The pseudoscalar meson and baryon octet interaction with strangeness S = −2 in the unitary coupled-channel approximation

Abstract

Abstract The interaction of the pseudoscalar meson and the baryon octet with strangeness S = − 2 and isospin I = 1 / 2 is investigated by solving the Bethe–Salpeter equation in the infinite and finite volume respectively. It is found that there is a resonance state generated dynamically, which owns a mass of about 1550 MeV and a large decay width of 120–200 MeV. This resonance state couples strongly to the π Ξ channel. Therefore, it might not correspond to the Ξ ( 1620 ) particle announced by Belle collaboration. At the same time, this problem is studied in the finite volume, and an energy level at 1570 MeV is obtained, which is between the π Ξ and K ¯ Λ thresholds and independent of the cubic box size.