A narrow quasi-bound state of the DNN system

We have investigated a charmed system of DNN (composed of two nucleons and a D meson) by a complementary study with a variational calculation and a Faddeev calculation with fixed-center approximation (Faddeev-FCA). In the present study, we employ a DN potential based on a vector-meson exchange picture in which a resonant Λc(2595) is dynamically generated as a DN quasi-bound state, similarly to the Λ(1405) as a K¯N one in the strange sector. As a result of the study of variational calculation with an effective DN potential and three kinds of NN potentials, the DNN(Jπ=0−,I=1/2) is found to be a narrow quasi-bound state below Λc(2595)N threshold: total binding energy ∼225MeV and mesonic decay width ∼25MeV. On the other hand, the Jπ=1− state is considered to be a scattering state of Λc(2595) and a nucleon. These results are essentially supported by the Faddeev-FCA calculation. By the analysis of the variational wave function, we have found a unique structure in the DNN(Jπ=0−,I=1/2) such that the D meson stays around the center of the total system due to the heaviness of the D meson.