9,337 research outputs found
Gluon Radiation in Top Quark Production and Decay at an e^+ e^- Collider
We study the effects of gluon radiation on top production and decay processes
at an collider.The matrix elements are computed without any
approximations, using spinor techniques. We use a Monte Carlo event generator
which takes into account the infrared singularity due to soft gluons and
differences in kinematics associated with radiation in the production versus
decay process. The calculation is illustrated for several strategies of top
mass reconstruction.Comment: 9 pages, LaTeX, 6 postscript figures, uses aipproc.sty; presented at
the 20th annual MRST meeting on High-Energy Physics, Montreal, Canada, 13-15
May 199
Preliminary feasibility analysis of a pressure modulator radiometer for remote sensing of tropospheric constituents
A pressure modulator radiometer operated in a nadir viewing mode from the top of a midlatitude summer model of the atmosphere was theoretically studied for monitoring the mean volumetric mixing ratio of carbon monoxide in the troposphere. The mechanical characteristics of the instrument on the Nimbus 7 stratospheric and mesospheric sounder experiment are assumed and CO is assumed to be the only infrared active constituent. A line by line radiative transfer computer program is used to simulate the upwelling radiation reaching the top of the atmosphere. The performance of the instrument is examined as a function of the mean pressure in and the length of the instrument gas correlation cell. Instrument sensitivity is described in terms of signal to noise ratio for a 10 percent change in CO mixing ratio. Sensitivity to mixing ratio changes is also studied. It is concluded that tropospheric monitoring requires a pressure modulator drive having a larger swept volume and producing higher compression ratios at higher mean cell pressures than the Nimbus 7 design
QCD: Challenges for the Future
Despite many experimental verifications of the correctness of our basic
understanding of QCD, there remain numerous open questions in strong
interaction physics and we focus on the role of future colliders in addressing
these questions. We discuss possible advances in the measurement of ,
in the study of parton distribution functions, and in the understanding of low
physics at present colliders and potential new facilities. We also touch
briefly on the role of spin physics in advancing our understanding of QCD.Comment: 12 pages, LATEX2e with snow2e, epsfig and 2 figures. Also available
at http://penguin.phy.bnl.gov/~dawson/qcdsnow.ps . QCD working group summary
at DPF/DPB Summer Study on New Directions for High Energy Physics, Snowmass,
CO, June 25- July 12, 199
Theoretical progress for the associated production of a Higgs boson with heavy quarks at hadron colliders
The production of a Higgs boson in association with a pair of top-antitop or
bottom-antibottom quarks plays a very important role at both the Tevatron and
the Large Hadron Collider. The theoretical prediction of the corresponding
cross sections has been improved by including the complete next-to-leading
order QCD corrections. After a brief introduction, we review the results
obtained for both the Tevatron and the Large Hadron Collider.Comment: 3 pages, 6 figures, uses svjour.cls. Talk given by L. Reina at the
HEP2003 Europhysics Conference in Aachen, Germany (EPS 2003), July 17-23,
200
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