Light-Cone Quantization of Electrodynamics

Light-cone quantization of (3+1)-dimensional electrodynamics is discussed, using discretization as an infrared regulator and paying careful attention to the interplay between gauge choice and boundary conditions. In the zero longitudinal momentum sector of the theory a general gauge fixing is performed and the corresponding relations that determine the constrained modes of the gauge field are obtained. The constraints are solved perturbatively and the structure of the theory is studied to lowest nontrivial order. (Talk presented at ``Theory of Hadrons and Light-Front QCD,'' Polana Zgorzelisko, Poland, August 1994.)Comment: 6 pages, LaTeX, OSU-NT-94-0

Physical Coupling Schemes and QCD Exclusive Processes

I discuss application of the BLM method to obtain commensurate scale relations connecting QCD exclusive amplitudes to other observables, in particular the heavy quark potential.Comment: 7 pages, Latex, uses l-school.sty. Talk given at "New Nonperturbative Methods and Quantization on the Light Cone," Les Houches, France, 24 Feb.-7 March 1997. To appear in the proceeding

Simple purely infinite C*-algebras and n-filling actions

Let $n$ be a positive integer. We introduce a concept, which we call the $n$-filling property, for an action of a group on a separable unital $C^*$-algebra $A$. If $A=C(\Omega)$ is a commutative unital $C^*$-algebra and the action is induced by a group of homeomorphisms of $\Omega$ then the $n$-filling property reduces to a weak version of hyperbolicity. The $n$-filling property is used to prove that certain crossed product $C^*$-algebras are purely infinite and simple. A variety of group actions on boundaries of symmetric spaces and buildings have the $n$-filling property. An explicit example is the action of $\Gamma=SL_n({\bf Z})$ on the projective $n$-space.Comment: 16 page

Neutrino Mass and Oscillations

Current evidence for neutrino oscillation is reviewed, some areas for closer investigation are suggested, and a plausible future experimental program is summarized.Comment: Text of talk presented at Lepton-Photon 99 Conference, Stanford, Aug. 9-14, 1999; to be published in the Proceedings. LaTeX, 22 pages, 4 figures, 6 Postscript file

Light-Front QCD and the Constituent Quark Model

A general strategy is described for deriving a constituent approximation to QCD, inspired by the constituent quark model and based on light-front quantization. Some technical aspects of the approach are discussed, including a mechanism for obtaining a confining potential and ways in which spontaneous chiral symmetry breaking can be manifested. (Based on a talk presented by K.G. Wilson at ``Theory of Hadrons and Light-Front QCD,'' Polana Zgorzelisko, Poland, August 1994.)Comment: 14 pages, LaTeX, no figure