Spin structure of the nucleon: current status and future measurements

The quark-gluon dynamics manifests itself in a set of non-perturbative functions  describing all possible  spin-spin and spin-orbit correlations. Recent studies of correlated hadron pairs,  including the pairs created in target and current fragmentation region, indicate significant correlations in hadron fragmentation process. Their understanding is becoming increasingly important in the interpretation of pion electroproduction data in general, and hadronization process of quarks, in particular. Detailed studies in multi-dimensional space, of various multiplicities and different azimuthal modulations in electroproduction of hadrons as a function of transverse momentum of involved hadrons and the Q^2, will be needed to sort out all disagreements with theory predictions and improve the phenomenology of partonic distributions in 3D.

In this contribution, we will present ongoing studies and some proposed future measurements with hadrons in electroproduction at large Q^2,  with current CLAS12 detector at Jefferson Lab, and discuss opportunities with JLab energy upgrade to 24 GeV.