Quantum Chromodynamics and Low Energy Effective Theory with Skyrmion.

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We have studied skyrmions which are soliton solutions of nonlinear sigma model as the low energy effective theory of the quantum chromodynamics (QCD). We also investigate relations between the chiral soliton model and the nonrelativistic quark model which plays important role to establish QCD and well reproduces the experimental data phenomenologically. Our main results of this research project are as follows :1. Topological properties of quantized chiral soliton on the 3-dimensional sphere are studied by introducing spin-isospin rotations and the breathing motion.2. On the basis of the skyrmion picture whether a consistent description of the pion-nucleon scatterings including higher order corrections has been a long-pending problem. Essential point of the problem is solved by this project.3. By changing the color degree of freedom N_C of QCD we studied the spin-flip baryon-vertex in the chiral soliton model as well as in the nonrelativistic quark model.4. An approach has started that takes into account of the quark degree of freedom which is not considered in the chiral soliton model.