4,001 research outputs found
Combining QCD Matrix Elements and Parton Showers
A new method for combining QCD matrix elements and parton showers in Monte
Carlo simulations of hadronic final states is outlined. The aim is to provide
at least a leading-order description of all hard multi-jet configurations
together with jet fragmentation to next-to-leading logarithmic accuracy, while
avoiding the most serious problems of double counting.Comment: 6 pages, 8 figures. Talk at XXXV Rencontres de Moriond, Les Arcs,
France, March 200
Fragmentation and Hadronization
Experimental data, theoretical ideas and models concerning jet fragmentation
and the hadronization process are reviewed, concentrating on the following
topics: factorization and small-x resummation of fragmentation functions,
hadronization models, single-particle yields and spectra in Z decay,
comparisons between quark and gluon jets, current and target fragmentation in
deep inelastic scattering, heavy quark fragmentation, Bose-Einstein
correlations and WW fragmentation.Comment: 31 pages, 33 figures. Plenary talk at XIX International Symposium on
Lepton and Photon Interactions at High Energies, Stanford, August 199
The MC@NLO 3.2 Event Generator
This is the user's manual of MC@NLO 3.2. This package is a practical
implementation, based upon the HERWIG event generator, of the MC@NLO formalism,
which allows one to incorporate NLO QCD matrix elements consistently into a
parton shower framework. Processes available in this version include the
hadroproduction of single vector and Higgs bosons, vector boson pairs, heavy
quark pairs, single top, lepton pairs, and Higgs bosons in association with a W
or Z. Spin correlations in decays are included for all processes except ttbar,
single-t, ZZ, and WZ production. This document is self-contained, but we
emphasise the main differences with respect to previous versions.Comment: 23 pages Late
QCD Scaling Violation at Small x
We investigate the evolution of parton densities at small values of the
momentum fraction, x, by including resummed anomalous dimensions in the
renormalization group equations. The resummation takes into account the
leading-logarithmic contributions (\alpha_S \ln x)^k given by the BFKL equation
and the next-to-leading-logarithmic corrections from quark evolution. We
present numerical results for the parton densities and the deep inelastic
structure function F_2.Comment: 8 pages, Latex, 3 uuencoded figure
Power Corrections to Fragmentation Functions in Non-Singlet Deep Inelastic Scattering
We investigate the power-suppressed corrections to the fragmentation
functions of the current jet in non-singlet deep inelastic lepton-hadron
scattering. The current jet is defined by selecting final-state particles in
the current hemisphere in the Breit frame of reference. Our method is based on
an analysis of one-loop Feynman graphs containing a massive gluon, which is
equivalent to the evaluation of leading infrared renormalon contributions. We
find that the leading corrections are proportional to , as in
annihilation, but their functional forms are different. We give quantitative
estimates based on the hypothesis of universal low-energy behaviour of the
strong coupling.Comment: 14 pages, 4 figures, LaTeX2e, uses JHEP.cls (included) and epsfi
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