145 research outputs found
Tests of the extraction of the Sivers, Boer-Mulders and transversity distributions in SIDIS reactions
A major experimental program is presently underway worldwide to determine the
fundamental non-perturbative functions, the Sivers, Boer-Mulders and
transversity distributions, which are vital for an understanding of the
internal structure of the nucleon. However, at present, many simplifying
assumptions are used in extracting these functions from the data. We
demonstrate that if the binning of the data in Q^2 is small enough so that
Q^2-evolution can be neglected inside a bin, then one can obtain stringent
tests of these assumptions. Failure to satisfy these tests implies that the
presently extracted non-perturbative functions are unreliable.
To this end we consider the measurement of the Sivers, Boer-Mulders and
transversity difference asymmetries for hadrons with opposite charges in SIDIS
reactions with unpolarized and transversely polarized deuteron and proton
targets: l+N\to l'+h+X, h=\pi^\pm ,K^\pm ,h^\pm. Utilizing only charge and
isospin invariance, and applying the above mentioned simplifying assumptions we
obtain several testable relations amongst the measured asymmetries. If these
tests are satisfied then the measured asymmetries determine two different
combinations of the valence-quark transverse momentum dependent distributions,
which can be determined separately without any contributions from the strange
and other sea-quarks.Comment: 3 more references and 3 more Sections, where the asymmetries on
proton target are considered are added, there are some changes in the
Abstract and in the Introduction as well; 22 pages, Latex fil
A Model Independent Approach to Semi-Inclusive Deep Inelastic Scattering
We present a method for extraction of detailed information on polarized quark
densities from semi-inclusive deep inelastic scattering l+N -> l+h+X, in both
LO and NLO QCD without any assumptions about fragmentation functions and
polarized sea densities. The only symmetries utilised are charge conjugation
and isotopic spin invariance of strong interactions.Comment: a talk given at the 16th Intern. Spin Physics Symposium, SPIN2004,
Trieste, Italy, 5 page
On Combining High and Low Q**2 Information on the Polarized Parton Densities
We draw attention to some problems in the combined use of high-Q^2 deep
inelastic scattering (DIS) data and low-Q^2 hyperon \beta-decay data in the
determination of the polarized parton densities. We explain why factorization
schemes like the JET or AB schemes are the simplest in which to study the
implications of the DIS parton densities for the physics of the low-Q^2 region.Comment: 10 pages, LaTeX, minor corrections made in Section 4, a reference
added, to be published in JHE
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