Orbital Angular Momentum in the Chiral Quark Model
  We developed a new and unified scheme for describing both quark spin and orbital angular momenta in symmetry-breaking chiral quark model. The loss of quark spin in the chiral splitting processes is compensated by the gain of the orbital angular momentum carried by quarks and antiquarks. The sum of both spin and orbital angular momenta carried by quarks and antiquarks is 1/2. The analytic and numerical results for the spin and orbital angular momenta carried by quarks and antiquarks in the nucleon are given. Extension to other octet and decuplet baryons is also presented. Possible modification and application are discussed. 
Xiaotong Song