Quark-orbital Regge trajectories

It is shown that the pattern of Regge trajectories of hadrons becomes very much simpler and more regular than the usual Chew-Frautschi plot when one uses the orbital angular momentum of the quarks in a hadron instead of the spin of the meson and the spin minus 1/2 of the baryon, as the Reggeized angular momentum. Available data on particles and resonances are classified by means of the quark-orbital Regge trajectories, and as a result of it, the following pattern appears: there are linear rising quark-orbital trajectories with the universal slope for each irreducible representation of SU(6); actual hadron spectra are reproduced by adding the spin- and unitary spin-exchange interactions and the mass shift of the λ-quark. The Gell-Mann-Okubo mass formula holds rather good including resonances with high mass. Effects of the spin-orbit interaction are clearly recognized and its magnitude is nearly of the same order as those of the spin- and unitary spin-exchange interactions for mesons, whereas they are not so obvious for baryons. It follows from this splitting pattern of the quark-orbital Regge trajectories that the exchange degeneracies hold better for mesons than for baryons and that many "parity doublets" exist apparently and several parity partners should not appear, in conformity with experimental data. Classification of resonances using the orbital angular momentum between incoming two hadrons does not show much regularity. It is suggest from these results that strong interactions are essentially characterized by the degree of freedom of the spatial motion at the urbaryon level.