Mass Levels and Decay Probabilities of Nucleon Resonances : An Analysis Based on the Independent Particle Like Model

概要

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It has been shown that the presently known data on baryons (isospin, spin, parity and mass) can be understood fairly well by the composite model of three fundamental triplets (fermions) of SU_3 under a certain number of simple assumptions. From the same point of view as a previous paper, the following results are obtained: (i) By assuming that three fundamental fermions in the baryon behave nonrelativistically as independent particles in the effective mean potential (square well like) with the depth ~10 BeV, the potential range (~1 BeV^<-1>) is determined and energy levels of nucleon resonances are obtained. A slightly modified square well potential leads to excellent agreement with observed mass levels of nucleon resonances. (ii) Decay probabilities of N^*_J→N+π processes are obtained by taking account of the effect of our model from the point interaction Lagrangian among the N^*_J, N and π fields. As a result we determine two universal coupling constants corresponding to resonances with the different intrinsic spin connected with a relation g^2_<1/2>=20g^2_<3/2>. It is shown that the observation of 2s-, 2p- and 2d- levels suggested from our model is difficult. (iii) In order to estimate the effect of our model, as an extreme case, calculation of N^*_J→N+π decay probabilities is carried out by using a method similar to a multipole transition from the nucleus.
理論物理学刊行会の論文
1967-02-25