Prof Andre Lukas

Abstract:

We study four-dimensional low energy effective actions for conifold transitions of Calabi-Yau spaces in the context of IIB supergravity. The actions are constructed by examining the mass of D3-branes wrapped on collapsing/expanding three-cycles. We then study the cosmology of the conifold transition, including consequences for moduli stabilization, taking into account the effect of the additional states which become light at the transition. We find, the degree to which the additional states are excited is essential for whether the transition is dynamically realized. © 2005 The American Physical Society.

Abstract:

Compact manifolds of G2 holonomy may be constructed by dividing a seven-torus by some discrete symmetry group and then blowing up the singularities of the resulting orbifold. We classify possible group elements that may be used in this construction and use this classification to find a set of possible orbifold groups. We then derive the moduli Kähler potential for M-theory on the resulting class of G2 manifolds with blown-up codimension four singularities. © 2005 The American Physical Society.

Abstract:

M theory is considered in its low-energy limit on a G2 manifold with nonvanishing flux. Using the Killing spinor equations for linear flux, an explicit set of first-order bosonic equations for supersymmetric solutions is found. These solutions describe a warped product of a domain wall in four-dimensional space-time and a deformed G2 manifold. It is shown how these domain walls arise from the perspective of the associated four-dimensional N = 1 effective supergravity theories. We also discuss the inclusion of membrane and M5-brane sources. © 2005 The American Physical Society.

Abstract:

Compact manifolds of G2 holonomy may be constructed by dividing a seven-torus by some discrete symmetry group and then blowing up the singularities of the resulting orbifold. We classify possible group elements that may be used in this construction and use this classification to find a set of possible orbifold groups. We then derive the moduli Kähler potential for M-theory on the resulting class of G2 manifolds with blown-up codimension four singularities. © 2005 The American Physical Society.