| 1. |
- Bao, Ling, 1980, et al.
(författare)
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A note on topological M5-branes and string-fivebrane duality
- 2008
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 2008:6, s. 11-
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Tidskriftsartikel (refereegranskat)abstract
- We derive the stability conditions for the M5-brane in topological M-theory using k-symmetry. The non-linearly self-dual 3-form on the world-volume is necessarily non-vanishing, as is the case also for the 2-form field strengths on coisotropic branes in topological string theory. It is demonstrated that the self-duality is consistent with the stability conditions, which are solved locally in terms of a tensor in the representation 6 of SU(3) subset of G(2). The double dimensional reduction of the M5-brane is the D4-brane, and its direct reduction is an NS5-brane. We show that the equation of motion for the 3-form on the NS5-brane wrapping a Calabi-Yau space is exactly the Kodaira-Spencer equation, providing support for a string-fivebrane duality in topological string theory.
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| 2. |
- Bao, Ling, 1980, et al.
(författare)
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A Note on Topological M5-branes and String-Fivebrane Duality
- 2006
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We derive the stability conditions for the M5-brane in topological M-theory using kappa-symmetry. The non-linearly self-dual 3-form on the world-volume is necessarily non-vanishing, as is the case also for the 2-form field strengths on coisotropic branes in topological string theory. It is demonstrated that the self-duality is consistent with the stability conditions, which are solved locally in terms of a tensor in the representation 6 of SU(3) in G_2. The double dimensional reduction of the M5-brane is the D4-brane, and its direct reduction is an NS5-brane. We show that the equation of motion for the 3-form on the NS5-brane wrapping a Calabi-Yau space is exactly the Kodaira-Spencer equation, providing support for a string-fivebrane duality in topological string theory.
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| 3. |
- Bao, Ling, 1980, et al.
(författare)
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Aspects of higher curvature terms and U-duality
- 2007
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Ingår i: Classical and Quantum Gravity. - : IOP Publishing. - 0264-9381 .- 1361-6382. ; 25:9
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Tidskriftsartikel (refereegranskat)abstract
- We discuss various aspects of dimensional reduction of gravity with theEinstein-Hilbert action supplemented by a lowest order deformation formed asthe Riemann tensor raised to powers two, three or four. In the case of R^2 wegive an explicit expression, and discuss the possibility of extended cosetsymmetries, especially SL(n+1,Z) for reduction on an n-torus to threedimensions. Then we start an investigation of the dimensional reduction of R^3and R^4 by calculating some terms relevant for the coset formulation, aiming inparticular towards E_8(8)/(Spin(16)/Z_2) in three dimensions and aninvestigation of the derivative structure. We emphasise some issues concerningthe need for the introduction of non-scalar automorphic forms in order torealise certain expected enhanced symmetries.
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| 4. |
- Bao, Ling, 1980, et al.
(författare)
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Membranes for Topological M-Theory
- 2005
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Ingår i: Journal of High Energy Physics.
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Tidskriftsartikel (refereegranskat)abstract
- We formulate a theory of topological membranes on manifolds with G_2 holonomy. The BRST charges of the theories are the superspace Killing vectors (the generators of global supersymmetry) on the background with reduced holonomy G_2. In the absence of spinning formulations of supermembranes, the starting point is an N=2 target space supersymmetric membrane in seven euclidean dimensions. The reduction of the holonomy group implies a twisting of the rotations in the tangent bundle of the branes with ``R-symmetry'' rotations in the normal bundle, in contrast to the ordinary spinning formulation of topological strings, where twisting is performed with internal U(1) currents of the N=(2,2) superconformal algebra. The double dimensional reduction on a circle of the topological membrane gives the strings of the topological A-model (a by-product of this reduction is a Green-Schwarz formulation of topological strings). We conclude that the action is BRST-exact modulo topological terms and fermionic equations of motion. We discuss the role of topological membranes in topological M-theory and the relation of our work to recent work by Hitchin and by Dijkgraaf et al.
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| 5. |
- Bao, Ling, 1980, et al.
(författare)
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U-Duality and the Compactified Gauss-Bonnet Term
- 2007
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Ingår i: Journal of High Energy Physics.
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Tidskriftsartikel (refereegranskat)abstract
- We present the complete toroidal compactification of the Gauss-Bonnet Lagrangian from D dimensions to D-n dimensions. Our goal is to investigate the resulting action from the point of view of the "U-duality" symmetry SL(n+1,R) which is present in the tree-level Lagrangian when D-n=3. The analysis builds upon and extends the investigation of the paper [arXiv:0706.1183], by computing in detail the full structure of the compactified Gauss-Bonnet term, including the contribution from the dilaton exponents. We analyze these exponents using the representation theory of the Lie algebra sl(n+1,R) and determine which representation is the relevant one for quadratic curvature corrections. By interpreting the result of the compactification as a leading term in a large volume expansion of an SL(n+1,Z)-invariant action, we conclude that the overall exponential dilaton factor should not be included in the representation structure. As a consequence, all dilaton exponents correspond to weights of sl(n+1,R), which, nevertheless, remain on the positive side of the root lattice.
