Speaker: Rodolfo Sassot (Buenos Aires U.) 

Title: Recent progress in the pQCD description of SIDIS

Semi-inclusive processes have the virtue -or defect- of involving 
the three main ingredients of perturbative QCD, namely, hard cross
sections, which can be computed with all the artillery of 
perturbation theory, the partonic structure  of the nucleon previous 
the hard interaction, very precisely parameterized in terms of current 
parton distribution functions (PDFs), and the hadronization process 
that follows it, in turn described by fragmentation functions (FFs) 
of increasing accuracy. The obvious caveat, of course, is that the 
insight we can get on any of the three ingredients, depends on how 
precise is our knowledge on the others.

In the first part of may talk I will summarize recent developments 
involving fragmentation functions. In the second, I'll show as an 
example how these results impact the extraction of polarized parton 
densities in combined analyses of inclusive and semi-inclusive deep 
inelastic scattering data together with the latest RHIC polarized data. 
Finally I will discuss some preliminary work on nuclear modification 
of fragmentation functions also based on SIDIS data.