Structure and reactions of pentaquark baryons

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In this research, we have investigated the structure and production/decay reactions of pentaquark baryons. We proposed an intuitive method to understand possible five quark structure of the pentaquarks using a conventional quark model. In this way we provided a view to understand the results of chiral quark soliton model. Also, we investigated how five quark structure affect various phenomena such as mass and decay width. In particular, we solved the five quark system precisely including bound as well as scattering states.In order to extract information of five quark structure from experiments, we investigated reaction mechanism. We consistently used an effective lagrangian method and determine model parameters from symmetries. Having spin and parity of the pentaquark states as unknown parameter, we predicted angular distributions and production rate of the reactions. In a proton-proton reaction, we proposed a method to determine the spin and parity of Theta+.As a related subject, we investigated properties of hyperon resonances, Lambda(1405) and Lambda(1520) having the strangeness-1 which is opposite to that of the Theta+. The former is know for some time to couple strongly to the anti-kaon and nucleon, and hence was regarded as another candidate of pentaquark states.