17,300 research outputs found
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 what
are the open subsets of such that, for all vector bundles over
and all linear connections on , any -parallel section in
defined on extends to a -parallel section in defined on
?
For simply connected manifolds (among others) we describe the entirety of
all such sets which are, in addition, the complement of a submanifold
(boundary allowed) of ; this delivers a partial positive answer to a problem
posed by Antonio J. Di Scala and Gianni Manno. Furthermore, in case is an
open submanifold of , , we prove that the complement of
in , not required to be a submanifold now, can have arbitrarily large
-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
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