and are related to a non-perturbative definition of the theory. READ MORE