Dr
Christoph Pahl
(MPI for Physics Munich)
7/16/09, 9:00 AM
QCD at Colliders
QCD predictions of hadronic event shapes, in complete 3rd order (NNLO) and in resummed 3rd order (NNLO & NLLA) perturbation theory, are applied to e+e- annihilation data in the c.m. energy range of 14 to 200 GeV, in order to
precisely determine the running coupling alphas(Q). Moments of event shape distributions and respective predictions in NLO QCD are used to test different regions of phase...
Dr
Andreas van Hameren
(IFJ-PAN, Krakow)
7/16/09, 9:15 AM
QCD at Colliders
In order to deal with the data from the experiments at LHC for the
study of elementary particles, signals and potential backgrounds for
new physics have to be under control at sufficient accuracy. In
particular, hard processes with high multiplicities, involving many
particles or partons, cannot be neglected. On top of that, such
processes have to be dealt with at the next-to-leading...
Joerg Behr
(Hamburg University)
7/16/09, 9:30 AM
QCD at Colliders
Jet cross sections in deep inelastic ep scattering (DIS) and photoproduction were measured with the H1 and ZEUS detectors at HERA using data collected in the years 1999-2007 and
corresponding to an integrated luminosity of up to 500 pb-1. Measurements of differential cross sections for inclusive-jet production in DIS and photoproduction are presented together with the tri-jet to di-jet...
Dr
Nirmalya Parua
(Indiana University, Bloomington)
7/16/09, 9:50 AM
QCD at Colliders
We present measurements involving two jets in ppbar collisions
at a center of mass energy of 1.96 TeV with the D0 detector at the Fermilab
Tevatron Collider.
We present dijet angular distributions and invariant mass distributions.
The data are in good agreement with the prediction of perturbative QCD,
and are used to constrain several new physics models including
quark compositeness,...
Claudia Glasman
(Univer. Autonoma De Madrid)
7/16/09, 10:10 AM
QCD at Colliders
Inclusive jet cross sections in charged current deep inelastic scattering (DIS)
and three-jet production in DIS and photoproduction were studied with the ZEUS detector at HERA.
For the study of inclusive jet-production in charged current DIS, differential
cross sections are presented as functions of Q2, Bjorken x and the jet transverse energy
and pseudorapidity. The dijet invariant...
Dr
Maciej Skrzypek
(IFJ-PAN)
7/16/09, 11:00 AM
QCD at Colliders
We report here on the ongoing project, called KRKMC,
in which NLO DGLAP evolution is performed for
the exclusive multiparton distributions
with the help of the exclusive kernels.
These kernels are calculated within the two-parton phase space
for bremsstrahlung subset of the Feynman diagrams of the non-singlet evolution,
using Curci-Furmanski-Petronzio factorization scheme.
The...
Ms
Nele Boelaert
(Lund University - Div. of Experimental High-Energy Physics)
7/16/09, 11:15 AM
QCD at Colliders
Jet production is the most dominant hard process in hadron collision experiments. While jets are background for many new physics searches, jets can also be used as a signal. Because of the rich abundance of jets, many jet studies can be performed with little integrated luminosity.
The dijet angular distribution between the two hardest jets in the event has shown to be a very useful...
Dr
Iacopo Vivarelli
(University of Freiburg)
7/16/09, 11:30 AM
QCD at Colliders
The large uncertainties in the extrapolation at the LHC energies of the current phenomenological models for the track multiplicity and pt spectra in minimum bias events will require a direct measurement with the first data. The strategies developed by ATLAS and CMS are reviewed, with particular emphasis to the minimum bias trigger and low pt tracking efficiency. The ability of the experiment...
Dr
Leonard Apanasevich
(University of Illinios at Chicago)
7/16/09, 11:50 AM
QCD at Colliders
Jet production is the dominant process at the LHC. Studies of jet final states, over the full
range of transverse momenta, are of great importance as they can serve to confront
perturbative QCD calculations, test the extent to which partons are elementary, and
investigate many interesting physics processes within and beyond the standard model.
In this talk, we present the plans and...
Prof.
D0 H1
(DESY, FNAL)
7/16/09, 12:10 PM
QCD at Colliders
Photoproduction data of HERA are analyzed by requiring dijets with transverse momenta of at least 5 GeV. The two jets define in azimuth a towards region (leading jet) and an away region (2nd jet) and transverse regions between them. The charged particle multiplicity is measured in these regions as a function of the variables x_{gamma} and pT_{leading jet}. Models which include contributions...
