Particles, Astrophysics, and Nuclear Physics Seminar
In recent years parton distributions, describing longitudinal momentum, helicity and transversity distributions of quarks and gluons, have been generalized to account also for transverse degrees of freedom. Two new sets of more general distributions, Transverse Momentum Distributions (TMDs) and Generalized Parton Distributions (GPDs) were introduced to describe transverse momentum and space distributions of partons. Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs) in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs respectively. Facilities world-wide involved in studies of the 3D structure of the nucleon include HERMES at HERA, CLAS and Hall-A at JLab and COMPASS at CERN. Significant progress has been achieved recently in lattice measurements of TMD moments. Studies of TMDs and GPDs are also one of the main driving forces of the JLab 12 GeV upgrade project.
In this talk we present an overview of the latest developments in studies of TMDs and GPDs and discuss newly released results, ongoing activities, as well as some future measurements at JLab12.