11,013 research outputs found
The Extraction of the Gluon Density from Jet Production in Deeply Inelastic Scattering
The prospects of a direct extraction of the proton's gluon density in
next-to-leading order via jet rates in deeply inelastic scattering are studied.
The employed method is based on the Mellin transform, and can be applied, in
principle, to all infra-red-safe observables of hadronic final states. We
investigate the dependence of the error band on the extracted gluon
distribution on the statistical and systematic error of the data.Comment: 5 pages (Latex); 2 figures are included via epsfig; contribution to
the workshop ``Future Physics at HERA'' at DESY, Hamburg, 1995/96; to be
published in the proceedings; compressed postscript version also available at
http://wwwcn.cern.ch/~graudenz/publications.htm
The uniqueness of the invariant polarisation-tensor field for spin-1 particles in storage rings
We argue that the invariant tensor field introduced in [1] is unique under
the condition that the invariant spin field is unique, and thereby complete
that part of the discussion in that paper.Comment: 8 page
Heavy flavor in heavy-ion collisions at RHIC and RHIC II
In the initial years of operation, experiments at the Relativistic Heavy Ion
Collider (RHIC) have identified a new form of matter formed in nuclei-nuclei
collisions at energy densities more than 100 times that of a cold atomic
nucleus. Measurements and comparison with relativistic hydrodynamic models
indicate that the matter thermalizes in an unexpectedly short time, has an
energy density at least 15 times larger than needed for color deconfinement,
has a temperature about twice the critical temperature predicted by lattice
QCD, and appears to exhibit collective motion with ideal hydrodynamic
properties - a "perfect liquid" that appears to flow with a near-zero viscosity
to entropy ratio - lower than any previously observed fluid and perhaps close
to a universal lower bound. However, a fundamental understanding of the medium
seen in heavy-ion collisions at RHIC does not yet exist. The most important
scientific challenge for the field in the next decade is the quantitative
exploration of the new state of nuclear matter. That will require new data that
will, in turn, require enhanced capabilities of the RHIC detectors and
accelerator. In this report we discuss the scientific opportunities for an
upgraded RHIC facility - RHIC II - in conjunction with improved capabilities of
the two large RHIC detectors, PHENIX and STAR. We focus solely on heavy flavor
probes. Their production rates are calculable using the well-established
techniques of perturbative QCD and their sizable interactions with the hot QCD
medium provide unique and sensitive measurements of its crucial properties
making them one of the key diagnostic tools available to us.Comment: 96 pages, 53 figures. Accepted for publication in Physics Reports.
Fixed typo in Fig. 15 captio
Narrowing the uncertainty on the total charm cross section and its effect on the J/\psi\ cross section
We explore the available parameter space that gives reasonable fits to the
total charm cross section to make a better estimate of its true uncertainty. We
study the effect of the parameter choices on the energy dependence of the
J/\psi\ cross section.Comment: 19 pages, 13 figure
The Mellin Transform Technique for the Extraction of the Gluon Density
A new method is presented to determine the gluon density in the proton from
jet production in deeply inelastic scattering. By using the technique of Mellin
transforms not only for the solution of the scale evolution equation of the
parton densities but also for the evaluation of scattering cross sections, the
gluon density can be extracted in next-to-leading order QCD. The method
described in this paper is, however, more general, and can be used in
situations where a repeated fast numerical evaluation of scattering cross
sections for varying parton distribution functions is required.Comment: 13 pages (LaTeX); 2 figures are included via epsfig; the
corresponding postscript files are uuencode
Improving the J/psi Production Baseline at RHIC and the LHC
We assess the theoretical uncertainties on the inclusive J/psi production
cross section in the Color Evaporation Model (CEM) using values for the charm
quark mass, renormalization and factorization scales obtained from a fit to the
charm production data. We use our new results to provide improved baseline
comparison calculations at RHIC and the LHC. We also study cold matter effects
on J/psi production at leading relative to next-to-leading order in the CEM
within this approach.Comment: Proceedings for Hard Probes 2012, Cagliari, Ital
Congener specific analysis of polychlorinated terphenyls
In order to identify and to quantify polychlorinated terphenyls (PCT) in environmental matrices, the chro-
matographic behavior of coplanar and non-coplanar congeners was evaluated. A mixture of 16 single PCT
congeners was used for method development. Four of these compounds were synthesized for the first
time by SUZUKI-coupling reaction. These were p-PCT (2,200
,6,600
-tetrachloro-, 20
,3,300
,4,400
,50
,-hexachloro-,
20
,3,300
,5,50
,500
-hexachloro-) and m-PCT (2,200
,3,300
,5,500
-hexachloro-). They were characterized by NMR
(
1
H,
13
C) spectroscopy. By means of the new column chromatographic clean-up reported here, a good
matrix removal and the separation of the coplanar PCT congeners from the non-coplanar ones was
obtained. The recovery rates for all congeners were good for the PCT in different test matrices like fat,
charcoal, and soil. The quality of the clean-up, the separation and the recovery rates were determined
by GC/MS analysis. The method was applied for the first time to a real sample from a fire accident, where
different PCT, obviously formed during the combustion process, were found. The conclusion is drawn that
this method is suitable for the analysis of PCT in different environmental samples
The effect of bedrest on various parameters of physiological function. part viii- the . . . effect on the cardiovascular tolerance to passive tilt
Effect of short and long term bed rest on cardiovascular tolerance to passive til
The effect of bedrest on various parameters of physiological function. part xi- the effect of bedrest on blood volume, urinary volume, and urinary electrolyte excretion
Effect of bed rest on blood volume, urinary volume, and urinary electrolyte excretio
The effect of bedrest on various parameters of physiological function. Part XIII - A review of possible mechanisms of orthostatic intolerance to passive tilt
Possible mechanisms of orthostatic intolerance to passive tilt - bed rest and water immersion effects on various parameters of physiological functio
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