12 research outputs found
Standard Model Higgs boson production in association with a top anti-top pair at NLO with parton showering
We present predictions for the production cross section of a Standard Model
Higgs boson in association with a top-antitop pair at next-to-leading order
accuracy using matrix elements obtained from the HELAC-Oneloop package. The NLO
prediction was interfaced to the PYTHIA and HERWIG shower Monte Carlo programs
with the help of POWHEG-Box, allowing for decays of massive particles,
showering and hadronization, thus leading to final results at the hadron level.Comment: 14 pages, 9 figure
Tevatron-for-LHC Report of the QCD Working Group
The experiments at Run 2 of the Tevatron have each accumulated over 1 inverse
femtobarn of high-transverse momentum data. Such a dataset allows for the first
precision (i.e. comparisons between theory and experiment at the few percent
level) tests of QCD at a hadron collider. While the Large Hadron Collider has
been designed as a discovery machine, basic QCD analyses will still need to be
performed to understand the working environment. The Tevatron-for-LHC workshop
was conceived as a communication link to pass on the expertise of the Tevatron
and to test new analysis ideas coming from the LHC community. The TeV4LHC QCD
Working Group focussed on important aspects of QCD at hadron colliders: jet
definitions, extraction and use of Parton Distribution Functions, the
underlying event, Monte Carlo tunes, and diffractive physics. This report
summarizes some of the results achieved during this workshop.Comment: 156 pages, Tevatron-for-LHC Conference Report of the QCD Working
Grou
Photon-pair jet production via gluon fusion at the LHC
Photon-pair direct or jet-associated productions are important for relevant
standard model measurement, Higgs and new physics searches at the LHC. The
loop-induced gluon-fusion process gg -> \gamma\gamma g, which although formally
contributes only at the next-to-next-to-leading order to \gamma\gamma j
productions, may get enhanced by the large gluon flux at the LHC. We have
checked and confirmed previous results on gg -> \gamma\gamma, \gamma\gamma g at
one loop, using now the traditional Feynman diagram based approach and taking
into account the quark mass effects, and further updated them for the 7 and 14
TeV LHC with new inputs and settings. We provide the details and results of the
calculations, which involves manipulation of rank-5 pentagon integrals. Our
results show that the gluon-fusion process can contribute about 10% of the Born
result, especially at small M_{\gamma\gamma} and PT_{\gamma\gamma}, and
increase further the overall scale uncertainty. Top quark loop effects are
examined in detail, which shows importance near or above the threshold
M_{\gamma\gamma} \gsim 2m_t.Comment: 10 pages, 5 figure
Hard Interactions of Quarks and Gluons: a Primer for LHC Physics
In this review article, we develop the perturbative framework for the
calculation of hard scattering processes. We undertake to provide both a
reasonably rigorous development of the formalism of hard scattering of quarks
and gluons as well as an intuitive understanding of the physics behind the
scattering. We emphasize the importance of logarithmic corrections as well as
power counting of the strong coupling constant in order to understand the
behavior of hard scattering processes. We include "rules of thumb" as well as
"official recommendations", and where possible seek to dispel some myths.
Experiences that have been gained at the Fermilab Tevatron are recounted and,
where appropriate, extrapolated to the LHC.Comment: 118 pages, 107 figures; to be published in Reports on Progress in
Physic