Twisted Sectors and Chern-Simons Terms in M-Theory Orbifolds

It is shown that the twisted sector spectrum, as well as the associated Chern-Simons interactions, can be determined on M-theory orbifold fixed planes that do not admit gravitational anomalies. This is demonstrated for the seven-planes arising within the context of an explicit $R^6 \times S^1/Z_2 \times T^4/Z_2$ orbifold, although the results are completely general. Local anomaly cancellation in this context is shown to require fractional anomaly data that can only arise from a twisted sector on the seven-planes, thus determining the twisted spectrum up to a small ambiguity. These results open the door to the construction of arbitrary M-theory orbifolds, including those containing fixed four-planes which are of phenomenological interest.Comment: 21 pages, LaTe

An M-Theory Perspective on Heterotic K3 Orbifold Compactifications

We analyze the structure of heterotic M-theory on K3 orbifolds by presenting a comprehensive sequence of M-theoretic models constructed on the basis of local anomaly cancellation. This is facilitated by extending the technology developed in our previous papers to allow one to determine "twisted" sector states in non-prime orbifolds. These methods should naturally generalize to four-dimensional models, which are of potential phenomenological interest.Comment: 58 pages, LaTe

Filling of three-dimensional space by two-dimensional sheet growth.

Models of three-dimensional space filling based on growth of two-dimensional sheets are proposed. Beginning from planar Eden-style growth of sheets, additional growth modes are introduced. These enable the sheets to form layered or disordered structures. The growth modes can also be combined. An off-lattice kinetic Monte Carlo-based computer algorithm is presented and used to study the kinetics of the new models and the resulting structures. It is possible to study space filling by two-dimensional growth in a three-dimensional domain with arbitrarily oriented sheets; the results agree with previously published models where the sheets are only able to grow in a limited set of directions. The introduction of a bifurcation mechanism gives rise to complex disordered structures that are of interest as model structures for the mesostructure of calcium silicate hydrate in hardened cement paste.This research was supported by the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement 264448. AFR was supported by EPSRC grant EP/H035397/1.This is the author accepted manuscript. The final version is available from APS via http://dx.doi.org/10.1103/PhysRevE.92.04210

Instanton Effects in Matrix Models and String Effective Lagrangians

We perform an explicit calculation of the lowest order effects of single eigenvalue instantons on the continuous sector of the collective field theory derived from a $d=1$ bosonic matrix model. These effects consist of certain induced operators whose exact form we exhibit.Comment: Latex document, 36 pages, includes 6 figures appended as uuencoded eps files, preprint CERN-TH.7301/94, UPR-608