Particle theory

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:

This talk discusses the relative impact of running-coupling and other higher-order corrections on the small-x gluon-gluon splitting function. Comments are made on similarities with some aspects of the Balitsky-Kovchegov equation, which arise because of the presence of an effective infrared cutoff in both cases. It is emphasised that, at least in the splitting-function case, the asymptotic small-x behaviour has little relevance to the phenomenologically interesting preasymptotic region. This is illustrated with the aid of a convolution of the resummed splitting function with a toy gluon distribution.