Baryon resonances in the baryon meson scattering coupled to the q³-state

¹ Japan College of Social Work, Kiyose, Tokyo 204-8555, Japan
² Department of Physics, Sophia University, Kioi, Chiyoda, Tokyo 102-8554, Japan

^a e-mail: s.takeuchi@jcsw.ac.jp

Abstract

We investigate Λ(1405), ∆(1232), and N* (1440) as resonances in the baryon-meson scattering with bound states embedded in the continuum (BSEC). This BSEC is introduced by hand, as a state not originated from a simple baryon-meson system. We assume it comes from the three-quark state. The resonances are successfully reproduced by this scheme. As for the Λ(1405) resonance, it is found that our calculation can give an appropriate energy and width for the peak and reproduces the scattering length when the BSEC contribution to the resonance is roughly half of that of the channel. The energy of the three-quark pole for ∆(1232) is taken to be 1327 MeV, which comes down to 1232 MeV after the mixing to the Nπ and ∆π scattering states is included. The nucleon also gets the self energy of about 130 MeV, so the N∆ mass difference, which is one of the key values in the quark model, does not change much. It also found that the positive parity excited nucleon mass can be reduced by more than 400 MeV and become around 1440 MeV after the mixing to the continuum is taken into account.