Study Of J/Ψ →η’h₁（1380）,E⁺e^-→ωη/ωπ⁰ And Inclusive π⁰/K_S⁰ At BESⅢ

The BESⅢ energy region resides at an overlap for both perturbative QCD and non-perturbative QCD,which makes it an ideal platform for testing the QCD mecha?nism.With study to quarkoniums φ(2170),p(2150)and axial-vector meson candidate h1(1380),this thesis discusses several calculations based on QCD model.We study the hadronic fragmentation functions through inclusive production measurements.Regarding h1(1380)as a 1P1ss axial-vector meson candidate has controversy on both theory and experiment.The precision measurements to mass and width are crucial to understand its nature.Using a sample of 1.31 ×109J/Ψ events,we report the ob-servation of J/Ψ→η’h1(1380).The mass and width of h1(1380)are M＝(1423.2±2.1±7.3)MeV/c2 and Γ=(90.3±9.8±1 7.5)MeV separately.Based on the measured mass,the mixing angle between the states h1(1170)and/h1(1380)is determined to be(35.9±2.6)°,which manifests the quark content of h1(1380)is ss.The isospin sym-metry violation is found by comparing the decay branching fractions of hl(1380)→K*(892)+K-+c.c.and h1(1380)→K*(892)0K0+c.c..The theorist explain the φ(2170)as conventional ss quarkonium,ssg hybrid,ssss tetraquark,AA bound state or final interaction from φf0(980)or φK+K-There are dis-crepancies for both measured mass and width ofφ(2170).The decay mode of φ(2170)is limited,especially no decay mode with non-strange final states.With total 651 pb-1 data at(?)= 2.00-3.08 GeV energy points,we measure the Born cross section of e+e-→ ωη and a resonant structure is observed with 6.56 statistical significance.The measured mass and width are M=2204±11±4MeV/c2 and Γ=81±25±5MeV separately.This resonant structure is consistent with 0(2170).Several ρ*resonances with JPC= 1--are recorded in PDG,e.g.,ρ(2000),p(2150),p(2250)and p(2270).These ρ*resonances are lack of experiment data or still remain controversial,especially for p(2150)whose mass and width have discrepancies at e+e-collision,pp collision and np scattering experiments.Considering the isospin of one ofωπ0,e+e-→ωπ0 is an ideal process to study p*resonances.With total 651 pb-1 data at(?)=2.00-3.08 GeV energy points,we measure the Born cross section of e+e-→ωπ0 and a resonant structure is observed with significance larger than 10σ.The mass and width are determined to be M=2046±19±7MeV/c2 and Γ=289±55±88MeV separately.According to the mass and width,this resonant structure is consistent with p(2150)or p(2000).The current data are not allowed to distinguish its physical nature.Inclusive production measurement is used to fit the fragmentation function.How-ever,for e+e-collision at 2-5 GeV,due to lacking of data and large statistical uncer-tainty,the inclusive production is not used for fragmentation function fit.BESIII ex-periment would decrease the theoretical uncertainty effectively.With 3.8 pb-1 data at(?)=2.80 GeV energy point,we perform the inclusive production of e+e-→KS0+X and e+e-→π0+X.The total uncertainty is better than 10%,which is about 1/5 of current uncertainty.