Past String Theory Seminar

21 January 2004
12:00
Abstract
After a review of the symmetries of supergravity theories and Kac-Moody algebras, we explain show that M theory is likely to possess a very large Kac-Moody symmetry of rank eleven, denoted by E_{11}. We also provide evidence that even pure gravity and the closed bosonic string possess analogous Kac-Moody symmetries. Finally, we explain how the central charges of the maximal supergravity theories arise naturally in E_{11}.
  • String Theory Seminar
3 December 2003
12:00
Kellogg Stelle
Abstract
At the leading order, the low-energy effective field equations in string theory admit solutions of the form of products of Minkowski spacetime and a Ricci-flat Calabi-Yau space. The equations of motion receive corrections at higher orders in \alpha', which imply that the Ricci-flat Calabi-Yau space is modified. In an appropriate choice of scheme, the Calabi-Yau space remains Kahler, but is no longer Ricci-flat. We discuss the nature of these corrections at order {\alpha'}^3, and consider the deformations of all the known cohomogeneity one non-compact Kahler metrics in six and eight dimensions. We do this by deriving the first-order equations associated with the modified Killing-spinor conditions, and we thereby obtain the modified supersymmetric solutions. We also give a detailed discussion of the boundary terms for the Euler complex in six and eight dimensions, and apply the results to all the cohomogeneity one examples. Additional material will be presented concerning the case of holonomy G_2.
  • String Theory Seminar
17 November 2003
12:00
Sanjaye Ramgoolam
Abstract
I discuss gauge theories for commutative but non-associative algebras related to the SO(2k+1) covariant finite dimensional fuzzy 2k-sphere algebras. A consequence of non-associativity is that gauge fields and gauge parameters have to be generalized to be functions of coordinates as well as derivatives. The usual gauge fields depending on coordinates only are recovered after a partial gauge fixing.The deformation parameter for these commutative but non-associative algebras is a scalar of the rotation group. This suggests interesting string-inspired algebraic deformations of spacetime which preserve Lorentz-invariance. The talk will be based on hepth/0310153
  • String Theory Seminar

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