We present physics opportunities and topics with the ss states （strangeonia） that can be studied with the BESⅢ detector operating at the BEPCⅡ collider. Though the dp and η/ηt states have long been established experimentally, only a handful of strangeonia are well known, in contrast to the rich cc charmoium system. An overview of the ss states and their experimental status is presented in this paper. The BESⅢ experiment has collected the world＇s largest samples of J/ψ, ψ（2S）, ψ（3770）, and direct e＋e- annihilations at energies below the J/O and above 3.8 GeV, and will continue to accumulate high quality, large integrated luminosity in the T-charm energy region. These data, combined with the excellent performance of the BESⅢ detector, will offer unprecedented opportunities to explore the ss system. In this paper we describe the experimental techniques to explore strangeonia with the BESⅢ detector.
Study of the rare and forbidden decays of η/η offers a sensitive probe to test fundamental symmetries of quantum chromodynamics and search for new physics beyond the Standard Model. To study the rare decays of η/η to π ＋ π - e ＋ e - , π ＋ π - μ ＋ μ - and e ＋ e - μ ＋ μ - at the BES detector, we developed several event generators based on the vector meson dominant model with finite-width corrections and the pseudoscalar mesons mixing theory. The various distributions from event generators are in good agreement with the theoretical predictions, which indicates that the event generators work very well after implemention in the BES Monte Carlo simulation package. In the BES physics analysis, the performance of the event generators will be improved in accordance with the distributions of different variables of η/η from data and the improvement on the theoretical calculations.
