The Study Of Ditons With Heavy Quarks

Since Jaffe proposed the dibaryon H particle by using MIT pocket model in 1977 on the basis of symmetry,a lot of work has been done experimentally and theoretically to find this state.But up to now,people have not found this state.With the development of various theoretical methods,many possible dibaryon states have been proposed.But no dibaryon candidates have been confirmed experimentally until WASA experimental group reported a dibaryon resonance d*with I(JP)=O(3+)in the pn→dπ0π0 reaction.It was supported by theoretical calculation including one-boson-exchange model and chiral constituent quark models,and our group also predicted the existence of this pair of baryon states under the quark delocalization color screening model.Recently,WASA-at-COSY reported an isotensor dibaryon N△ with quantum numbers IJP=21+in the quasi-free pp→ppπ+π-reaction,and it motivated people to look for more dibaryons state.In recent years,many charmoniumlike and bottomoniumlike states so-called"XYZ" have been observed Such as X(3872),Y(4260),Zc(3900),Pc(4380)and Pc(4450)observed by the BABAR,Belle,BESIII and LHCb Collaborations.Some of these states are thought of as teraquark state and pentaquark state.And we’re going to think that it is easier to bind a multi-quark system with a heavy quark.For the system including heavy quarks,the large mass of quark reduces the kinetic energy of the system,making the system easier to bind.One may wonder whether exit the dibaryons with heavy quarks,and this topic is worth exploring.Much work has been done to look for the possible dibaryons with the heavy quarks.All of these theoretical studies tend to favor the existence of the dibaryons with the heavy quarks.Quantum chromodynamics(QCD)is widely accepted as a fundamental theory to study strong interaction.However,for hadron-hadron interactions and exotic quark states,it is difficult to use QCD directly to study low-energy hadronic interaction.Therefore,a vaxiety of quaxk models have been developed based on the theoretical method of QCD,which can successfully solve the problem of strong interaction between low and medium energy regions.The most widely used model is the chiral quark model,and the most representative one is the chiral quark model.It provides intermediate-range attraction mainly through the a meson exchange potential.But the existence of σ meson has not been determined.In the early 1990s,Wang fan et al from Nanjing University developed a new model of the quaxk delocalization color screening model(QDCSM)based on the traditional component quark model(Glashow-Isgur model).The intermediate-range attraction between hadronic and hadronic interactions is given by introducing the color screen effect and quaxk delocalization effect.And it has obtained some good results.This model has been well applied to describe the ground state baxyon spectrum and meson spectrum,study the AN and YN interactions,and predict the dibaryon candidates,such as d*,NΩ.The model also provides a reasonable explanation for the recently discovered pentaquark state with the heavy quarks.In addition,the model involves fewer parameters and has strong predictive power.Therefore,in this paper,we want to use this quark delocalization color screening model to farther study the dibaryons states with heavy quarks and find more possible dibaryons states.Based on the quark delocalization color screening model,the paper uses the reso-nance group method and the technique of fractional parentage expansion to calculate the six-quaxk system with heavy quarks systematically,and look for the possible dibaryons states or resonance states,provide reliable information for the experiment.Besides,the technique of fractional parentage expansion is unique to our group in the problem of pe-culiar hadronic state correlation.It is also an innovation for us to apply group theory to the calculation of physical correlation,we study the dibaryons with two heavy quarks of cc or bb with the strange S=0;the isospin I＝0,1,2 and the spin J=0,1,2,3 systematically in QDCSM.Our results show that there is two bound states of S wave in IJ=02 and/J=13,because its multi-channel coupling eigenvalue energy is lower than the minimum threshold of its multi-channel.The main ingredient of the bound state of TV=02 is NΞcc*and the bound energy is 4741 MeV·The main ingredient of the bound state of IJ=13 is ∑c*∑c*and the bound energy is 4969 MeV.In addition,the following resonance states can be found in our calculation:state of I J=00 at 4716 Mev,IJ=11 at 4757 Mev,IJ＝12 at 4949 MeV.The doubly-bottom dibaryons has properties similar to those of the doubly-charm dibaxyons,and there is also two bound states IJ=02 and IJ=13.The main ingredient of the bound state of IJ=02 is NΞbb*and the bound energy is 11416 MeV.The main ingredient of the bound state of IJ=13 is ∑b*∑b*and the bound energy is 11633 MeV.There might be resonance states at 11411 MeV of IJ=00,11437 MeV of IJ=11 and 11626 MeV of IJ=12.However,these conclusions are all our preliminary judgments on the energy calculation of the dibaryon states with two charm quarks and two bottom quarks at present.A more accurate conclusion needs to be determined by analyzing the properties of scattering phase shift and so on,and further research is also needed,which is our future work.