Measurement Of E~+e~- �'ηJ/ψ Cross Section And Study Of J/ψ�'η’K(?)π At BESⅢ

In particle physics, the scientists have been working on hadron structrue and search-ing for new hadrons for many years to understand and consummate the Quantum Chro-modynamics (QCD), which is the theory of strong interactions. Except the conventional meson (consists of one quark and one anti-quark) and baryon (consists of three quarks), QCD also predicts the existence of glueball (gg), hybrids (qqg) and multiquark states. Charmonium physics provide an excellent laboratory for studying these new hadrons.Recent years, some new charmoniumlike states (also called the X, Y, Z particles) have been observed above the DD production threshold, such as X(3872)、X(3823)、 Y(4260)、Y(4360)、Y(4660)、Zc(3900)±/0、Zc(4020)±/0 and so on. Searching for new decay modes of these charmoniumlike states and measuring corresponding branch-ing fractions will shed light on the nature of these states. Using data samples collected with the BESⅢ detector at 17 center-of-mass energies from 3.810 to 4.600 GeV, we perform a stduy of haronic transition processes of e-e-�'ηJ/Ψ and e+e-�'π0J/Ψ. The Born cross sections of e+e-�'ηJ/Ψ are measured precisely at each center-of-mass energy; and by examining the e+e-�'ηJ/Ψ cross section as a function of center-of-mass energy, we find a enhancement around 4.200 GeV, which is similar with Belle’s results. This is the signal of haronic transition process of e+e-�'Ψ(4160)�'ηJ/Ψ. No obvious signal of e+e-�'Y(4260)�'ηJ/Ψ and e+e-�'Y(4360)�'ηJ/Ψ is observed; these results suggest that Y(4260) and Y(4360) are not conventional char-monium excitations, which will radiate a η to lower charmonia like the J/Ψ. In this analysis, no signal of iso-spin violation process of e+e-�'π0J/Ψ is observed; the upper limits at the 90% confidence level on the Born cross section are set.For the candidate of axial-vector strangeonium h1 (1380), its existence and precise-ly measured parameters are still needed in experiments. Using a world largest sample of (1310.6 ± 7) × 106 J/Ψ events collected with the BESⅢ detector, we study the pro-cesses of J/Ψ�'η’K+K-π0 and J/Ψ�'η’K±π(?). A clear structure around 1420 MeV/c2 is observed on the invariant mass of M(K+K-π0) and M(KS0K±π(?)). Fitting the structure with an S-wave relativistic Breit-Wigner lineshape gives a statistical sig-nificance exceeding ten standard deviations; and the mass and width of the structure are determined to be M= (1422±2±21) MeV/c2 and Γ= (88±9±24) MeV. Considering the mass location of this structure, the main decay mode to K*(892)K, the spin parity conservation and the angular distribution of η’ in the process of J/Ψ�' η’X(1420), this structure is identified as h1 (1380). In this analysis, the branching frac-tion of the production of h1 (1380) and its decays are also calculated:by η’K+K-π0 mode,B[J/Ψ�'η’h1(1380))×B(h1(1380)�'K*(892)-K-c.c.)=(1.53± 0.09±0.19]×10-4:by η’KS0K±π(?) mode.S(J/Ψ�'η1’h1(1380))×B(h1(1380)�' K*(892)K+c.c.)=(2.18±0.13±0.28)×10-4.Signincall isospin-breaking phe-nomenon (B(h1(1380)�'K*(892)+K-+c.c.)≠B(h1(1380)�'K*(892)0K0+ c.c.))is observed in B(h1(1380)�'K*(892)K+c.c.) processes between charged and neutral modes:and the dominanl reasons are from the nlass difierence between neutral K0/K0 and charged K±,neutral K*(892)0/K*(892).and charged K*(892)±. Also,the branching fractions of three body decays are measured:by η’K+K-π0 mod-e,B(J/Ψ�'η’K*(892)+K-c.c.)=(1.44±0.02±0.17)×10-3;by η’KS0K±π(?) mode,B[J/Ψ�'η’K*(892)+K-+c.c.)=(1.49±0.02±0.17)×10-3 and B(J/Ψ�' η’K*(892)0K0+c.c.)=(1.55±0.02±0.17)×10-3.In all measurenemts,trhe first uncertainties are statistical and the second are systematic.