Spin-orbit interactions between two baryons

The spin-orbit interactions in the quark cluster models are reviewed in this article. The observed spin-orbit force between two nucleons is strong, while that in the excited baryons or in the ΛN interaction is small. We try to sort out whether the quark cluster model can produce a spin-orbit force which explains these features simultaneously. Various works which include the spin-orbit force with different origins such as gluons, mesons, or coupling to other channels are compared to each other. The roles of the symmetric and anti-symmetric spin- orbit forces in the NN scattering phase shifts and in the YN low-energy cross sections and the phase shifts are investigated. (author)