1,180 research outputs found
The \pt spectrum of heavy quarks in photoproduction
We illustrate a formalism that allows to match the next-to-leading order
cross section for the photoproduction of heavy quarks to the cross section
obtained by resumming logarithms of \pt/m to the next-to-leading accuracy,
thus giving a sensible prediction for any value of \pt. We present a
comparison between our predictions and H1 and ZEUS data.Comment: 4 pages Latex; 3 figures included. Talk given at DIS01, 27 April - 1
May 2001, Bologna, Ital
NLO QCD corrections in Herwig++ with MC@NLO
We present the calculations necessary to obtain next-to-leading order QCD
precision with the Herwig++ event generator using the MC@NLO approach, and
implement them for all the processes that were previously available from
Fortran HERWIG with MC@NLO. We show a range of results comparing the two
implementations. With these calculations and recent developments in the
automatic generation of NLO matrix elements, it will be possible to obtain NLO
precision with Herwig++ for a much wider range of processesComment: 26 pages, 28 figure
The p_T Spectrum in Heavy-Flavour Photoproduction
We consider the transverse-momentum distribution of heavy flavours in
photon-hadron collisions. We present a formalism in which large
transverse-momentum logarithms are resummed to the next-to-leading level, and
mass effects are included exactly up to order alpha_em alpha_s^2, so as to
retain predictivity at both small and large transverse momenta.
Phenomenological applications relevant to charm photoproduction at HERA are
given.Comment: 26 pages, Latex, epsfig, 15 figures. Submitted to JHE
Heavy Flavour Production in Two-Photon Collisions
We review the production of charm and bottom quarks in two-photon collisions
at e+e- colliders. The next-to-leading order QCD predictions for total cross
sections and differential distributions are compared with recent experimental
results.Comment: 6 pages, 2 figures. Talk given at the UK Phenomenology Workshop on
Collider Physics, Durham, England, 19-24 Sep 199
Physics at Large Rapidities in Hadrons at LEP2
We compute the order-\as corrections to the total cross section and to jet
rates in hadrons for the process \epem\to\epem +
hadrons. We use a NLO order general-purpose partonic Monte Carlo event
generator that allows the computation of a rate differential in the produced
leptons and hadrons. We compare our results with the experimental data for
\epem\to\epem + hadrons at LEP2.Comment: 5 pages, 1 figure, presented at the LEPTRE meeting, Roma 200
Matching parton showers to NLO computations
We give a prescription for attaching parton showers to next-to-leading order
(NLO) partonic jet cross sections in electron-positron annihilation. Our method
effectively extends to NLO the scheme of Catani, Krauss, Kuhn, and Webber for
matching between m hard jets and (m+1) hard jets. The matching between parton
splitting as part of a shower and parton splitting as part of NLO matrix
elements is based on the Catani-Seymour dipole subtraction method that is
commonly used for removing the singularities from the NLO matrix elements.}Comment: 45 pages, new introduction, more detailed discussion of the Sudakov
reweightin
Soft-gluon effects in WW production at hadron colliders
We consider QCD radiative corrections to WW pair production in hadron
collisions. We perform a calculation that consistently combines next-to-leading
order predictions with soft-gluon resummation valid at small transverse momenta
ptWW of the WW pair. We present results for the ptWW distribution at the LHC up
to (almost) next-to-next-to-leading logarithmic accuracy, and study the effect
of resummation on the charged-lepton distributions. Soft-gluon effects are
typically mild, but they can be strongly enhanced when hard cuts are applied.
The relevant distributions are generally well described by the MC@NLO event
generator.Comment: 15 pages, 12 postscript figures. Error corrected in NLO plot for WW
transverse-mass distribution. Results unchange
Electroweak and QCD corrections to top-pair hadroproduction in association with heavy bosons
We compute the contribution of order to the cross
section of a top-antitop pair in association with at least one heavy Standard
Model boson -- , , and Higgs -- by including all effects of QCD, QED,
and weak origin and by working in the automated MadGraph5_aMC@NLO framework.
This next-to-leading order contribution is then combined with that of order
, and with the two dominant lowest-order ones,
and , to obtain phenomenological results
relevant to a 8, 13, and 100~TeV collider.Comment: 27 pages, 8 figure
Recent Results from SELEX
The SELEX experiment (E781) is 3-stage magnetic spectrometer for the study of
charm hadroproduction at large xF using 600 Gev Sigma-, pi- and p beams. New
precise measurements of the Lambda_c, D0, and Ds lifetimes are presented. We
also report results on Lambda_c and Ds production by Sigma-, pi- and p beams at
xF>0.2. The data agree with expectations from color-drag models to explain
charm particle/antiparticle production asymmetries.Comment: 3 pages, 1 figure. Talk given by J.Russ at the XXXth International
Conference on High Energy Physics July 27 - August 2, 2000, Osaka, Japan.
Proceedings to be published by World Scientifi
Weak corrections to Higgs hadroproduction in association with a top-quark pair
We present the calculation of the next-to-leading contribution of order
to the production of a Standard Model Higgs boson in
association with a top-quark pair at hadron colliders. All effects of weak and
QCD origin are included, whereas those of QED origin are ignored. We work in
the MadGraph5_aMC@NLO framework, and discuss sample phenomenological
applications at a 8, 13, and 100 TeV collider, including the effects of
the dominant next-to-leading QCD corrections of order .Comment: 29 pages, 38 figure
- …