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SL(2,Z) tensionless string backgrounds in IIB string theory
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Theoretical Physics.
2003 (English)In: Classical and Quantum Gravity, ISSN 0264-9381, Vol. 20, 3081–3086- p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2003. Vol. 20, 3081–3086- p.
National Category
Physical Sciences
URN: urn:nbn:se:uu:diva-95667OAI: oai:DiVA.org:uu-95667DiVA: diva2:169974
Available from: 2007-04-03 Created: 2007-04-03 Last updated: 2012-05-18Bibliographically approved
In thesis
1. Strings as Sigma Models and in the Tensionless Limit
Open this publication in new window or tab >>Strings as Sigma Models and in the Tensionless Limit
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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. Then, the quantization of the tensionless string in a pp-wave background is performed and the result is found to agree with what is obtained by taking a tensionless limit directly in the quantized theory of the tensile string. Hence, in the pp-wave background the tensionless limit commutes with quantization. Next, supersymmetric sigma models and the relation between extended world-sheet supersymmetry and target space geometry is studied. The sigma model with N=(2,2) extended supersymmetry is considered and the requirement on the target space to have a bi-Hermitean geometry is reviewed. The Hamiltonian formulation of the model is constructed and the target space is shown to have generalized Kähler geometry. The equivalence between bi-Hermitean geometry and generalized Kähler follows, in this context, from the equivalence between the Lagrangian- and Hamiltonian formulation of the sigma model. Then, T-duality in the Hamiltonian formulation of the sigma model is studied and the explicit T-duality transformation is constructed. It is shown that the transformation is a symplectomorphism, i.e. a generalization of a canonical transformation. Under certain assumptions, the amount of extended supersymmetry present in the sigma model is shown to be preserved under the T-duality transformation. Next, extended supersymmetry in a first order formulation of the sigma model is studied. By requiring N=(2,2) extended world-sheet supersymmetry an intriguing geometrical structure arises and in a special case generalized complex geometry is found to be contained in the new framework.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. viii+127 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 286
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
urn:nbn:se:uu:diva-7783 (URN)978-91-554-6848-4 (ISBN)
Public defence
2007-04-27, Häggsalen, Ångström Laboratory, Lägerhyddsvägen 1, Uppsala, 13:15
Available from: 2007-04-03 Created: 2007-04-03 Last updated: 2011-06-21Bibliographically approved

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