Study On The ρ3(1990),Z(3930) And X(4160) States With Chiral Unitary Approach

In the recent years, a large number of new experiments in particle physics were carried out, and lots of new hadronic states were found. Theoretical study on the the nature of the new states has been done, which is a hot topic in hadron physics. The strong interaction can be well described at the region of high energy (or short distance). Due to the non-perturbative QCD effect at the lower energy region, one has to develop effective methods or models to study the strong interaction between hadrons. The chiral unitary approach is one of the effect methods that can describe well the masses, the widthes and the other properties of hadrons.In this thesis, the chiral unitary approach and local hidden gauge lagrangian are used to study the strong interaction between hadrons containing vector meson. Basing on the study of vector meson-vector meson two bodies scattering, the pK*K* three-body scattering with spin J= 3 is studied with the fixed-center approximation. The effects of various factors on the resulting quality (the mass and width of the resonant states) are investigated. Considering Z(3930) and X(4160) as vector meson-vector meson molecular states, the decays of Z(3930) and X(4160) to two final vector mesons are also studied, and the corresponding decay branching ratios are calculated.Briefly in fixed-center approximation we have a three-body system, as two parti-cles previously formed a group, and then the third particle scatter with the two-body group, so we can use the two-body scattering amplitude, and Faddeev equations to calculate the three-body scattering amplitude,this can simplifying the complex three-body scattering equations to solve for the two bodies. In our pK*K* systems scatter-ing, since ρK*K* scattering can form a two-body bound group f2’(1525) first, it is an IG(JPC)= 0+(2++) tensor meson resonances, and then vector meson ρ scatter with f2’(1525). Finally, it can form a IG(JPC)= 1+(3) resonances, In our calculations we found we have to take into account the vector meson width, and the two-body resonance’s (f2’(1525)) width, this will affect the final formation of the three-body res-onance, and finally we get a J= 3 dynamics generate resonance, we found with the quality and width which is very close with the p3(1990) in experiments, and all the quantum numbers fix well, so we think ρ3(1990) is likely to be a pK*K* resonance state.In the process of calculation of the two-body scattering we mainly reference to the L. S. Geng’s work. When we calculating the lowest order scattering kernel, we mainly consider interaction of four vector direct contact interaction, vector meson exchange t(u) channel contribution and box diagram contribution, in the process of deal with loop integrals diverge we took the dimensional regularization method, we introduced a renormalization constant-subtraction constant a(μ), which is the only free parameters in our calculation. We used the same parameters that L. S. Geng study light vector meson interactions, we take standard μ= 1000 MeV, subtraction constant α(μ)=-1.85.Next, we also study the structure of Z(3930) and X(4160), since Z(3930) and X(4160) were found in the experiment, there are a lot of possible structures discussed. E. Oset et al. used the chiral unitary approach to study the extended to SU(4) sym-metry vector meson-vector meson scattering, and then included D*D* vector meson and Ds*Ds*, which dynamics generated several resonances, they believe Z(3930) and X(4160) is D*D* and Ds*Ds* bound state. Basing on E. Oset’s research, we discuss the experiments generating vector meson ending state decay process. Our main image is considered experimental electron-positron(e+e-) collisions or γγ collision generates a pair of D*D* or Ds*Ds*, then D*D* or Ds*Ds* is formed resonances Z(3930) and X(4160) by the strong interaction, and finally Z(3930) and X(4160) decay to vector meson final states, we can calculate the decay branching ratio of this process, and then to give some theoretical predictions of experimental.