64 research outputs found
Constraints on "Second Order Fixed Point" QCD from the CCFR Data on Deep Inelastic Neutrino-Nucleon Scattering
The results of LO {\it Fixed point} QCD (FP-QCD) analysis of the CCFR data
for the nucleon structure function are presented. The
predictions of FP-QCD, in which the Callan-Symanzik function admits a
{\it second order} ultraviolet zero at are in good
agreement with the data. Constraints for the possible values of the
function parameter regulating how fast tends to its
asymptotic value are found from the data. The corresponding
values of are also determined. Having in mind our recent " First
order fixed point" QCD fit to the same data we conclude that in spite of the
high precision and the large kinematic range of the CCFR data they
cannot discriminate between QCD and FP-QCD predictions for .Comment: 8 pages, LaTe
The Role of Higher Twist in Determining Polarized Parton Densities from DIS data
Different methods to extract the polarized parton densities from the world
polarized DIS data are considered. The higher twist corrections to
the spin dependent proton and neutron structure functions are found to be
non-negligible and important in the QCD analysis of the present experimental
data. Their role in determining the polarized parton densities in the framework
of the different approaches is discussed.Comment: To appear in the Proceedings of the Spin2004 Symposium, Trieste,
11-16 Oct 200
Status of Longitudinal Polarized Parton Densities and Higher Twist
The present status of the longitudinal polarized parton densities (PDFs) and
the contribution of their first moments to the nucleon spin is discussed.
Special attention is paid to the role of higher twist effects in determining
the PDFs and to the polarized strange quark and gluon densities, which are
still not well determined from the present data.Comment: 6 pages, 5 figures; to appear in the proceedings of the 18th
International Symposium on Spin Physics (SPIN20008), October 6 - 11, 2008,
Charlottesville, Virginia, US
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