Abstract
The exploration of the transverse spin structure of the nucleon is one of the main topics of the COMPASS phase-II experiment. In 2015 and 2018 COMPASS performed Drell–Yan (DY) measurements using a 190 GeV \pmb{\pi^-}𝛑− beam interacting with a transversely polarized NH\pmb{_{3}}3 target and unpolarized W target. The azimuthal asymmetries in DY with transversely polarized NH_{3}3 target are sensitive to various transverse momentum dependent parton distribution functions. Preliminary results on the Sivers asymmetry are consistent with the QCD prediction for a sign-change of Sivers functions in DY. The angular coefficients \pmb{\lambda}𝛌, \pmb{\mu}𝛍 and \pmb{\nu}𝛎 that describe the unpolarized part of the DY cross section have been extracted from the data collected with W target. The preliminary results on the angular coefficients indicate the violation of the Lam–Tung relation, consistent with the observation in earlier DY experiments with pion beams.
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