1,533 research outputs found
The Nuclear Modification Factor at Large Rapidities
RHIC data on high- hadron production display strong suppression in a
wide rapidity region, indicating strong induced energy loss for both
transversally and longitudinally traveling partons. We investigate the
interplay of energy loss and rapidity dependence in a perturbative QCD improved
parton model, and estimate the opacity of the produced hot matter in
collisions at energies GeV and 63 GeV at different
rapidity values. Direction-dependent suppression offers the possibility to
study the geometry of the hot matter.Comment: 4 pages, 2 figures, Contribution to the Poster Proceedings of the
Quark Matter 2005 Conference. To be published in Nuclear Physics
Underlying events in p+p collisions at LHC energies
General properties of hadron production are investigated in proton-proton
collisions at LHC energies. We are interested in the characteristics of hadron
production outside the identified jet cones. We improve earlier definitions and
introduce surrounding rings/belts around the cone of identified jets. In this
way even multiple jet events can be studied in details. We define the
underlying event as collected hadrons from outside jet cones and outside
surrounding belts, and investigate the features of these hadrons. We use a
PYTHIA generated data sample of proton-proton collisions at s = (7 TeV)^2. This
data sample is analysed by our new method and the widely applied CDF method.
Angular correlations and momentum distributions have been studied and the
obtained results are compared and discussed.Comment: 5 pages, 5 figures, to appear in the EPJ Web of Conferences,
Proceedings of the International Workshop on Hot and Cold Baryonic Matter
2010 (Budapest, Hungary, 15-20 August 2010
Where Does the Energy Loss Lose Strength?
Nuclear modification factors for pion production in AuAu and CuCu collisions
are analyzed at very high transverse momenta. At p_T > 10 GeV/c, the
R_{AA}(p_T) is determined mostly by the initial state nuclear modifications
(e.g. EMC effect) and the non-Abelian jet-energy loss in the final state. At
high momenta these effects together are strong enough to suppress R_{AA}(p_T)
to below 1 at RHIC energies. We display results using HKN shadowing in our pQCD
improved parton model. Result of a similar calculation at LHC energies for PbPb
collisions are also displayed. Based on dN/dy estimates, a larger opacity
value, L/\lambda_g = 10 +/- 2, is used for the produced partonic matter in
central collisions at the LHC.Comment: QM 2008, Submitted to Jour. Phys. G, 4 pages and 4 figure
Underlying Event Studies for LHC Energies
Underlying event was originally defined by the CDF collaboration decades ago.
Here we improve the original definition to extend our analysis for events with
multiple-jets. We introduce a definition for surrounding rings/belts and based
on this definition the jet- and surrounding-belt-excluded areas will provide a
good underlying event definition. We inverstigate our definition via the
multiplicity in the defined geometry. In parallel, mean transverse momenta of
these areas also studied in proton-proton collisions at TeV LHC
energy.Comment: 6 pages and 4 figure
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