Interactions Between Zero-strangeness Baryon-baryon

In this thesis,we will continue to study the interactions of ΔΔ and NΔmulti-quark systems with all possible quantum numbers by using the resonant group method(RGM)in the framework of the chiral SU(3)quark model and the extended chiral SU(3)quark model.Firstly,we have dynamically studied the ΔΔ systems with all possible quantum numbers,and some interesting results are obtained.(1)The long-range interactions in the AA(3,0)and ΔΔ(0,3)systems are attractive,which mainly come from σ meson exchange.Further studies have indicated that such attractions can form bound states with 32-59MeV and 13-35MeV binding energies respectively both in the chiral SU(3)quark model and the extended chiral SU(3)quark model.The corresponding masse of ΔΔ(3,0)molecular state is about 2307-2431MeV,which is consistent with other theoretical results.It is possible to explain the experimental d*(2380)particles as a ΔΔ(3,0)molecular state.At the same time,the studies of the scattering phase shifts show that the S-wave ΔΔinteractions are attractions and the P-wave ΔΔ interactions are weakly attractive.There are nearly no interaction in the D-wave ΔΔ.(2)The ΔΔ(s,0)systems with the isospin I=0:The ΔΔ(1,0)and ΔΔ(2,0)systems have strong attractions in the long-range interactions by using the three sets of model parameters,which can form bound states with binding energies in a range of 11.9-89.1 MeV.Accordingly,the S-wave elastic scattering phase shifts give attractive trends.The long-range interaction in the ΔΔ(0,0)system is relatively strong attraction in the parameter Ⅰ,which mainly comes from the single gluon exchange potential.Therefore,ΔΔ(0,0)system can form a bound state with 65.2 MeV binding energy.However,ΔΔ(0,0)system mainly presents a strong repulsive force in the parameters Ⅱand Ⅲ,which can not form a bound state.The reason for the difference results is that the short-range mechanism in the two models is different.The one gluon exchange potential(OGE),which provides short-range force in the chiral SU(3)quark model(parameter Ⅰ),is strongly attractive,while the vector meson exchanges provide repulsive short-range forces in the extended chiral SU(3)quark model(parameters Ⅱand Ⅲ).We expect that the experiments can give the corresponding data to further determine which type of short-range mechanism is effective.S-wave scattering phase shifts of ΔΔ(S,0)systems give the same information as the previous interaction analysis.P waves are weakly attractive and D waves almost have no interaction.(3)Except for repulsive forces in the ΔΔ(2,2),ΔΔ(3,2),ΔΔ(2,3),and ΔΔ(3,3)systems,the medium-long-range interactions in systems with isospin I=1,I=2 and I=3 are attractive.The ΔΔ(0,1),ΔΔ(2,1),ΔΔ(3,1)and ΔΔ(0,2)systems can form bound states with 1.9-30.5MeV binding energies in the three sets of models parameters.The ΔΔ(1,1)and ΔΔ(1,2)systems only form weak bound states with 2.1MeV and 4.3MeV binding energies in parameterⅠ.The ΔΔ(1,3)system can form bound state with the binding energies 12.4MeV in parameters Ⅰ and 0.9MeV in Ⅲ,respectively.In all systems,the information from the S-wave scattering phase shifts is consistent with that from the analysis of the interactions and the bound states.The scattering phase shifts of the P waves indicate that there are weakly attractive force between ΔΔ and the D waves nearly have no effect.Then,the interactions in N Δ systems with spin S=2 and isospin I=1 or I=2 are studied dynamically.The results show that the NΔ(2,1)system with the isospin I=1 is weakly attractive in the three model parameters,which is not strong enough to form a bound state.The NΔ(2,2)system with the isospin I=2 is basically repulsive in the parameters Ⅱ and Ⅲ,and the long-range interaction is attractive in the parameterⅠ.Thus,it can form a bound state in parameter Ⅰ,and the binding energy is 7.9MeV.The results of NΔ(2,2)in the three sets of parameters are quite different because the repulsive forces from the vector mesons that provide the short-range force in parameters Ⅱ and Ⅲ are greater than the repulsion from the one gluon exchange that provide short-range force in parameter Ⅰ.In this thesis,it is possible to interpret d*(2380)as a ΔΔ(3,0)molecular state,and some bound states are predicted,as well.We expect further information from corresponding experiments on the interactions in ΔΔ and NΔ systems in order to check our theoretical results and the short-range mechanism between quarks.