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Godparent
Committees
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Jet Evolution and the Underlying Event in Proton-Antiproton Collisions at 1.8 TeV
(draft)
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Mike Albrow, Aesook Byon-Wagner, and Seog Oh. |
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Abstract:
The growth and development of "charged particle jets" produced in proton-antiproton
collisions at 1.8 TeV are studied. A variety of "local" leading jet observables are
compared with the QCD "hard scattering" Monte-Carlo models of Herwig, Isajet, and Pythia.
The models describe quite well (although not completely) the multiplicity distribution of
charged particles within the leading jet, the "size" of the leading jet, the radial flow of
charged particles and transverse momentum around the leading jet direction, and the momentum
distribution of charged particles within the leading jet. Also, a number of "global"
observables are examined, where to fit the observable the QCD Monte-Carlo models have to
describe correctly the entire proton-antiproton event structure. In particular, we study
carefully the growth and structure of the "underlying event" in hard scattering processes.
None of the models (with their default parameters) describe correctly all the properties of
the underlying event.
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Dijet Production by Double Pomeron Exchange at the Fermilab Tevatron
(draft)
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Andy Beretvas, Anwar Bhatti, and G. Bellettini. |
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Abstract:
We report the first observation of dijet events with a double pomeron
exchange topology produced in proton-antiproton collisions at 1800 GeV.
The events are characterized by a leading antiproton, two jets in the central
pseudorapidity region, and a large rapidity gap on the outgoing proton side.
We present results on jet kinematics and production rates, compare them with
corresponding results from single diffractive and inclusive dijet production,
and test factorization.
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Jet Fragmentation in Dijet and Gamma-Jet Events (Modified Leading Log Approximation)
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Luc Demortier, Rob Plunkett, and Alberto Ribon. |
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Abstract:
Studies of the jet fragmentation at CDF. Average multiplicities and momentum
distributions of hadrons in jets are compared to and found to agree with the predictions of
Modified Leading Log Approximation (MLLA), which assumes perturbative nature of the jet fragmentation down to
momentum transfer scales as low as kT/Lambda_QCD. Special attention was paid to extraction of
the ratio r of charged particle multiplicities in gluon and quark jets, which was measured both
in the context of MLLA calculations and in a model-independent way by analyzing jet-jet and
gamma-jet data. The measurements are self-consistent and agree with the perturbative QCD
predictions.
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