Session JA: Spin Physics

Overview of Spin physics at HERMES and COMPASS

The investigation of the partonic degrees of freedom beyond collinear approximation (3D description) has been gained increasing interest in the last decade. At the HERMES and COMPASS deep-inelastic-scattering experiment, several first measurements has been made which provide new insights on peculiar aspects of the parton dynamics within the nucleon or during fragmentation, i.e. related to spin-orbits effects. Complementary information has been gathered from spin-asymmetries in inclusive, semi-inclusive and exclusive channels. The two experiments feature a complementary energy regime, different beam and target set-ups and hadron identification in the final state to access flavor sensitivity. A compendium of the most interesting results will be presented.   

Nucleon Spin -- Results from Jefferson Lab

Over thirty years after the first experiments probed the spin structure of the nucleon, the pace of experimental and theoretical exploration of this subject keeps increasing. During its fifteen-year run with beam energies up to 6 GeV, Jefferson Lab has made many important contributions to this field - from measurements of the inclusive spin structure functions of the proton and the neutron over a wide kinematic range to seminal experiments accessing the three-dimensional nucleon spin structure through Generalized Parton Distributions and Transverse Momentum Dependent structure functions. An even brighter future lies ahead - after the 12 GeV upgrade, Jefferson Lab will completely map the spin-dependent parton distribution functions for all quark flavors in the valence region. In this talk, I will present an overview of this program, with special emphasis on recent and forthcoming results from the 6 GeV run and a glimpse of the future program with 12 GeV.   

Using Polarized Beams to Investigate the Spin of the Proton

The spin of the proton has been investigated with polarized beams and targets for decades and has led to our current picture of the kinematic and partonic structure of the proton's spin. Historically, this picture has relied heavily on data from Deep Inelastic Scattering of polarized leptons and is still mainly influenced by this framework. Over the past decade, operation of the RHIC/AGS has vastly increased the amount of data from collisions of polarized proton beams. Much theoretical and experimental work has been done to understand such probes as pions, jets, and Z/Ws especially with the STAR, PHENIX, BRAHMS, AnDY and pp2pp detectors. I will present an overview of the capabilities of the RHIC complex and demonstrate how measurements from many experiments are complementing and expanding our understanding of the proton spin.