Using a sample of 225.3 million $jpsi$ events collected with the BESIII detector at the BEPCII $e^+e^-$ collider in 2009, searches for the decays of $eta$ and $eta^primetopi^+ e^- bar{ u}_e +c.c.$ in $jpsi to phi eta$ and $phieta^prime$ are performed
. The $phi$ signals, which are reconstructed in $K^+K^-$ final states, are used to tag $eta$ and $eta^prime$ semileptonic decays. No signals are observed for either $eta$ or $eta^prime$, and upper limits at the 90% confidence level are determined to be $7.3times 10^{-4}$ and $5.0times 10^{-4}$ for the ratios $frac{{mathcal B}(etato pi^+ e^- bar{ u}_e +c.c.)}{{mathcal B}(eta to pippimpiz)}$ and $frac{{mathcal B}(eta^primeto pi^+ e^-bar{ u}_e +c.c.)}{{mathcal B}(eta^prime to pippimeta)}$, respectively. These are the first upper limit values determined for $eta$ and $eta^prime$ semileptonic weak decays.
Using a sample of $(225.3pm 2.8)times 10^{6}$ $J/psi$ decays collected with the BESIII detector at BEPCII, searches for invisible decays of $eta$ and $eta^prime$ in $J/psitophieta$ and $phieta^prime$ are performed. Decays of $phi to K^{+}K^{-}$ are u
sed to tag the $eta$ and $eta^prime$ decays. No signals above background are found for the invisible decays, and upper limits at the 90% confidence level are determined to be $2.58times10^{-4}$ for the ratio $frac{mathcal{B}(etatorm{invisible})}{mathcal{B}(etatogammagamma)}$ and $2.39times10^{-2}$ for $frac{mathcal{B}(eta^primetorm{invisible})}{mathcal{B}(eta^prime togammagamma)}$.
Using a sample of $(225.2pm 2.8)times 10^6$ $J/psi$ events collected with the BESIII detector, we present results of a study of $J/psirightarrow gammaLambdabar{Lambda}$ and report the first observation of the isospin violating decay $J/psirightarrowL
ambdabar{Sigma}^{0}+c.c.$, in which $bar{Sigma}^{0}$ decays to $gamma bar{Lambda}$. The measured branching fractions are $mathcal{B}(J/psirightarrowbar{Lambda}Sigma^{0}$) = $(1.46pm0.11pm0.12) times10^{-5}$ and $mathcal{B}(J/psirightarrowLambdabar{Sigma^{0}}$) = $(1.37pm0.12pm0.11) times10^{-5}$. We search for $Lambda(1520) rightarrow gamma Lambda$ decay, and find no evident signal, and an upper limit for the product branching fraction $mathcal{B}(J/psirightarrowLambdabar{Lambda}(1520)+c.c.)times mathcal{B}(Lambda(1520)rightarrowgammaLambda)<4.1 times10^{-6}$ is set at the 90% confidence level. We also report the observation of $eta_{c}rightarrowLambdabar{Lambda}$ in $J/psi rightarrow gamma eta_{c}$, $eta_{c}rightarrowLambdabar{Lambda}$ and measure the branching fraction $mathcal{B}(eta_{c}rightarrowLambdabar{Lambda}) =(1.16pm0.12 (stat)pm0.19(syst)pm0.28(PDG))times10^{-3}$.
The recent observations of the purely leptonic decay $Ds to mu^+ u_{mu}$ and $tau^+ u_{tau}$ at CLEO-c and $B$ factory may allow a possible contribution from a charged Higgs boson. One such measurement of the decay constant $f_{D_s}$ differs from th
e most precise unquenched lattice QCD calculation by 4 $sigma$ level. Meanwhile, the measured ratio, ${cal BR}(Ds to mu^+ u_{mu})$ / ${cal BR}(Dp to mu^+ u_{mu})$, is larger than the standard model prediction at 2.0$sigma$ level. We discuss that the precise measurement of the ratio ${cal BR}(Ds to mu^+ u_{mu})$ / ${cal BR}(Dp to mu^+ u_{mu})$ at BES-III will shed light on the presence of new intermediate particles by comparing the theoretical predictions, especially, the predictions of high precise unquenched lattice QCD calculation.
In this paper, we calculate the decay rates of $D^+ to D^0 e^+ u$, $D^+_S to D^0 e^+ u$, $B^0_S to B^+ e^- bar{ u}$, $D^+_S to D^+ e^- e^+$ and $B^0_S to B^0 e^-e^+$ semileptonic decay processes, in which only the light quarks decay, while the heav
y flavors remain unchanged. The branching ratios of these decay processes are calculated with the flavor SU(3) symmetry. The uncertainties are estimated by considering the SU(3) breaking effect. 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-$b$.
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 theoretic
al 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.
This paper presents the results of searches for the flavor-changing neutral current, lepton-number-violating and lepton-flavor-violating processes in the charm mesons decays. Recent results from charged $D$ mesons decays to final states with dielectr
ons from CLEO-c are reported. The prospects of the searches for the rare charm decays at BES-III are also discussed.
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.
