The Transformation from Translucent into Transparent Rare Earth Ions Doped Oxyfluoride Glass-Ceramics with Enhanced Luminescence

Article reporting a scenario where a translucent Er3+−Yb3+ doped oxyfluoride precursor glass-ceramic (P-GC) becomes transparent with increasing crystal size and crystallinity

Direct Measurements of the Branching Fractions for D0→K−e+νeD^0 \to K^-e^+\nu_e and D0→π−e+νeD^0 \to \pi^-e^+\nu_e and Determinations of the Form Factors f+K(0)f_{+}^{K}(0) and f+π(0)f^{\pi}_{+}(0)

The absolute branching fractions for the decays $D^0 \to K^-e ^+\nu_e$ and $D^0 \to \pi^-e^+\nu_e$ are determined using $7584\pm 198 \pm 341$ singly tagged $\bar D^0$ sample from the data collected around 3.773 GeV with the BES-II detector at the BEPC. In the system recoiling against the singly tagged $\bar D^0$ meson, $104.0\pm 10.9$ events for $D^0 \to K^-e ^+\nu_e$ and $9.0 \pm 3.6$ events for $D^0 \to \pi^-e^+\nu_e$ decays are observed. Those yield the absolute branching fractions to be $BF(D^0 \to K^-e^+\nu_e)=(3.82 \pm 0.40\pm 0.27)$ and $BF(D^0 \to \pi^-e^+\nu_e)=(0.33 \pm 0.13\pm 0.03)$. The vector form factors are determined to be $|f^K_+(0)| = 0.78 \pm 0.04 \pm 0.03$ and $|f^{\pi}_+(0)| = 0.73 \pm 0.14 \pm 0.06$. The ratio of the two form factors is measured to be $|f^{\pi}_+(0)/f^K_+(0)|= 0.93 \pm 0.19 \pm 0.07$.Comment: 6 pages, 5 figure

The σ\sigma pole in J/ψ→ωπ+π−J/\psi \to \omega \pi^+ \pi^-

Using a sample of 58 million $J/\psi$ events recorded in the BESII detector, the decay $J/\psi \to \omega \pi^+ \pi^-$ is studied. There are conspicuous $\omega f_2(1270)$ and $b_1(1235)\pi$ signals. At low $\pi \pi$ mass, a large broad peak due to the $\sigma$ is observed, and its pole position is determined to be $(541 \pm 39)$ - $i$ $(252 \pm 42)$ MeV from the mean of six analyses. The errors are dominated by the systematic errors.Comment: 15 pages, 6 figures, submitted to PL

Measurements of the Mass and Full-Width of the ηc\eta_c Meson

In a sample of 58 million $J/\psi$ events collected with the BES II detector, the process J/$\psi\to\gamma\eta_c$ is observed in five different decay channels: $\gamma K^+K^-\pi^+\pi^-$, $\gamma\pi^+\pi^-\pi^+\pi^-$, $\gamma K^\pm K^0_S \pi^\mp$ (with $K^0_S\to\pi^+\pi^-$), $\gamma \phi\phi$ (with $\phi\to K^+K^-$) and $\gamma p\bar{p}$. From a combined fit of all five channels, we determine the mass and full-width of $\eta_c$ to be $m_{\eta_c}=2977.5\pm1.0 ({stat.})\pm1.2 ({syst.})$ MeV/$c^2$ and $\Gamma_{\eta_c} = 17.0\pm3.7 ({stat.})\pm7.4 ({syst.})$ MeV/$c^2$.Comment: 9 pages, 2 figures and 4 table. Submitted to Phys. Lett.

Search for the Lepton Flavor Violation Processes J/ψ→J/\psi \to μτ\mu\tau and eτe\tau

The lepton flavor violation processes $J/\psi \to \mu\tau$ and $e\tau$ are searched for using a sample of 5.8$\times 10^7$ $J/\psi$ events collected with the BESII detector. Zero and one candidate events, consistent with the estimated background, are observed in $J/\psi \to \mu\tau, \tau\to e\bar\nu_e\nu_{\tau}$ and $J/\psi\to e\tau, \tau\to\mu\bar\nu_{\mu}\nu_{\tau}$ decays, respectively. Upper limits on the branching ratios are determined to be $Br(J/\psi\to\mu\tau)<2.0 \times 10^{-6}$ and $Br(J/\psi \to e\tau) < 8.3 \times10^{-6}$ at the 90% confidence level (C.L.).Comment: 9 pages, 2 figure

