3,934 research outputs found
The chirally-odd twist-3 distribution e(x)
Properties of the nucleon twist-3 distribution function e(x) are reviewed. It
is emphasized that the QCD equations of motion imply the existence of a
delta-function at x=0 in e(x), which gives rise to the pion-nucleon sigma-term.
According to the resulting ``practical'' DIS sum rules the first and the second
moment of e(x) vanish, a situation analogue to that of the pure twist-3
distribution function .Comment: 19 pages, 3 figures, new references and figures adde
Azimuthal asymmetries and Collins analyzing power
Spin azimuthal asymmetries in pion electro-production in deep inelastic
scattering off longitudinally polarized protons, measured by HERMES, are well
reproduced theoretically with no adjustable parameters. Predictions for
azimuthal asymmetries for a longitudinally polarized deuteron target are given.
The z-dependence of the Collins fragmentation function is extracted. The first
information on e(x) is extracted from CLAS A_LU asymmetry.Comment: 5 pages, 7 figures. Talk presented by A.V. Efremov at DIS2002,
Cracow, Poland, 30 April to 4 May 2002. To appear in Acta Physica Polonica
Transversity in Drell-Yan process of polarized protons and antiprotons in PAX experiment
Estimates are given for the double spin asymmetry in lepton-pair production
from collisions of transversely polarized protons and antiprotons for the
kinematics of the recently proposed PAX experiment at GSI on the basis of
predictions for the transversity distribution from the chiral quark soliton
model.Comment: 4 pages, 2 eps-figures, style files. To be published in Proceedings
of 16th Intern. spin physics symposium, October 10-16, Trieste, Ital
Collins Effect in SIDIS and in Annihilation
We review the present understanding of the nucleon transversity distribution
and Collins fragmentation function, based on Ref.\cite{Efremov:2006qm}, and
discuss how Drell-Yan experiments will improve it.Comment: Talk at Moscow ICHEP 26.7-2.8.2006 and Kyoto Symposium on Spin
Physics 2-7.10.2006, 5 pages, 5 figures, AIP style files included. Some
pictures chenged, one reference added, typos and some errors in formulas are
correcte
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