$\Theta^+ $ baryon, $ N^*(1685) $ resonance, and $\pi N $ sigma term in the context of the LEPS and DIANA experiments

摘要: We reexamine properties of the baryon antidecuplet and , and the sigma term within the framework of a chiral soliton model, focusing on their dependence on the mass. It turns out that the measured value of the mass, MeV, is consistent with that of the mass MeV by the LEPS collaboration. The magnetic transition moments are almost independent of the mass. The ratio of the radiative decay width to turns out to be around 5. The decay width for is studied in the context of the LEPS and DIANA experiments. When the LEPS value of the mass is employed, we obtain MeV. The sigma term is found to be almost independent of the mass. In addition, we derive a new expression for the sigma term in terms of the isospin mass splittings of the hyperon octet as well as that of the antidecuplet .