Drell-Yan measurements at the COMPASS experiment

Abstract

In 2015 and 2018 the COMPASS experiment at CERN measured muon-pair production in the Drell-Yan (DY) and J/Psi channels using a 190 GeV π− beam impinging on a transversely polarized NH3 and unpolarized nuclear targets (27Al, 184W). Apart from the absolute cross-section measurements for both processes, COMPASS studies also the target spin (in)dependent azimuthal asymmetries in both channels. Assuming the valence quark-antiquark annihilation to be the main production mechanism, one can interpret the azimuthal asymmetries in terms of convolutions of pion and proton Transverse Momentum Dependent (TMD) Parton Distribution Functions (PDFs). The TMD PDFs are universal QCD objects providing a mapping of parton densities in 3D momentum space. Recent results obtained by COMPASS for the DY and J/ψ channels will be discussed along with complementary semi-inclusive DIS (SIDIS) measurements and theoretical predictions.