Probing transverse-spin-dependent nucleon structure in pion-induced dimuon production at COMPASS*

COMPASS is a fixed target experiment in the North Area of CERN with a broad physics program. One of its primary goals is to study the Transverse Momentum Dependent (TMD) Parton Distribution Functions (PDFs) that describe the substructure of nucleons. In 2015 and 2018 COMPASS recorded Drell-Yan (DY) and J/ψ events produced in the collisions of a 190 GeV/c negative pion beam with a transversely polarized proton target. Transverse-spin-dependent azimuthal asymmetries (TSAs) in the dimuon angular distributions of these collisions can be used to test the predicted sign change of the quark Sivers TMD PDF when measured in DY compared to semi-inclusive deep inelastic scattering. In addition, TSAs in J/ψ production may give access to gluon TMD PDFs and improve our understanding of the J/ψ production mechanism. Results from the analysis of 2015 and 2018 COMPASS data will be presented.