Spin physics at COMPASS: present and future

The lecture discusses the COMPASS experiment at Cern performing deep inelastic scattering of polarised muons off polarised targets. The main results from the measurements performed since 2002 with longitudinal and transverse target polarisation are presented. The second part of the lecture discusses the plans and preparations for future measurements related to generalised parton distributions and transverse-momentum-dependent distribution functions. These experiments comprise deeply virtual Compton scattering as well as hard exclusive meson production in muon scattering off a liquid hydrogen target on the one hand and Drell–Yan dimuon production using a negative pion beam and a transversely polarised proton target on the other hand. During the GPD muon experiment, precise data will also be taken on hadron production and transverse-momentum-dependent distributions with the unpolarised proton target.