813 research outputs found
Perturbative Evolution and Regge Behaviour
The known analytic properties of the Compton amplitude at small place
significant constraints on its behaviour at large . This calls for a
re-evaluation of the role of perturbative evolution in past fits to data.Comment: Revised figures 4 and
Soft and hard pomerons
Regge theory provides an excellent description of small-
structure-function data from up to the highest available values. The
large- data should also be described by perturbative QCD: the two
descriptions must agree in the region where they overlap. However, at present
there is a serious lack in our understanding of how to apply perturbative QCD
at small . The usual lowest-order or next-to-lowest order expansion is not
valid, at least not until becomes much larger than is usually assumed; a
resummation is necessary, but as yet we do not know how to do this resummation.Comment: 8 pages, plain tex, with 6 figures embedded using epsf. Lecture at
Workshop on New Trends in HERA Physics, Ringberg (june 1999
Unusual high-pT jet events at HERA
We calculate the cross-section for events at HERA where the proton loses only
a minute fraction of its initial energy, all of which goes into producing a
single pair of transverse jets.Comment: 4 pages plus figure
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