The nucleon spin structure in a simple quark model
  We investigate the spin structure of the nucleon in an extended Jaffe-Lipkin quark model. In addition to the conventional $3q$ structure, different $(3q)(Q\bar{Q})$ admixtures in the nucleon wavefunction are also taken into account. The contributions to the nucleon spin from various components of the nucleon wavefunction are discussed. The effect due to the Melosh-Wigner rotation is also studied. 
Bo-Qiang Ma (Peking University, CCAST (World Laboratory), and Academia   Sinica, China), Ivan Schmidt (Universidad Tecnica F...