Dr
Giancarlo Ferrera
(Florence University)
7/16/09, 2:30 PM
QCD at Colliders
We consider QCD radiative corrections and their to the production of vector bosons in hadron collisions.
We present a fully exclusive calculation up to next-to-next-to-leading order (NNLO) in QCD perturbation theory. Our calculation is implemented in a parton level Monte Carlo program which allows the user to apply
arbitrary kinematical cuts on the final-states and to compute the...
Dr
Murilo Rangel
(Laboratoire de l'Accélérateur Linéaire)
7/16/09, 2:45 PM
QCD at Colliders
We present measurements of differential cross sections for the inclusive Z/gamma plus
jet production and for the inclusive photon plus heavy flavor production
in a data sample of 1fb-1 collected with the D0 detector in proton
antiproton collisions at sqrt(s)=1.96TeV.
In the first measurement, we compare kinematic distributions of the
Z/gamma and the jet as well as of the various angles of...
Krzysztof Nowak
(Zuerich University)
7/16/09, 3:05 PM
QCD at Colliders
Prompt-photon cross sections in deep inelastic ep scattering were
measured with the ZEUS detector at HERA using an integrated luminosity
of 320 pb-1. A clear signal for isolated photons in the photon
transverse-energy and rapidity ranges 4 < E_T^gamma < 15 GeV and
-0.7 < eta^gamma < 0.9 was observed for virtualities of the
exchanged photon of Q^2 > 10 GeV^2. Measurements of differential...
Ms
Imai Jen-La Plante
(Enrico Fermi Institute, University of Chicago)
7/16/09, 3:25 PM
QCD at Colliders
Events containing W or Z bosons, with subsequent leptonic decays, are important channels to test the Standard Model. They will be copiously produced at the Large Hadron Collider (LHC). Identification of these events will probe QCD predictions for the associated production of W or Z bosons with one or more jets and will constrain the parton distribution functions of the proton through...
Dr
Tara Shears
(University of Liverpool)
7/16/09, 3:45 PM
QCD at Colliders
We report on studies of W and Z boson production in the LHCb experiment. Strategies for triggering, boson selection and background reduction are described. Prospects for differential cross-section measurement are given, with estimates of statistical and systematic errors. The sensitivity of the differential cross sections to parton density functions is discussed.
Dr
Pedro Jimenez-Delgado
(Technische Universität Dortmund)
7/16/09, 4:30 PM
QCD at Colliders
Utilizing recent DIS measurements and Drell-Yan data we determine at NNLO (3-loop) of QCD the dynamical parton distribution functions of the nucleon generated radiatively from valencelike positive input distributions at an optimally chosen low resolution scale. These are compared with ``standard'' NNLO distributions generated from positive input distributions at some fixed and higher...
Jan Kretzschmar
(University of Liverpool)
7/16/09, 4:45 PM
QCD at Colliders
Measurements of the inclusive ep scattering cross section are presented in the region of low to medium momentum transfers, 0.2 GeV^2 < Q^2 < 150 GeV^2, and Bjorken x, 5x10^-6 < x < 0.1. The results are based on data sets collected by the H1 Collaboration at HERA at positron beam energies of 27.6 GeV and proton beam energies of 820 or 920 GeV. A combination with data previously published by H1...
Burkard Reisert
(Max-Planck-Institut für Physik, München)
7/16/09, 5:05 PM
QCD at Colliders
The reduced cross sections for ep deep inelastic scattering have been measured with the ZEUS and H1 detectors at HERA at three different centre-of-mass energies, 318, 251 and 225 GeV. From the cross sections, measured double differentially in Bjorken x and the virtuality, Q2, the proton structure
functions F_L and F_2 have been extracted in a wide kinematic region. The measurements are...
Juan Terron
(Univer. Autonoma De Madrid)
7/16/09, 5:25 PM
QCD at Colliders
Jet cross sections in deep inelastic ep scattering and photoproduction were measured with the ZEUS detector at HERA using an integrated luminosity of up to 500 pb-1. Measurements of differential cross sections are presented for dijet production and compared with perturbative QCD predictions. Regions of phase space where the cross sections are sensitive to the gluon content of the proton with...
Ms
Voica Radescu
(DESY)
7/16/09, 5:45 PM
QCD at Colliders
Deep inelastic scattering cross section measurements previously published by the H1 and ZEUS collaborations are combined. The procedure takes into account the systematic error correlations in a coherent approach, leading to a significantly reduced overall cross section uncertainty by cross calibrating the various data sets. The analysis is based on data with momentum transfers Q^2 > 0.045...
