Study of J/psi->phi K_s K_s in BESIII experiment

n this thesis, 1.3 billion of $J/\psi$ events collected by Beijing Electron Spectrometer (BES) III experiment have been analyzed. The decay channel of $J/\psi$ meson, $J/\psi\rightarrow\phi K_s K_s$, has been studied and the Dalitz plot has been produced. In the $K_{s}K_{s}$ invariant mass distribution, two peaks one at $\sim$ 1 GeV, and one at $\sim$ 1.5 GeV, which correspond presumably to the tetra-quark candidate $f_0(980)$, $f_2^{\prime}(1525)$ and/or glueball candidate $f_0(1500)$, respectively, has been observed. Another shoulder at 1.7 GeV has been observed and it is hypothesized to be $f_0(1710)$. Background studies showed that this channel is very selective and can be used to perform a detailed partial wave analysis, which will serve to confirm the results from earlier BESII data.