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The Complex World o...
The Complex World of Superstrings : On Semichiral Sigma Models and N=(4,4) Supersymmetry
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- Göteman, Malin (författare)
- Uppsala universitet,Teoretisk fysik
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- Lindström, Ulf, Prof. (preses)
- Uppsala universitet,Teoretisk fysik
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- Waldram, Daniel, Prof. (opponent)
- Imperial College London
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(creator_code:org_t)
- ISBN 9789155485191
- Uppsala : Acta Universitatis Upsaliensis, 2012
- Engelska 131 s.
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Serie: Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 ; 989
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Abstract
Ämnesord
Stäng
- 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.The most general two-dimensional sigma model with manifest N=(2,2) supersymmetry can be parametrized by chiral, twisted chiral and semichiral superfields. In the research presented in this thesis, N=(4,4) (twisted) supersymmetry is constructed for a semichiral sigma model. It is found that the model can only have additional supersymmetry off-shell if the target space has a dimension larger than four. For four-dimensional target manifolds, supersymmetry can be introduced on-shell, leading to a hyperkähler manifold, or pseudo-supersymmetry can be imposed off-shell, implying a target space which is neutral hyperkähler.Different sigma models and corresponding geometries can be related to each other by T-duality, obtained by gauging isometries of the Lagrangian. The semichiral vector multiplet and the large vector multiplet are needed for gauging isometries mixing semichiral superfields, and chiral and twisted chiral superfields, respectively. We find transformations that close off-shell to a N=(4,4) supersymmetry on the field strengths and gauge potentials of the semichiral vector multiplet, and show that this is not possible for the large vector multiplet.A sigma model parametrized by chiral and twisted chiral superfields can be related to a semichiral sigma model by T-duality. The N=(4,4) supersymmetry transformations of the former model are linear and close off-shell, whereas those of the latter are non-linear and close only on-shell. We show that this discrepancy can be understood from T-duality, and find the origin of the non-linear terms in the transformations.
Ämnesord
- NATURVETENSKAP -- Fysik -- Annan fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Other Physics Topics (hsv//eng)
Nyckelord
- Non-linear sigma models
- extended supersymmetry
- semichiral superfields
- (neutral) hyperkähler geometry
- generalized Kähler geometry
- T-duality
- vector multiplets
- Theoretical Physics
- Teoretisk fysik
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- dok (ämneskategori)
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