Session H04: Hadronic Spin Structure

Live

Experimental results sensitive to the spin structure of the nucleon and nuclei are presented. The shown results cover measurements of deep-inelastic scattering in lepton-hadron interactions as well as exclusive processes in hadron-hadron collisions. The way in which the various processes access different aspects of the spin structure is introduced and the theoretical interpretation of the measurements is clarified.   

Live

One of the crucial properties of the strong force is confinement, the fact that quarks and gluons do not exist as free particles. As a consequence, any parton struck in a high-energy scattering process and extracted from its parent hadron must hadronize, namely it is dynamically converted into hadrons. In this talk I will briefly overview the physics of hadronization encoded in single hadron, di-hadron, and jet fragmentation functions, together with their potential to enable the study of specific properties of nucleon structure in semi-inclusive processes. For each of the three categories of fragmentation functions, I will provide an example of their interplay with specific projections of hadron structure in momentum space.   

Live

The Relativistic Heavy-Ion Collider (RHIC) is a unique facility. It is the world's only polarized proton + proton collider capable of delivering highly polarized protons up to a center-of-mass energy of 510 GeV. Polarized proton + proton collisions allow one to study the proton's spin structure using strong interactions by measuring single and double spin asymmetries. Using longitudinally polarized protons, the STAR experiment at RHIC can probe the proton's longitudinal spin structure, providing insights into the proton's parton helicity distributions. Employing transversely polarized proton collisions, STAR can study the transverse spin structure of the proton and properties of QCD through transverse spin effects. Presented here is a summary of recent STAR results and how they play a crucial role in understanding the proton spin structure. Moving beyond 2021, an outlook will also be presented of future measurements exploiting the STAR forward upgrade.