The role of hadronization mechanism in polarization phenomena in semi
inclusive deep inelastic scattering (SIDIS) and a purity method for extraction
of polarized distribution functions are discussed. According to the Monte Carlo
(MC) event generator, on which this method is based, hadrons can be produced
via quark (diquark) fragmentation or light cluster decays. In contrast, the
purity method assumes that only quark fragmentation gives contribution to
hadron production in the current fragmentation region. The ignorance of
contributions from diquark fragmentation and cluster decays to asymmetry can be
source of incorrect values of polarized quark distributions extracted by the
purity method.Comment: 5 pages, 2 figure