Message passing on the QCDSP supercomputer

The QCDSP machines were designed for lattice gauge calculations. For planning it is crucial to explore this architecture for other computationally intensive tasks. Here I describe an implementation of a simple message passing scheme. With the objective being simplicity, I introduce a small number of generic functions for manipulating a large data set spread over the machine. I test the scheme on three applications: a fast Fourier transform, arbitrary dimension SU(N) pure lattice gauge theory, and the manipulation of Fermionic Fock states through a distributed hash table. These routines compile both on QCDSP and a Unix workstation.Comment: LATTICE99(Algorithms and Machines) - 3 page

So you want to be a lattice theorist?

For this after dinner talk I intersperse images of real lattices with a discussion of the motivations for lattice gauge theory and some current unresolved issues.Comment: 6 pages, 7 figures. After dinner talk at Quark confinement and the hadron spectrum VII, Ponta Delgada, Azores, Portugal, 2-7 September 200

Cellular automata and self-organized criticality

Cellular automata provide a fascinating class of dynamical systems capable of diverse complex behavior. These include simplified models for many phenomena seen in nature. Among other things, they provide insight into self-organized criticality, wherein dissipative systems naturally drive themselves to a critical state with important phenomena occurring over a wide range of length and time scales.Comment: 23 pages, 12 figures (most in color); uses sprocl.tex; chapter submitted for "Some new directions in science on computers," G. Bhanot, S. Chen, and P. Seiden, ed

Xtoys: cellular automata on xwindows

Xtoys is a collection of xwindow programs for demonstrating simulations of various statistical models. Included are xising, for the two dimensional Ising model, xpotts, for the $q$-state Potts model, xautomalab, for a fairly general class of totalistic cellular automata, xsand, for the Bak-Tang-Wiesenfield model of self organized criticality, and xfires, a simple forest fire simulation. The programs should compile on any machine supporting xwindows.Comment: 4 pages, one figure, uuencoded compressed postscript Contribution to Lattice '95 Also available at http://penguin.phy.bnl.gov/www/papers/BNL-62123.ps.Z Programs available at http://penguin.phy.bnl.gov/www/xtoys/xtoys.htm

Minimal doubling and point splitting

Minimally-doubled chiral fermions have the unusual property of a single local field creating two fermionic species. Spreading the field over hypercubes allows construction of combinations that isolate specific modes. Combining these fields into bilinears produces meson fields of specific quantum numbers.Comment: 6 pages; poster contribution to The XXVIII International Symposium on Lattice Field Theory Revised version corrects typo