We study the branching ratios of D^＋ → D^0e^＋ν, Ds^＋ → D^0e^＋ν, Bs^0→B^＋e^-^-ν, Ds^＋→D^＋e^-e^＋ and Bs^0→B^0e^-e^＋ rare semileptonic decay processes, which are induced by decays of light quarks, the heavy quarks remain unchanged. The branching ratios of these decay processes are estimated in the heavy quark limit and with SU（3） flavor symmetry. We find that the decay rates are very tiny in the framework of the Standard Model. We also estimate the sensitivities of the measurements of these rare decays at the future experiments, such as BES-Ⅲ, super-B and LHC-b. Observations of these decays may shed some light on new physics beyond the standard model.
We reported the observation of Y（2175） in Фfo（980） mass spectrum in J/ψ → ηФfo（980） with fo（980） →π＋π^- and the observation of a broad 1^-- resonance of K^＋K^- mass in J/ψ→ K^＋K^-π^0. The results from the partial wave analyses of J/ψ→γπ^＋π^- and γπ^0π^0, as well as J/ψ →pK^-∧. are also presented.
The J/ψ hadronic decays provide good laboratory to search for the hybrid states with exotic quantum numbers. A full Partial Wave Analysis （PWA） is performed to the generated Monte Carlo J/ψ→ ρηπ data, based on the design of BESⅢ detector, to study the sensitivity of searching for a possible exotic state at BESⅢ.
We analyze the φ meson production in e^＋e^- →ωπ^0 as a probe for studying the isospin violation mechanisms. By clarifying the dynamic sources causing the isospin violation, we succeed in quantifying those mechanisms with the help of the recent KLOE data. Hence, the φ→ωπ^0 branching ratio is extracted. We find that apart from the electromagnetic （EM） transitions, the strong transition via intermediate kaon loops plays an important role in understanding the cross section and its lineshape.
In this proceeding, we propose to directly measure the a0^0（980）-f0 （980） mixing in J/ψ→φf0（980）→φa0^0（980） and Xc1→π^0a0^0（980） →π^0f0（980） with the upgraded Beijing Electron Positron Collider（BEPCII） with BESIII detector. We show that a narrow peak of about 8 MeV will be produced by the a0^0（980）-f0（980） mixing, and the predominant feature makes it standing out from the background contributions. The predicted branching ratios for these two reactions are both expected to be about O（10^-6）, which is unambiguously accessible with 10^9 J/ψ and 3 × 10^8 Xc1 at BESⅢ.
Decays of both η and η＇ provide very useful information in our understanding of low-energy QCD, and experimental signatures for these decays would be extremely helpful at BES-III. The rare decays of the η and η＇ mesons could serve as a low-energy test of the Standard Model and its beyond. The sensitivities of the measurements of η and η＇ decays are discussed at BES-III, in which the η and η＇ mesons are produced in the ψ decays.
The recent observations of the purely leptonic decay Ds＋→μ＋νμ and τ＋ντ at CLEO-c and B factory may allow a possible contribution from a charged Higgs boson. One such measurement of the decay constant fD. differs from the most precise unquenched lattice QCD calculation by a level of 4 σ. Meanwhile, the measured ratio, BR（Ds＋→μ＋νμ）/BR（D＋→μ＋νμ）, is larger than the standard model prediction at a 2.0σ level. We discuss that the precise measurement of the ratio BR（Ds＋→μ＋νμ）/BR（D＋→μ＋νμ） at BES-Ⅲ will shed light on the presence of new intermediate particles by comparing the data with the theoretical predictions, especially, the predictions of high precise unquenched lattice QCD calculations.
The CP violation in the D system is predicted to be an unobserved level in the Standard Model. In this paper, we describe the method of searching for CP violation decay processes with the coherently produced D^0D^0 mesons from the ψ（3770） decay. The CP violation decay processes can be searched for at the BES-Ⅲ experiment. The experimental sensitivity for searching for the CP violation can reach about a 10^-4 level with a ψ（3770） data sample of about 20 fb^-1.
The helicity amplitudes for Jψ→ ∧∧ and the relevant background decays are presented for measuring the ∧ decay parameter α ＋（∧ → pπ^＋） in J/ψ→ ∧∧. The Monte Carlo （MC） simulations based on the helicity amplitudes information are carried out. The likelihood fit method to determine the .∧ decay parameter is presented. Based on the MC generated sample, the sensitivity of the measurement for α＋ has been estimated, which shows that the J/ψ→ ∧∧ channel can be used to measure the .∧ decay parameter α＋（∧ → pπ^＋） well.
