Polarized Drell-Yan measurements at COMPASS.

Longo R.
  Mercoledì 13/09   09:00 - 13:00   Aula A208   I - Fisica nucleare e subnucleare
COMPASS is a fixed-target experiment that was put in operation in 2002 at CERN (SPS, M2 beamline). An important part of its physics programme is the exploration of the transverse structure of the nucleon via measurements of spin-(in)dependent azimuthal asymmetries in semi-inclusive DIS and, recently, also in Drell-Yan processes. Drell-Yan measurements with a $\pi^{-}$ beam interacting with a transversely polarized $NH_{3}$ target started with the 2015 run and will be continued in 2018. The measurement of the Sivers and other azimuthal asymmetries in polarized SIDIS and Drell-Yan performed by COMPASS provides a unique possibility to test (pseudo-)universal features of transverse-momentum--dependent parton distribution functions, predicted in QCD. Results of the first ever measurements of the polarized Drell-Yan reaction performed by COMPASS will be presented.