Border Country: Trannsverse Spin Observables as a Guide to Soft Processes in Chromodynamics
DW Sivers Co
The understanding of nuclear p[hysics and of soft hadronic processes requires reliable nonperturbative tools for QCD. Color confinement and the dynamic breaking of chiral symmetry strongly suggest that emergent structures will form the appropropriate quantum degrees of freedom for constructing such tools. Chiral perturbation theory and effective field theory (EFT) techniques based on lattice regularization provide examples of the strengths and limitations of our current approaches. Based on a result of Kane, Pumplin and Repko, KPR, we know that QCD perturbation theory for light quarks cannot generate transverse spin asymmetries, therefore it is possible to use transvers spin observables in hard-scattering processes to isolate coherent spin-orbit dynamics and view new aspects of soft QCD. A field strength description of an expanding sylindrical configuration of nonAbelian flux provides an example of this value of studying such observabls.