Regge Asymptotics of Scattering with Flavour Exchange in QCD

The contribution to the perturbative Regge asymptotics of the exchange of two reggeized fermions with opposite helicity is investigated. The methods of conformal symmetry known for the case of gluon exchange are extended to this case where double-logarithmic contributions dominate the asymptotics. The Regge trajectories at large momentum transfer are calculated.Comment: 18 pages LATEX, 3 figures using package FEYNMAN, N3-9

Extendability of parallel sections in vector bundles

We address the following question: Given a differentiable manifold $M$ what are the open subsets $U$ of $M$ such that, for all vector bundles $E$ over $M$ and all linear connections $\nabla$ on $E$, any $\nabla$-parallel section in $E$ defined on $U$ extends to a $\nabla$-parallel section in $E$ defined on $M$? For simply connected manifolds $M$ (among others) we describe the entirety of all such sets $U$ which are, in addition, the complement of a $C^1$ submanifold (boundary allowed) of $M$; this delivers a partial positive answer to a problem posed by Antonio J. Di Scala and Gianni Manno. Furthermore, in case $M$ is an open submanifold of $\mathbb R^n$, $2 \leq n$, we prove that the complement of $U$ in $M$, not required to be a submanifold now, can have arbitrarily large $n$-dimensional Lebesgue measure.Comment: Improved presentatio

QCD at high energies and Yangian symmetry

Yangian symmetric correlators provide a tool to investigate integrability features of QCD at high energies. We discuss the kernel of the equation of perturbative Regge asymptotics, the kernels of the evolution equation of parton distributions, Born scattering amplitudes and coupling renormalization.Comment: 11 pages, contribution to ICNFP18, published versio

Railcars From Canada: A Misapplication of the Countervailing Duty Law

This Note examines the countervailing duty law and how it was applied in Railcars. Part I discusses the MTA\u27s decision to award the subway car contract to Bombardier, Inc., a Canadian corporation. The countervailing duty proceeding and other legal actions initiated in response to the allegedly subsidized contract are also described. Part II provides a general background on the Act. Part III explains the procedure for conducting a countervailing duty proceeding under the Act. After each step in a countervailing duty proceeding is outlined, its application in Railcars is discussed. Finally, Part IV analyzes how the Act was misapplied in Railcars