Title: 

"The Drell-Yan program at COMPASS"

Catarina Quintans, LIP


Abstract:
Now entering a second phase of experimental measurements, COMPASS proposes to study the nucleon spin structure 
in view of the most recent theoretical developments in the field, like the GPDs and the TMDs approaches. Up to 
now, TMDs have been studied in COMPASS in SIDIS processes. The experiment will now proceed by performing a 
novel, complementary extraction of these PDFs, using the Drell-Yan process.

The Drell-Yan events produced from the collision of a negative pion beam with 190 GeV/c momentum with an ammonia 
target, either unpolarized or transversely polarized, will allow the study of proton and pion TMDs. According to 
the existing predictions for the azimuthal asymmetries, sizable effects are to be expected, allowing namely to 
check the sign change of Sivers and Boer-Mulders TMDs when viewed from SIDIS or from Drell-Yan processes.

The details of the planned COMPASS  Drell-Yan experiment will be presented,
including the expected events rates, the statistical precision, and systematics involved. Other important research 
topics that can be studied in parallel will also be discussed, like the Drell-Yan - J/psi duality.