Abstract:
The mass spectrum and magnetic moments of \Xi and \Omega baryon resonances are investigated in the bound state approach of the Skyrme model. The empirical hyperon spectrum shows that several hyperon resonances share a pattern of (approximately) equal mass spacings between the states of same spin but of opposite parity. It is found that this pattern can be explained mostly by the energy difference between the P-wave and S-wave kaons bound to the soliton. Although one cannot exclude the possibility that these states can be described as pion-hyperon resonances, the present approach predicts that \Xi(1620) and \Xi(1690) have J^P = 12^-, while \Xi(1950) has J^P = 12^+. The differences with the quark model predictions for the \Xi and \Omega baryon spectrum are pointed out. Several relations for the masses and magnetic moments of those resonances are also obtained.

Abstract:
Understanding strong interactions at low energy region requires the precise knowledge on the spectra and the properties of hadrons. Such informations can be obtained through detailed and sophisticated analyses of experimental data collected from various scattering processes using electromagnetic beams or hadron beams. At present, there have been a lot of precise data collected for the production of meson-baryon final states in photon-nucleon and nucleon-nucleon scattering processes. Since the total centerof- mass energy range of such scattering experiments covers the resonance region of about 2 GeV, it is legitimate to include as many baryon resonances as possible in the analyses of the data, which requires the formalism to describe high-spin baryon resonances. Here, we use the Fronsdal method to describe high-spin baryon resonances and develop their interaction Lagrangians. We then apply this method to investigate the role of high-spin baryon resonances in the reactions of γp → KΣ(1385) and γp → K+K+Ξ .

Abstract:
In spite of the early efforts for studying Ξ resonances, we still do not have enough information on the properties of these resonances. The number of observed Ξ resonances is much smaller than the quark model predictions, and the predicted mass spectrum shows serious model-dependence. Furthermore, the spin-parity quantum numbers are not known for most observed resonances and the parity of the ground state Ξ has never been measured. In this talk, we review the issue in the Ξ spectrum and present a model for Ξ photoproduction which emphasizes the role of high-spin hyperon resonances.

Abstract:
The polarization observables in phi photoproduction are suggested for probing the nucleon strangeness. Based on models for phi photoproduction, some double polarization observables are shown to be very sensitive to the strangeness content of the proton because of the different spin structures of the amplitudes associated with different mechanisms.

Abstract:
The electric quadrupole moments of the decuplet baryons are calculated in the bound state approach of the Skyrme model. In this approach, all the quadrupole moments of the decuplets are found to be proportional to the third component of the baryon isospin. Contrary to the SU(3) collective model, the kaonic contribution is as important as the pionic one. The transitional quadrupole moments of the hyperons are also predicted.

Abstract:
The mass spectrum and magnetic moments of \Xi and \Omega baryon resonances are investigated in the bound state approach of the Skyrme model. The empirical hyperon spectrum shows that several hyperon resonances share a pattern of (approximately) equal mass spacings between the states of same spin but of opposite parity. It is found that this pattern can be explained mostly by the energy difference between the P-wave and S-wave kaons bound to the soliton. Although one cannot exclude the possibility that these states can be described as pion-hyperon resonances, the present approach predicts that \Xi(1620) and \Xi(1690) have J^P = 12^-, while \Xi(1950) has J^P = 12^+. The differences with the quark model predictions for the \Xi and \Omega baryon spectrum are pointed out. Several relations for the masses and magnetic moments of those resonances are also obtained.

Abstract:
We discuss the photoproduction processes of light vector mesons ($\rho$, $\omega$, and $\phi$) from the nucleon near threshold. We first develop a simple model based on meson exchanges which is modified by the nucleon pole terms. We then extend this model to study other physically interesting topics. As examples, we discuss the missing nucleon resonances problem in $\omega$ photoproduction and the direct $\phi NN$ coupling constant in $\phi$ photoproduction. The calculated cross sections are compared with the recent experimental data. Various spin observables are discussed, which may be measured at current photon/electron facilities such as TJNAF and SPring-8 of RCNP. Precise measurements of such quantities would provide very useful information to understand the production mechanism.

Abstract:
The low mass of the $\Lambda(1405)$ hyperon with $j^P = 1/2^-$, which is higher than the ground state $\Lambda(1116)$ mass by 290 MeV, is difficult to understand in quark models. We analyze the hyperon spectrum in the bound state approach of the Skyrme model that successfully describes both the $\Lambda(1116)$ and the $\Lambda(1405)$. This model predicts that several hyperon resonances of the same spin but with opposite parity form parity doublets that have a mass difference of around 300 MeV, which is indeed realized in the observed hyperon spectrum. Furthermore, the existence of the $\Xi(1620)$ and the $\Xi(1690)$ of $j^P=1/2^-$ is predicted by this model. Comments on the $\Omega$ baryons and heavy quark baryons are made as well.

Abstract:
In order to develop a model that can describe both a single baryon and multi-baryon systems on the same footing, we re-investigate the Skyrme model in a chiral Lagrangian derived from the hidden local symmetry (HLS) up to $O(p^4)$ including the homogeneous Wess-Zumino terms. We use the master formulas that connect the parameters of the HLS Lagrangian and a class of holographic QCD models, which provides a controllable way to determine the low-energy constants of the Lagrangian once the pion decay constant and the vector meson mass are given. Therefore, this model allows us to study the role of vector mesons in the skyrmion structure. We find that the $\rho$ and $\omega$ vector mesons have different roles in the skyrmion structure and that the $\omega$ meson has an important role in the properties of the nucleon.

Abstract:
The reactions of $K \Sigma(1385)$ photoproduction, i.e., $\gamma p \to K^+ \Sigma^0(1385)$ and $\gamma n \to K^+ \Sigma^-(1385)$, are investigated in the resonance energy region for studying the role of the nucleon and $\Delta$ resonances of masses around 2 GeV. The Lagrangians for describing the decays of these resonances into the $K \Sigma(1385)$ channel are constructed and the decay amplitudes are obtained, which allows us to determine the coupling constants using the predictions of quark models or the data listed by the Particle Data Group. The resulting cross sections are compared to the data from the Thomas Jefferson National Accelerator Facility and the SPring-8, which indicates nontrivial contributions from the two-star-rated resonances in the Particle Data Group as well as from some missing resonances predicted by a quark model.