The Study Of Light Meson Spectroscopy Based On The Observations From BES?

In recent years,more and more highly excited particles have been observed with the improvement of measuring precision and colliding energy at experiment.These include pseudoscalar mesons ?(2225),X(2100),X(2500),axial vector meson X(2100)observed in?'? invariant mass spectrum,and a structure around 2.2 GeV is observed in the process e+e-? KK.How to study their production and decay properties in the framework of light mesons has become an urgent research topic.In this work,we first systematically studied the highly excited pseudoscalar meson family.Stimulated by the BES? observation of ?(2100),X(2500)and ?(2225),we try to pin down new pseudoscalar meson nonets with these states.The mass spectrum anal-ysis and the Okubo-Zweig-Iizuka(OZI)-allowed two-body strong decay study using Regge trajectories and flux tube models indicate that X(2120)and ?(2225)associated ?(2070)and the predicate kaon K(2150)may form a new pseudoscalar meson nonet.And then,X(2500)with X(2370),?(2360)and the predicted kaon K(2414)can be grouped into another new pseudoscalar meson nonet.In addition,more experimental data for X(2100)are needed to determine its structure.Then,we noticed a higher mass pseudoscalar state in BES?'s recent experiment,which we thought might be a candidate state for ?(6S).This provides a good opportunity for us to study the pseudoscalar states of higher excited states.Therefore,we continue to study the properties of four ? states:?(6S),?(7S),?'(6S)and ?'(7S),expecting to provide valuable information for future experiments.Next,we focused on the structure denoted as X(2100)near 2.1 GeV in J/?????'decay.In this work,we assign X(2100)as the axial vector meson.With the help of Regge trajectory,we found that the X(2100)is a good candidate of the second radial excited state of h1(1380).In addition,we make use of flux-tube model to study the strong decay behavior of X(2100)under this assignment.The experimental width of the newly reported X(2100)can be reproduced in our calculation,which favors an assignment of X(2100)as the second radial excitation of h1(1380)with I(JP)=0(1+).And the B(X(2100)???')has a sizable contribution to the total width.However,we still need more experimental data to further confirm the assignment of X(2100)as h1(3P).Furthermore,we focus on the production of X(2100)and its flavour partner h1(1965)induced by pion and kaon on a proton target with the Feynman model and the Regge model,which is an available platform to further identify their nature.The numerical results indicate that the total cross section are similar in the two models.When the range of momentum PLab is 10 to 30 GeV/c,the total cross sections for ?-p?X(2100)n and K-p?X(2100)1 are predicted to be at an order of magnitude of 0.1 ?b.Whereas,the total cross section for?-p?h1(1965)n is near an order of magnitude of 10 ?b when PLab is from 10 to 30 GeV/c,and much larger than that of reaction K-p?h1(1965)A.These predictions can provide some valuable information to search for X(2100)and h1(1965)in experiments.In addition to BESIII,BABAR is also committed to studying the properties of lep-tons.The BABAR Collaboration indicated that there exists an explicit enhancement structure near 2.2 GeV when focusing on the e+e-??+?-process again,which inspires our interest in studying the production of higher p mesonic states.Since the branching ratios of ?+?-channel of D-wave ? states are much smaller than S-wave states,we choose ?(1900)and ?(2150)as the intermediate states in e+e-??+?-,where ?(1900)and p(2150)are treated as p(3S)and p(4S)states,respectively.Our result indicates that the BABAR's data of e+e-??+?-around 2 GeV can be depicted well,which shows that this enhancement structure near 2.2 GeV existing in e+e-??+?-can be due to the contribution from two ? mesons,?(1900)and p(2150).Additionally,this conclusion can be enforced by the consistence of the extracted values of ?e+e-B(?+?-)of ?(1900)and p(2150)in the whole fitting processes and the corresponding theoretical calculations.The present study of e+-??+?-data may provide valuable information to establish the p meson family.In combination with recent experimental observations,this Ph.D.dissertation focuses on the properties of the highly excited state of light mesons.This is of great significance for systematically understanding the family of light mesons and constructing a complete nonet.Simultaneously,our work is still very predictive,which will greatly guide and help future experiments in finding highly excited light mesons.