404 research outputs found
W Plus Heavy Quark Production at the Tevatron
We summarize the motivations for and the status of the calculation of the heavy quark production process in colliders to Next-to-Leading
Order in QCD. This process can be used to constrain the strange quark
distribution function at high at the Tevatron, and also to study the
bottom content of ~jet events. In addition, when crossed, the calculation
essentially describes the single top quark production process to
Next-to-Leading Order in QCD.Comment: Presented by S. Keller at DPF94 Meeting, Albuquerque, New Mexico,
August 1-6,1994. 4 pages, no macros, no figures. Fermilab-Conf-94/260-T,
FSU--HEP--940817. A postscript file is available via anonymous ftp at
hepsg1.physics.fsu.edu, file is /pub/keller/fsu-hep-940817.p
Virtual QCD corrections to Higgs boson plus four parton processes
We report on the calculation of virtual processes contributing to the
production of a Higgs boson and two jets in hadron-hadron collisions. The
coupling of the Higgs boson to gluons, via a virtual loop of top quarks, is
treated using an effective theory, valid in the large top quark mass limit. The
calculation is performed by evaluating one-loop diagrams in the effective
theory. The primary method of calculation is a numerical evaluation of the
virtual amplitudes as a Laurent series in , where is the
dimensionality of space-time. For the cases and we confirm the numerical results by an explicit analytic
calculation.Comment: 21 pages, 2 figures. v2 modifies the text to agree with published
version and corrects typos in the analytical expressions for the four quark
amplitude
Numerical Evaluation of One-Loop Diagrams Near Exceptional Momentum Configurations
One problem which plagues the numerical evaluation of one-loop Feynman
diagrams using recursive integration by part relations is a numerical
instability near exceptional momentum configurations. In this contribution we
will discuss a generic solution to this problem. As an example we consider the
case of forward light-by-light scattering.Comment: 5 pages, 5 figures, Talk given at the 7th DESY Workshop on Elementary
Particle Theory, Loops and Legs in Quantum Field Theory, Zinnowitz 200
Jet Investigations Using the Radial Moment
We define the radial moment, , for jets produced in hadron-hadron
collisions. It can be used as a tool for studying, as a function of the jet
transverse energy and pseudorapidity, radiation within the jet and the quality
of a perturbative description of the jet shape. We also discuss how
non-perturbative corrections to the jet transverse energy affect .Comment: 14 pages, LaTeX, 6 figure
The t-tbar cross-section at 1.8 and 1.96 TeV: a study of the systematics due to parton densities and scale dependence
We update the theoretical predictions for the t-tbar production cross-section
at the Tevatron, taking into account the most recent determinations of
systematic uncertainties in the extraction of the proton parton densities.Comment: 12 pages, 1 figure, Late
Numerical evaluation of one-loop QCD amplitudes
We present the publicly available program NGluon allowing the numerical
evaluation of primitive amplitudes at one-loop order in massless QCD. The
program allows the computation of one-loop amplitudes for an arbitrary number
of gluons. The focus of the present article is the extension to one-loop
amplitudes including an arbitrary number of massless quark pairs. We discuss in
detail the algorithmic differences to the pure gluonic case and present cross
checks to validate our implementation. The numerical accuracy is investigated
in detail.Comment: Talk given at ACAT 2011 conference in London, 5-9 Septembe
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