ar X iv : m at h / 04 02 30 9 v 1 [ m at h . O A ] 1 9 Fe b 20 04 Minimal Dynamical Systems and Approximate Conjugacy ∗

ar X iv : h ep - t h / 04 02 14 8 v 1 1 9 Fe b 20 04 Surveillance on the light - front gauge fixing

In this work we propose two Lagrange multipliers with distinct coefficients for the light-front gauge that leads to the complete (non-reduced) propagator. This is accomplished via (n · A) 2 + (∂ · A) 2 terms in the La-grangian density. These lead to a well-defined and exact though Lorentz non invariant light front propagator.

ar X iv : a st ro - p h / 04 02 02 0 v 1 1 Fe b 20 04 Perspective from a Younger Generation – The Astro - Spectroscopy of Gisbert

ar X iv : h ep - p h / 04 02 19 0 v 1 1 8 Fe b 20 04 1 Pentaquarks in the 10 F - and 10 F - plets

ar X iv : h ep - p h / 04 02 23 9 v 1 2 3 Fe b 20 04 The η → π 0 π 0 γγ decay in Generalized χ PT

Calculations of η → ππγγ decay in Generalized chiral perturbation theory are presented. Tree level and next-to-leading corrections are involved. Sensitivity to violation of the Standard counting is discussed.

ar X iv : h ep - p h / 04 02 21 1 v 1 1 9 Fe b 20 04 The running of the electromagnetic coupling α in small - angle Bhabha scattering

A method to determine the running of α from a measurement of small-angle Bhabha scattering is proposed and worked out. The method is suited to high statistics experiments at e + e − colliders, which are equipped with luminometers in the appropriate angular region. A new simulation code predicting small-angle Bhabha scattering is also presented.