Search

The negative-parity charmed baryons are investigated by employing the quark model as well as the effective baryon meson model with a bound state embedded in the continuum. Especially the mass difference between the JP = 1/2- and 3/2-Λc+ baryons is discussed. The observed value of this mass splitting is almost the same as that of Ξc, about 30 MeV. It is found that most of this splitting can be reproduced by assuming a simple qqQ configuration. The coupling to the baryon-meson scattering state may enlarge the splitting as it does for the Λ(1405)(1/2-) and Λ(1520)(3/2-) case. We investigate this coupling effect and find that with an appropriately modified coupling or the pole energy, the peak can be reproduced. [ABSTRACT FROM AUTHOR]

We investigate the excited baryons and mesons which cannot be described in terms of a simple constituent quark model, such as Λ(1405) and X(3872) as a resonance in a coupled channel hadron-hadron (baryon-meson or meson-meson) scattering with a 'bound state embedded in the continuum' (BSEC). For this purpose, we solve the Lippmann-Schwinger equation including a BSEC in the momentum space. This BSEC is introduced by hand, as a state not originated from a simple baryon-meson or meson-meson system. We assume it comes from the three-quark state or quark-anti quark state and show such a picture can describe the Λ(1405) and X(3872) resonances. [ABSTRACT FROM AUTHOR]