197 research outputs found
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Calculation of Chirality Violating Proton Structure Function h(x) in QCD
The twist-two chirality violating proton structure function
measurable in the polarized Drell-Yan process is calculated by means of QCD sum
rules at intermediate , and .Comment: 12 pages + 6 figures , LaTeX, preprint LMU-01-94. a few additions to
the text; the figures have been added as uuencoded fil
Positivity Constraints for Spin-Dependent Parton Distributions
We derive new positivity constraints on the spin-dependent structure
functions of the nucleon. These model independent results reduce conside\-rably
their domain of allowed values, in particular for the chiral-odd parton
distribution .Comment: 8 pages,CPT-94/P.3059,LaTex,3 fig available on cpt.univ-mrs.fr
directory pub/preprints/94/fundamental-interactions/94-P.305
Novel Quark Fragmentation Functions and the Nucleon's Transversity Distribution
We define twist-two and twist-three quark fragmentation functions in Quantum
Chromodynamics (QCD) and study their physical implications. Using this
formalism we show how the nucleon's transversity distribution can be measured
in single pion inclusive electroproduction.Comment: 10 pages, uses PHYZZX macro package, 2 PostScript figures (added
using FIGURES). MIT-CTP-215
Stationary Distribution and Eigenvalues for a de Bruijn Process
We define a de Bruijn process with parameters n and L as a certain
continuous-time Markov chain on the de Bruijn graph with words of length L over
an n-letter alphabet as vertices. We determine explicitly its steady state
distribution and its characteristic polynomial, which turns out to decompose
into linear factors. In addition, we examine the stationary state of two
specializations in detail. In the first one, the de Bruijn-Bernoulli process,
this is a product measure. In the second one, the Skin-deep de Bruin process,
the distribution has constant density but nontrivial correlation functions. The
two point correlation function is determined using generating function
techniques.Comment: Dedicated to Herb Wilf on the occasion of his 80th birthda
Chiral-odd transversity spin structure function of the nucleon in a constituent quark model
We study the chiral-odd transversity spin-dependent quark distribution
function of the nucleon in a constituent quark model. The twist-2
structure functions, , and are calculated within the
diquark spectator approximation. Whereas an inequality holds with the interaction between quark and diquark being scalar, the
axial-vector effective quark-diquark interaction, which contributes to the
-quark distribution, does not lead to such a simple relation. We find that
for the -quark becomes somewhat smaller than , when we
fix the model parameter to reproduce known other structure functions. We also
include corrections due to the non-trivial structure of the constituent quark,
which is modeled by the Goldstone boson dressing. This improves agreements of
and with experiments, and brings further reduction of
distribution. Consequences for semi-inclusive experiments are also
discussed.Comment: 33 pages, latex with 13 figures, to appear in Nuclear Physics A,
PostScript file is also available at
http://WWW.physik.tu-muenchen.de/~ksuzuki/publication.htm
Parton Distributions from W+- and Z Production in Polarized pp and pn Collisions at RHIC
We study the production of and gauge bosons in proton-proton
and proton-neutron collisions up to a center-of-mass energy ,
in connection with the realistic possibility of having proton-deuteron
collisions at RHIC with a high luminosity. We stress the importance of
measuring unpolarized cross sections for a better determination of the flavor
asymmetry of the sea quarks. Since polarized proton beams will be available at
RHIC, we evaluate several spin-dependent observables like, double helicity
asymmetries as a test of the sea quark polarization, double transverse
spin asymmetries as a practical way to determine a new structure
function, the nucleon transversity distribution , and parity-violating
asymmetries as a further test of our present knowledge of polarized
parton distributions.Comment: 16p,CPT-94/P.3000,TEX,19 fig available on cpt.univ-mrs.fr directory
ftp/pub/preprints/94/fundamental-interactions/ 94-P.300
Lorentz invariance relations between parton distributions and the Wandzura-Wilczek approximation
The violation of the so-called Lorentz invariance relations between parton
distribution functions is considered in a model independent way. It is shown
that these relations are not violated in a generalized Wandzura-Wilczek
approximation, indicating that numerically their violation may be small.Comment: 13 pages, added references, minor changes, to appear in Phys. Lett.
Azimuthal single spin asymmetries in SIDIS in the light of chiral symmetry breaking
An attempt is made to understand the z-dependence of the azimuthal single
spin asymmetries observed by the HERMES collaboration in terms of chiral models
based on effective quark and Goldstone boson degrees of freedom. The effects of
respectively neglecting and considering Gaussian intrinsic parton transverse
momenta and the Sivers effect are explored. Predictions for the transverse
target polarization experiment at HERMES are presented.Comment: 14 pages, 18 figure
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