29 research outputs found
Renormalon Model Predictions for Power-Corrections to Flavour Singlet Deep Inelastic Structure Functions
We analyze power corrections to flavour singlet deep inelastic scattering
structure functions in the framework of the infrared renormalon model. Our
calculations, together with previous results for the non-singlet contribution,
allow to model the x-dependence of higher twist corrections to F_2, F_L and g_1
in the whole x domain.Comment: LaTeX, 25 pages, 8 eps figures included, one figure was added. Final
version for publication in Nucl.Phys.
Transverse Polarisation of Quarks in Hadrons
We review the present state of knowledge regarding the transverse
polarisation (or transversity) distributions of quarks. After some generalities
on transverse polarisation, we formally define the transversity distributions
within the framework of a classification of all leading-twist distribution
functions. We describe the QCD evolution of transversity at leading and
next-to-leading order. A comprehensive treatment of non-perturbative
calculations of transversity distributions (within the framework of quark
models, lattice QCD and QCD sum rules) is presented. The phenomenology of
transversity (in particular, in Drell-Yan processes and semi-inclusive
leptoproduction) is discussed in some detail. Finally, the prospects for future
measurements are outlined.Comment: small changes, references added, as finally published in Physics
Report
Spin Structure of the Proton from Polarized Inclusive Deep-Inelastic Muon-Proton Scattering
We have measured the spin-dependent structure function in inclusive
deep-inelastic scattering of polarized muons off polarized protons, in the
kinematic range and . A
next-to-leading order QCD analysis is used to evolve the measured
to a fixed . The first moment of at is .
This result is below the prediction of the Ellis-Jaffe sum rule by more than
two standard deviations. The singlet axial charge is found to be . In the Adler-Bardeen factorization scheme, is
required to bring in agreement with the Quark-Parton Model. A
combined analysis of all available proton and deuteron data confirms the
Bjorken sum rule.Comment: 33 pages, 22 figures, uses ReVTex and smc.sty. submitted to Physical
Review
Probing Nucleon Spin Structure
One of the important questions in high energy physics is the relation of
quark and gluon spin to that of the nucleons which they comprise. Polarization
experiments provide a mechanism to probe the spin properties of elementary
particles and provide crucial tests of Quantum Chromodynamics (QCD). The
theoretical and experimental status of this fundamental question will be
reviewed in this paper.Comment: 65 pages, 3 Postscript figures, LaTeX. To be published in "Progress
in Particle and Nuclear Physics
Determination of nutrient salts by automatic methods both in seawater and brackish water: the phosphate blank
9 páginas, 2 tablas, 2 figurasThe main inconvenience in determining nutrients in seawater by automatic methods is simply solved:
the preparation of a suitable blank which corrects the effect of the refractive index change on the recorded
signal. Two procedures are proposed, one physical (a simple equation to estimate the effect) and the other
chemical (removal of the dissolved phosphorus with ferric hydroxide).Support for this work came from CICYT (MAR88-0245 project) and
Conselleria de Pesca de la Xunta de GaliciaPeer reviewe
Johann Gottfried Walther als Theoretiker von Hermann Gehrmann.
Vita. --- Inaugural-Dissertation zur Erlangung der Doktorwèurde von der Philosophischen Fakultèat der Kèoniglichen Friedrich-Wilhelms-Universitèat zu Berlin
Vergleich von thermischen Verfahren zur Nutzung von Rückständen aus der Bioethanolerzeugung und Zuckerherstellung in Brasilien
Within the BMBF-funded Brazilian-German cooperation project ASHES, the thermal utilization of bagasse and other residuals from the sugar processing industry was examined. In the laboratory scale, tests were carried out on the KLEAA system of the KIT-ITC to determine relevant fuel parameters. Subsequently, Fraunhofer UMSICHT carried out tests on combustion plants on a technical scale with different plant sizes of 30 kW, 100 kW and 440 kW. The primary objective was to gain knowledge regardimg the combustion and emission behavior of these fuels. Experiments were also carried out at the CUTEC's ArtFuel facility, a gasification unit in the pilot plant scale, and thus gained information regarding the gasification behavior of bagasse and other residuals from sugar cane processing industry. These findings were used to identify optimization potentials at various points and elaborate concepts for their improvement. Within in the next steps of the project future development of these concepts will be focused. In cooperation with the Brazilian project partners several of these concepts should be implemented into practice after the project