The Interaction Between Nucleus N And D Meson Was Studied Under The Component Quark Model

The exploration of nucleon-meson interactions at quark level is an important topic of the strong interaction physics. It is we-known that the quantum chromodynamics (QCD) is the fundamental theory of the strong interaction. On the basis of properties of asymptotic freedom of QCD, the coupling constant decreases with the increasing energy, the accurate solution can be obtained by perturbation method in the high energy region of the quark-gluon systems. However, the coupling constant will become large for the low-energy systems which the most hadrons belong to, the perturbation theory can no longer be applied. The non-perturbation method is required to deal with the properties of hadron, hadron-hadron interaction, multiquark systems and so no. One of the important aspect in this region is to establish the phenomenological models on the basis of QCD.Besides the lattice QCD, the method to study the quark-gluon system from the first principle, the main QCD phenomenological models currently are constituent quark model, MIT bag model, soliton model, QCD sum rules, etc. The validation of these models depends on the correct description of the experimental data. The structure and interactions of the hadrons are the ideal field to test those models. The most convenient and most used model is the constituent quark model. The typical one of the constituent quark model is the chiral quark model (ChQM). By bringing in the chiral symmetry at the quark level and taking into account of the spontaneous symmetry breaking of the chiral symmetry, the current quarks turn into the constituent quarks and the coupling between quark and chiral field is introduced. In this way, the chiral SU (2) linear a model is setup for two-flavor quark systems. Fernandez and other scientists have used the model to give a successful description of the non-strange two-flavor quark systems. Zhang Zongye and her collaborators extends the model to SU(3) and obtained a good description of u, d, s three-flavor systems. In 1990s, F. Wang of Nanjing University and his collaborators developed a new kind of phenomenological quark model, named quark delocalization color screening model (QDCSM), based on the conventional constituent quark model (Glashow-Isgur model). As for single hadron, it is just the Glashow-Isgur model, which describes the properties of hadrons well. For the two-nucleon systems, it also obtains the intermediate attraction without invoking the σ meson exchange. In this model, the multi-body properties among quarks are considered, and it is realized by supposing the quark-quark interaction relying on the states they occupied, and the hidden-color effect is imitated by introducing the screened color confinement. Another feature of the model is that the multi-quark system is allowed to choose its own suitable configuration by dynamics, which is realized by varying the delocalization parameter according to the energy of the system. Because the model itself has few parameters, it has very strong predictive power. It has been applied to study the baryon-baryon interactions, multi-quark system and so on. A good agreement with experimental data is achieved.Charmed baryon Ac(2940) was reported by BABAR collaboration in 2007 and it was confirmed by Belle collaboration. The state was proposed to be a molecule state of D*N, because of its mass is close to the threshold of D*p. Some research showed that the three-quark nature was also possible. Σc(2800), which was reported by Belle and BABAR collaborations, is another molecule state candidate of DN. In this work, Salamanca chiral quark model an QDCSM are employed to study systematically the properties of DN systems. The aim is to explore the possibility of assigning Λc(2940) and Σc(2800) as the molecular states of D*N and DN. The procedure of the study is as follows. First, the model parameters are determined by fitting the spectrum of nucleon and D-meson. Then the effect potentials between nucleon and D meson are obtained in the adiabatic approximation. The effective attraction between nucleon and D-meson is the necessary condition for the forming of bound-state or resonance. Then, the possible channels of forming bound-state or resonance are located by analyzing the effective potentials. At last, the dynamical calculation is performed in the framework of resonating-group method for these channels. The results show that the chiral quark model and QDCSM give similar results. ΛC(2940) can be explained as D*N molecular state and Σc(2800) cannot be identified as molecular state. There are also several other resonance states predicted. The experimental search is expected.