ar X iv : h ep - t h / 94 12 13 6 v 1 1 5 D ec 1 99 4 Relativistically Covariant Symmetry in QED

ar X iv : h ep - t h / 94 12 15 6 v 1 1 8 D ec 1 99 4 Quantal Overlapping Resonance Criterion : the Pullen Edmonds Model

ar X iv : h ep - t h / 92 11 12 4 v 1 2 6 N ov 1 99 2 Chiral Symmetry Breaking with the Curtis - Pennington Vertex

We study chiral symmetry breaking in quenched QED 4 , using a vertex Ansatz recently proposed by Curtis and Pennington. Bifurcation analysis is employed to establish the existence of a critical coupling and to estimate its value. The main results are in qualitative agreement with the ladder approximation, the numerical changes being minor.

ar X iv : h ep - t h / 98 12 13 2 v 1 1 5 D ec 1 99 8 Lorentz and PCT Violating Chern - Simons Term in the Derivative Expansion of QED ∗

We calculate by the method of dimensional regularization and derivative expansion the one-loop effective action for a Dirac fermion with a Lorentz-violating and PCT-odd kinetic term in the background of a gauge field. We show that this term induces a Chern-Simons modification to Maxwell theory. Some related issues are also discussed.

ar X iv : h ep - t h / 05 12 13 4 v 1 1 3 D ec 2 00 5 A LORENTZ COVARIANT NONCOMMUTATIVE GEOMETRY

A noncommutative geometry that preserves lorentz covariance was introduced by Hartland Snyder in 1947. We show that this geometry has unusual properties under momentum translation, and derive for it a form of star product.

ar X iv : h ep - t h / 94 12 09 9 v 1 1 2 D ec 1 99 4 Poisson Poincaré groups

We present almost complete list of normal forms of classical r-matrices on the Poincaré group.