The Production And Decay Of Hadron States In The Phenomenological Models

In the last decades,there are lots of studies on the structure and the spectra of the hadron states,from both the experimental and theoretical points of view,respectively.In addition of the mesons and baryons predicted by the conventional quark model,there are some exotic states,such as molecular states,hybrid states,multi-quark states,glueballs,etc.More and more exotic states have been reported in experiments,the structure and the spectra of the hadron states has become the two of improtant issues in hadron physics,and there are abundant theoretical studies about the hadron spectroscopy,however,there are still some problems on the theoretical studies.Firstly,there are still some states,which cannot be accommodated in the conventional quark model,and need to be explained in other ways.Secondly,the properties of hadrons are subject to the behaviors of the Quantum Chromodynamics(QCD)in the low-energy non-perturbative regime,which cannot be precisely calculated within the perturbative methods,and we need the phenomenological models to invesigate the properties of hadrons.Thirdly,the theoretical results given by the phenomenological models are model-dependence,and could be different for different models.Considering the less precise experimental data for some processes,it is difficult to presicely understant the properties and structures of hadrons theoretically.During the last four years,we have implemented the studies of the structures and properties of hadron states within phenomenological models,and given some predictions,which could be helpful to understand the properties of the QCD in the low-energy non-perturbative regime.Our project consists of three topics.(1)We have investigated the photoproduction reaction ?p?f1(1285)p within an effective Lagrangian and Regge model,and taken into account the contribution of s-channel N(2300).Combining with the CLAS Collaboration data,we have fit the CLAS data of differential cross section of the reaction ?p?f1(1285)p in twice,Fit A including the contributions of N(2300)and Fit B excluding N(2300),respectively.The?2/dof of both are 1.05 and 1.89.We have calculated the total cross section and differential cross sections of the reaction ?p?f1(1285)p compared with the CLAS data.The results show that Fit A can better describe the experimental data than Fit B.Finally,we present the total cross section of ?p?f1(285)preaction with and without N(2300).It can be seen there is a clear peak structure with the magnitude of order 80 nb,which is not found in Fit B.Thus,we suggest that this reaction can be used to serach and study the nucleon resoances N(2300),and can be used to test our model.(2)Within an effective Lagrangian approach,we have studied the charmed baryon production reaction (?)?(?),and explored the possible contribution of Y(4630).Besides the t-channel D and D*meson exchanges,the s-channel charmoniumlike Y(4630)state exchange is taken into account in our model.Because the experimental data of Y(4630)? pp is scarce,we compute the coupling constants.And we calculate the total cross sections and differential cross sections of (?)�(?) reaction.Our calculations show that the contribution of s-channel Y(4630)intermediate state plays an important dominant role near the threshold,and gives a clear peak structure of the magnitude of 10 ?b at the center-of-mass energy 4.63 GeV in total cross section of the reaction (?)?(?).Hence,this reaction provides a new good platform to search and study the charmoniumlike Y(4630)state and XYZ.(3)We have evaluated the spectroscopy of higher pesudoscalar and vector charmonium states in the relativistic quark model.Taking into account that the assignments of these states are not determined by the mass alone,we have investigated the strong decay properties in the 3P0 model employing the realistic wave functions from the relativistic quark model.Our calculations show that some of charmonium states can be reasonably explained in the conventional qq picture.We suggest that the X(3900),?(4040),X(4230),?(4160)can be interpreted as the?c(31S0),33S1,43 S1 and 23 D1 cc states,respectively.X(4160)and X(4260)can not be explained within traditional quark model.?(4415)may be 43S1 or 33 D1;X(4660)may be 53 S1 or 43 D1.These properties need more information to be confirmed.