10,382 research outputs found
Photon Structure, as seen at HERA
At HERA, the electron-proton collider at DESY, Hamburg, the large flux of
almost on-shell photons accompanying the lepton beam is being used to shed new
light on the structure of the photon. Recent results are reviewed and
discussed, with emphasis on those aspects of the photon's nature which should
be understandable using perturbative QCD.Comment: 20 pages, latex, 10 figures appended as uuencoded file. Full
postscript version including figures available at
http://zow00.desy.de:8000/~butterwo/pubs.html#ke
The CEDAR Project
We describe the plans and objectives of the CEDAR project (Combined e-Science
Data Analysis Resource for High Energy Physics) newly funded by the PPARC
e-Science programme in the UK. CEDAR will combine the strengths of the well
established and widely used HEPDATA database of HEP data and the innovative
JetWeb data/Monte Carlo comparison facility, built on the HZTOOL package, and
will exploit developing grid technology. The current status and future plans of
both of these individual sub-projects within the CEDAR framework are described,
showing how they will cohesively provide (a) an extensive archive of Reaction
Data, (b) validation and tuning of Monte Carlo programs against these reaction
data sets, and (c) a validated code repository for a wide range of HEP code
such as parton distribution functions and other calculation codes used by
particle physicists. Once established it is envisaged CEDAR will become an
important Grid tool used by LHC experimentalists in their analyses and may well
serve as a model in other branches of science where there is a need to compare
data and complex simulations.Comment: 4 pages, 4 postscript figures, uses CHEP2004.cls. Presented at
Computing in High-Energy Physics (CHEP'04), Interlaken, Switzerland, 27th
September - 1st October 200
Multi-parton correlations and "exclusive" cross sections
In addition to the inclusive cross sections discussed within the QCD-parton
model, in the regime of multiple parton interactions, different and more
exclusive cross sections become experimentally viable and may be suitably
measured. Indeed, in its study of double parton collisions, the quantity
measured by CDF was an "exclusive" rather than an inclusive cross section. The
non perturbative input to the "exclusive" cross sections is different with
respect to the non perturbative input of the inclusive cross sections and
involves correlation terms of the hadron structure already at the level of
single parton collisions. The matter is discussed in details keeping explicitly
into account the effects of double and of triple parton collisions.Comment: 18 pages, no figures, corrected typo
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