5,372 research outputs found
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
Resummation of the transverse-energy distribution in Higgs boson production at the Large Hadron Collider
We compute the resummed hadronic transverse-energy () distribution due
to initial-state QCD radiation in the production of a Standard Model Higgs
boson of mass 126 GeV by gluon fusion at the Large Hadron Collider, with
matching to next-to-leading order calculations at large . Effects of
hadronization, underlying event and limited detector acceptance are estimated
using aMC@NLO with the Herwig++ and Pythia 8 event generators.Comment: 26 pages, 13 figures. Version to appear in JHE
Monte Carlo simulation of baryon and lepton number violating processes at high energies
We report results obtained with the first complete event generator for
electroweak baryon and lepton number violating interactions at supercolliders.
We find that baryon number violation would be very difficult to establish, but
lepton number violation can be seen provided at least a few hundred L violating
events are available with good electron or muon identification in the energy
range 10 GeV to 1 TeV.Comment: 40 Pages uuencoded LaTeX (20 PostScript figures included),
Cavendish-HEP-93/6, CERN-TH.7090/9
Associated jet and subjet rates in light-quark and gluon jet discrimination
We show that in studies of light quark- and gluon-initiated jet
discrimination, it is important to include the information on softer
reconstructed jets (associated jets) around a primary hard jet. This is
particularly relevant while adopting a small radius parameter for
reconstructing hadronic jets. The probability of having an associated jet as a
function of the primary jet transverse momentum () and radius, the minimum
associated jet and the association radius is computed upto next-to-double
logarithmic accuracy (NDLA), and the predictions are compared with results from
Herwig++, Pythia6 and Pythia8 Monte Carlos (MC). We demonstrate the improvement
in quark-gluon discrimination on using the associated jet rate variable with
the help of a multivariate analysis. The associated jet rates are found to be
only mildly sensitive to the choice of parton shower and hadronization
algorithms, as well as to the effects of initial state radiation and underlying
event. In addition, the number of subjets of an anti- jet is found
to be an observable that leads to a rather uniform prediction across different
MC's, broadly being in agreement with predictions in NDLA, as compared to the
often used number of charged tracks observable.Comment: 25 pages, 12 figures; v2: Figures of 2D joint distributions included,
additions to text and Refs., version to appear in JHE
Quark-gluon discrimination in the search for gluino pair production at the LHC
We study the impact of including quark- and gluon-initiated jet
discrimination in the search for strongly interacting supersymmetric particles
at the LHC. Taking the example of gluino pair production, considerable
improvement is observed in the LHC search reach on including the jet
substructure observables to the standard kinematic variables within a
multivariate analysis. In particular, quark and gluon jet separation has higher
impact in the region of intermediate mass-gap between the gluino and the
lightest neutralino, as the difference between the signal and the standard
model background kinematic distributions is reduced in this region. We also
compare the predictions from different Monte Carlo event generators to estimate
the uncertainty originating from the modelling of the parton shower and
hadronization processes.Comment: 22 pages, 8 figures, 1 table; v2: statistical treatment improved and
figures update
The effects of newly measured cross sections in hydrogen on the production of secondary nuclei during the propagation of cosmic rays through interstellar H
The cross sections of six important cosmic ray source nuclei in hydrogen at several energies between 300 and 1800 MeV/nuc were measured. Significant differences, sometimes exceeding 50%, exist between these new measurements and the earlier semiempirical predictions, and a new set of semiempirical formulae are being determined that better describe this fragmentation. New cross sections were obtained so that the systematics of their effects on cosmic ray propagation through interstellar hydrogen can be examined
Communique, 26 January 2004
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