Recent BES results on light scalars are reported in this talk, including the observation of a charged kappa decaying to K pi0 with 5.8 * 10^7 J/psi data at BES II and the direct measurements of a0(980)-f0(980) mixing in the processes J/psi --> phi f0(980) --> phi a0(980) --> phi eta pi0 and chi_c1 --> pi0 a0(980) --> pi0 f0(980) --> pi0 pi+ pi- with 2.26 * 10^8 J/psi data and 1.06 * 10^8 psi data at BES III.
Using samples of 2.25*10^8 J/psi events and 1.06*10^8 psi events collected with the BES III detector, we study the f0(980) to a0(980) and a0(980) to f0(980) transitions in the processes J/psi --> phi f0(980) --> phi a0(980) and chi_c1 --> pi^0 a0(980) --> pi^0 f0(980), respectively. Evidence for f0(980) --> a0(980) is found with a significance of 3.4 sigma, while in the case of a0(980) --> f0(980) transition, the significance is 1.9 sigma. Measurements and upper limits of both branching ratios and mixing intensities are determined.
This physics book provides detailed discussions on important topics in $tau$-charm physics that will be explored during the next few years at bes3 . Both theoretical and experimental issues are covered, including extensive reviews of recent theoretical developments and experimental techniques. Among the subjects covered are: innovations in Partial Wave Analysis (PWA), theoretical and experimental techniques for Dalitz-plot analyses, analysis tools to extract absolute branching fractions and measurements of decay constants, form factors, and CP-violation and DzDzb-oscillation parameters. Programs of QCD studies and near-threshold tau-lepton physics measurements are also discussed.
It is demonstrated that f_0-a_0 mixing can lead to a comparatively large isospin violation in the reactions pN -> da_0, pd -> ^3He/^3H a_0 and dd -> ^4He a_0 close to the corresponding production thresholds. The observation of such mixing effects is possible, e.g., by measuring the forward-backward asymmetry in the reaction pn -> d a_0^0 -> d eta pi^0.
We established a method on measuring the $dzdzb$ mixing parameter $y$ for BESIII experiment at the BEPCII $e^+e^-$ collider. In this method, the doubly tagged $psi(3770) to D^0 overline{D^0}$ events, with one $D$ decays to CP-eigenstates and the other $D$ decays semileptonically, are used to reconstruct the signals. Since this analysis requires good $e/pi$ separation, a likelihood approach, which combines the $dE/dx$, time of flight and the electromagnetic shower detectors information, is used for particle identification. We estimate the sensitivity of the measurement of $y$ to be 0.007 based on a $20fb^{-1}$ fully simulated MC sample.
Most recently, both BaBar and Belle experiments found evidences of neutral $D$ mixing. In this paper, we discuss the constraints on the strong phase difference in $D^0 to Kpi$ decay from the measurements of the mixing parameters, $y^prime$, $y_{CP}$ and $x$ at the $B$ factories. The sensitivity of the measurement of the mixing parameter $y$ is estimated in BES-III experiment at $psi(3770)$ peak. We also make an estimate on the measurements of the mixing rate $R_M$. Finally, the sensitivity of the strong phase difference at BES-III are obtained by using data near the $Dbar{D}$ threshold with CP tag technique at BES-III experiment.