Observation of the decay \psip\rar\kstark

Using 14 million $\psi(2S)$ events collected with the BESII detector, branching fractions of \psip\rar\kstarkpm and \kstarknn are determined to be: \calB(\psip\rar\kstarkpm)=(2.9^{+1.3}_{-1.7}\pm0.4)\times 10^{-5} and \calB(\psip\rar\kstarknn)=(13.3^{+2.4}_{-2.7}\pm1.9)\times 10^{-5}. The results confirm the violation of the "12%" rule for these two decay channels with higher precision. A large isospin violation between the charged and neutral modes is observed.Comment: 5 pages, 3 figure

A Measurement of Psi(2S) Resonance Parameters

Cross sections for e+e- to hadons, pi+pi- J/Psi, and mu+mu- have been measured in the vicinity of the Psi(2S) resonance using the BESII detector operated at the BEPC. The Psi(2S) total width; partial widths to hadrons, pi+pi- J/Psi, muons; and corresponding branching fractions have been determined to be Gamma(total)= (264+-27) keV; Gamma(hadron)= (258+-26) keV, Gamma(mu)= (2.44+-0.21) keV, and Gamma(pi+pi- J/Psi)= (85+-8.7) keV; and Br(hadron)= (97.79+-0.15)%, Br(pi+pi- J/Psi)= (32+-1.4)%, Br(mu)= (0.93+-0.08)%, respectively.Comment: 8 pages, 6 figure

Measurement of Branching Ratios for ηc\eta_c Hadronic Decays

In a sample of 58 million $J/\psi$ events collected with the BES II detector, the process J/$\psi\to\gamma\eta_c$ is observed in five decay channels: $\eta_c \to K^+K^-\pi^+\pi^-$, $\pi^+\pi^-\pi^+\pi^-$, $K^\pm K^0_S \pi^\mp$ (with $K^0_S\to\pi^+\pi^-$), $\phi\phi$ (with $\phi\to K^+K^-$) and $p\bar{p}$. From these signals, we determine $Br(J/\psi\to\gamma\eta_c)\times Br(\eta_c\to K^+K^-\pi^+\pi^-)$ $=(1.5\pm0.2\pm0.2)\times10^{-4}$, $Br(J/\psi\to\gamma\eta_c)\times Br(\eta_c\to \pi^+\pi^-\pi^+\pi^-)$ $=(1.3\pm0.2\pm0.4)\times10^{-4}$, $Br(J/\psi\to\gamma\eta_c)\times Br(\eta_c\to K^\pm K_{S}^{0}\pi^\mp)$ $=(2.2\pm0.3\pm0.5)\times10^{-4}$, $Br(J/\psi\to\gamma\eta_c)\times Br(\eta_c\to \phi\phi)$ $=(3.3\pm0.6\pm0.6)\times10^{-5}$ and $Br(J/\psi\to\gamma\eta_c)\times Br(\eta_c\to p\bar{p})$ $=(1.9\pm0.3\pm0.3)\times10^{-5}$.Comment: 8 pages, 1 figures and 4 table. Submitted to Phys. Lett.

Evidence of psi(3770) non-DD-bar Decay to J/psi pi+pi-

Evidence of $\psi(3770)$ decays to a non-${D \bar D}$ final state is observed. A total of $11.8 \pm 4.8 \pm 1.3$ \psi(3770) \to \PPJP events are obtained from a data sample of 27.7 $\rm {pb^{-1}}$ taken at center-of-mass energies around 3.773 GeV using the BES-II detector at the BEPC. The branching fraction is determined to be BF(\psi(3770) \to \PPJP)=(0.34\pm 0.14 \pm 0.09)%, corresponding to the partial width of \Gamma(\psi(3770) \to \PPJP) = (80 \pm 33 \pm 23) keV.Comment: 8 pages, 7 figures, Submitted to Physics Letters

Measurements of J/psi --> p \bar{p}

The process J/\psi --> p \bar{p} is studied using 57.7 X 10^6 J/\psi events collected with the BESII detector at the Beijing Electron Positron Collider. The branching ratio is determined to be Br(J/\psi --> p \bar{p})=(2.26 +- 0.01 +- 0.14) X 10^{-3}, and the angular distribution is well described by \frac{dN}{d cos\theta_p}=1+\alpha\cos^2\theta_p with \alpha = 0.676 +- 0.036 +- 0.042, where \theta_p is the angle between the proton and beam directions. The value of \alpha obtained is in good agreement with the predictions of first-order QCD.Comment: 6 pages, 2 figures, RevTex4, Submitted to Phys.Lett.