Canonical and Functional Schrodinger Quantization of Two--Dimensional Dilaton Gravity

We discuss the relation between canonical and Schrodinger quantization of the CGHS model. We also discuss the situation when background charges are added to cancel the Virasoro anomaly. New physical states are found when the square of the background charges vanishes.Comment: 12 pages, revtex Minor correction

An Example of Poincare Symmetry with a Central Charge

We discuss a simple system which has a central charge in its Poincare algebra. We show that this system is exactly solvable after quantization and that the algebra holds without anomalies.Comment: 11 pages, Revte

Self-Duality and Maximally Helicity Violating QCD Amplitudes

I review some recent work that describes the close analogy between self-dual Yang--Mills amplitudes and QCD amplitudes with external gluons of positive helicity. This analogy is carried at tree level for amplitudes with two external quarks and up to one-loop for amplitudes involving only external gluons.Comment: 10 pages, LaTeX, no figures. Proceedings of the "Low Dimensional Field Theory Workshop, Telluride." Some ideas proposed by Duff and Isham have been include

Gauge Theoretic Formulation of Dilatonic Gravity Coupled to Particles

We discuss the formulation of the CGHS model in terms of a topological BF theory coupled to particles carrying non-Abelian charge.Comment: 4 pages. Talk given at QG99 Meeting, Sardinia, September 1999. Uses espcrc2.sty (twocolumn

Geometric Gravitational Forces on Particles Moving in a Line

In two-dimensional space-time, point particles can experience a geometric, dimension-specific gravity force, which modifies the usual geodesic equation of motion and provides a link between the cosmological constant and the vacuum $\theta$-angle. The description of such forces fits naturally into a gauge theory of gravity based on the extended Poincar\'e group, {\it i.e.\/} ``string-inspired'' dilaton gravity.Comment: 10 pages, CTP#214

Black Holes in the Gauge Theoretic Formulation of Dilatonic Gravity

We show that two-dimensional topological BF theories coupled to particles carrying non-Abelian charge admit a new coupling involving the Lagrange multiplier field. When applied to the gauge theoretic formulation of dilatonic gravity it gives rise to a source term for the gravitational field. We show that the system admits black hole solutions.Comment: Action is improved to be reparametrization invariant. Misprintings corrected. 10 pages, Late

Space-Time Noncommutativity from Particle Mechanics

We exploit the reparametrization symmetry of a relativistic free particle to impose a gauge condition which upon quantization implies space-time noncommutativity. We show that there is an algebraic map from this gauge back to the standard `commuting' gauge. Therefore the Poisson algebra, and the resulting quantum theory, are identical in the two gauges. The only difference is in the interpretation of space-time coordinates. The procedure is repeated for the case of a coupling with a constant electromagnetic field, where the reparametrization symmetry is preserved. For more arbitrary interactions, we show that standard dynamical system can be rendered noncommutative in space and time by a simple change of variables.Comment: 13 p

Poincar\'e Gauge Theory for Gravitational Forces in (1+1) Dimensions

We discuss in detail how string-inspired lineal gravity can be formulated as a gauge theory based on the centrally extended Poincar\'e group in $(1+1)$ dimensions. Matter couplings are constructed in a gauge invariant fashion, both for point particles and Fermi fields. A covariant tensor notation is developed in which gauge invariance of the formalism is manifest.Comment: 43 p., CTP#216

Temperature Expansions for Magnetic Systems

We derive finite temperature expansions for relativistic fermion systems in the presence of background magnetic fields, and with nonzero chemical potential. We use the imaginary-time formalism for the finite temperature effects, the proper-time method for the background field effects, and zeta function regularization for developing the expansions. We emphasize the essential difference between even and odd dimensions, focusing on $2+1$ and $3+1$ dimensions. We concentrate on the high temperature limit, but we also discuss the $T=0$ limit with nonzero chemical potential.Comment: 25 pages, RevTe