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| 6. |
- Bengtsson, Viktor, 1981, et al.
(författare)
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The B-model on the A-model NS5-brane
- 2008
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Ingår i: arXiv.org/abs/0805.1782.
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Tidskriftsartikel (refereegranskat)abstract
- We formulate the dynamics for the NS5-brane of the A-model, via the 'maximal form' method, which couples all background fields to the world-volume. This procedure provides the extra one- and five-forms fields of the extended Hitchin model. The generalised B-model emerges as the world-volume theory of this brane. The starting point of the construction is an embedding of the brane in a superspace geometry with 16 fermionic directions. The correspondence with Hitchin's formulation in terms of pure spinors is explained.
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| 7. |
- Cederwall, Martin, 1961, et al.
(författare)
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An introduction to analytical mechanics
- 2009
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- The present edition of this compendium is intended to be a complement to the textbook “Engineering Mechanics” by J.L. Meriam and L.G. Kraige (MK) for the course ”Mekanik F del 2” given in the first year of the Engineering physics (Teknisk fysik) programme at Chalmers University of Technology, Gothenburg. Apart from what is contained in MK, this course also encompasses an elementary understanding of analytical mechanics, especially the Lagrangian formulation. In order not to be too narrow, this text contains not only what is taught in the course, but tries to give a somewhat more general overview of the subject of analytical mechanics. The intention is that an interested student should be able to read additional material that may be useful in more advanced courses or simply interesting by itself. The chapter on the Hamiltonian formulation is strongly recommended for the student who wants a deeper theoretical understanding of the sub ject and is very relevant for the connection between classical mechanics (”classical” here denoting both Newton’s and Einstein’s theories) and quantum mechanics. The mathematical rigour is kept at a minimum, hopefully for the benefit of physical understanding and clarity. Notation is not always consistent with MK; in the cases it differs our notation mostly conforms with generally accepted conventions. The text is organised as follows: In Chapter 1 a background is given. Chapters 2, 3 and 4 contain the general setup needed for the Lagrangian formalism. In Chapter 5 Lagrange’s equation are derived and Chapter 6 gives their interpretation in terms of an action. Chapters 7 and 8 contain further developments of analytical mechanics, namely the Hamiltonian formulation and a Lagrangian treatment of constrained systems. Exercises are given at the end of each chapter. Finally, a translation table from English to Swedish of some terms used is found. Many of the exercise problems are borrowed from material by Ture Eriksson, Arne Kihlberg and Göran Niklasson. The selection of exercises has been focused on Chapter 5, which is of greatest use for practical applications.
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| 8. |
- Cederwall, Martin, 1961
(författare)
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Ljuskonen
- 2005
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Ingår i: Fysikaktuellt 1 (2005) 20.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Logotypen för Fysikåret 2005 innehåller en bild av en kon. Varför, och vad betyder den? Samtidigt som dess timglasform kan tänkas alludera på tidens gång, både den fysikaliska tiden och de 100 åren av fysik sedan Einsteins upptäckter 1905, är den primärt en illustration av en av de viktigaste egenskaperna hos rumtiden såsom den beskrivs i Einsteins speciella relativitetsteori. Hur läser man denna bild av rumtiden?
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| 9. |
- Cederwall, Martin, 1961
(författare)
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M-branes on U-folds
- 2007
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Ingår i: Proceedings of the 7th International Workshop "Supersymmetries and Quantum Symmetries", Dubna, July 30-August 4, 2007. ; , s. 8-
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Konferensbidrag (refereegranskat)abstract
- We give a preliminary discussion of howthe addition of extra coordinates in M-theory, which together with theoriginal ones parametrise a U-fold, can serve as a tool forformulating brane dynamics with manifest U-duality. The redundantdegrees of freedom are removed by generalised self-duality constraintsor calibration conditions made possible by the algebraic structure ofU-duality.
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| 10. |
- Cederwall, Martin, 1961
(författare)
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N=8 superfield formulation of the Bagger-Lambert-Gustavsson model
- 2008
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Ingår i: Journal of High Energy Physics.
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Tidskriftsartikel (refereegranskat)abstract
- We reformulate the Bagger-Lambert-Gustavsson model using an N=8 superspace, thus making the full supersymmetry manifest. The formulation is based on appropriate "pure spinor wave functions" for the Chern-Simons and matter multiplets. The Lagrangian has an extremely simple structure, essentially containing a Chern-Simons-like term for the gauge field wave function and a minimally coupled matter wave function. No higher order interactions than cubic are present. The consistency of the setup relies on an interplay between the algebraic structures of the 3-algebra and of the pure spinors.
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