Using 7.33  fb^{-1} of e^{+}e^{-} collision data collected by the BESIII detector at center-of-mass energies in the range of sqrt[s]=4.128-4.226  GeV, we search for the rare decays D_{s}^{+}→h^{+}(h^{0})e^{+}e^{-}, where h represents a kaon or pion. By requiring the e^{+}e^{-} invariant mass to be consistent with a ϕ(1020), 0.98<M(e^{+}e^{-})<1.04  GeV/c^{2}, the decay D_{s}^{+}→π^{+}ϕ, ϕ→e^{+}e^{-} is observed with a statistical significance of 7.8σ, and evidence for the decay D_{s}^{+}→ρ^{+}ϕ, ϕ→e^{+}e^{-} is found for the first time with a statistical significance of 4.4σ. The decay branching fractions are measured to be B(D_{s}^{+}→π^{+}ϕ,ϕ→e^{+}e^{-})=(1.17_{-0.21}^{+0.23}±0.03)×10^{-5}, and B(D_{s}^{+}→ρ^{+}ϕ,ϕ→e^{+}e^{-})=(2.44_{-0.62}^{+0.67}±0.16)×10^{-5}, where the first uncertainties are statistical and the second systematic. No significant signals for the three four-body decays of D_{s}^{+}→π^{+}π^{0}e^{+}e^{-}, D_{s}^{+}→K^{+}π^{0}e^{+}e^{-}, and D_{s}^{+}→K_{S}^{0}π^{+}e^{+}e^{-} are observed. For D_{s}^{+}→π^{+}π^{0}e^{+}e^{-}, the ϕ mass region is vetoed to minimize the long-distance effects. The 90% confidence level upper limits set on the branching fractions of these decays are in the range of (7.0-8.1)×10^{-5}.

Using 2.92~fb$^{-1}$ of electron-positron annihilation data collected at $\sqrt{s} = 3.773$~GeV with the BESIII detector, we obtain the first measurements of the absolute branching fraction $\mathcal{B}(D^+ \to K^0_L e^+ \nu_e) = (4.481 \pm 0.027(\mathrm{stat.}) \pm 0.103(\mathrm{sys.}))\%$ and the $CP$ asymmetry $A_{CP}^{D^+ \to K^0_L e^+ \nu_e} = (-0.59 \pm 0.60(\mathrm{stat.}) \pm 1.48(\mathrm{sys.}))\%$. From the $D^+ \to K^0_L e^+ \nu_e$ differential decay rate distribution, the product of the hadronic form factor and the magnitude of the CKM matrix element, $f_{+}^{K}(0)|V_{cs}|$, is determined to be $0.728 \pm 0.006(\mathrm{stat.}) \pm 0.011(\mathrm{sys.})$. Using $|V_{cs}|$ from the SM constrained fit with the measured $f_{+}^{K}(0)|V_{cs}|$, $f_{+}^{K}(0) = 0.748 \pm 0.007(\mathrm{stat.}) \pm 0.012(\mathrm{sys.})$ is obtained, and utilizing the unquenched LQCD calculation for $f_{+}^{K}(0)$, $|V_{cs}| = 0.975 \pm 0.008(\mathrm{stat.}) \pm 0.015(\mathrm{sys.}) \pm 0.025(\mathrm{LQCD})$.

The objective of this study was to determine the role and mechanism of S-phase kinase-associated protein 2 (Skp2) in colorectal cancer cell proliferation and survival both in vitro and in vivo. Adenoviral vector expressing Skp2 short hairpin RNA was transduced into SW480 cells. The effects of Skp2 on cell cycle and survival were assessed by Flow Cytometry. Cell proliferation was analyzed by MTT assay. The expression of cell cycle regulators p16 and p27 were measured by western blot. In vivo, human colorectal cancer was produced by xenograft of cancer cells in nude mouse. Tumor growth inhibitory rate was calculated to generate growth curve. Tumor growth was monitored by examining proliferating cell nuclear antigen expression, whereas tumor cell apoptosis was detected by TdT-mediated dUTP nick-end labeling (TUNEL) staining. Knockdown of Skp2 blocked SW480 tumor cell growth and induced cell apoptosis. Skp2 appeared to be very important for the progression of cell cycle at G1/S phase. In vivo, blockade of Skp2 expression inhibited tumor growth and induced tumor apoptosis. Mechanistically, Skp2 regulated the expression of both p27 and p16 both in vitro and in vivo. The conclusion that we derive from this study is that Skp2 regulates colorectal cancer cell growth by inhibiting the expression of cell cycle regulator p27 and p16.

Radiative decays of the radially excited charmonium resonance, \psi(2S), into \pi\pi, K Kbar and \eta\eta final states have been measured in a sample of 3.96 * 10^6 \psi(2S) events collected by the BES collaboration. The branching ratios B(\psi(2S) ->\gamma f_{2}(1270)) = (2.27 +- 0.26 +- 0.39) * 10^{-4} and B(\psi(2S) ->\gamma f_0(1710)) * B(f_0(1710) ->K^+ K^-) = (5.59 +- 1.12 +- 0.93) * 10^{-5} are obtained. When compared to the corresponding radiative J/\psi decays, the observed \psi(2S) radiative decay rates into \gamma f_2(1270) and \gamma f_0(1710) are consistent with the 15% rule.

With 7.8 million produced J/psi events collected by the BES detector at the BEPC, the decay J/psi-->Sigma(0)Sigma(0) is analysed. The branching ratio is measured to be BR(J/psi-->Sigma(0)Sigma(0)) = (0.97 +/- 0.04 +/- 0.24) x 10(-3). The angular distribution is of the form dN/dcostheta = N-0(1 + alphacos(2)theta) with alpha value of -0.21 +/- 0.27 +/- 0.13.

The branching fraction of the psi(2S) decay into tau(+) tau(-) has been measured for the first time using the BES detector at the Beijing Electron-Positron Collider. The result is B-tautau =(2.71+/-0.43+/-0.55) x 10(-3), where the first error is statistical and the second is systematic. This value, along with those for the branching fractions into e(+)c(-) and mu(+)mu(-) of this resonance, satisfy well the relation predicted by the sequential lepton hypothesis. Combining all these values with the leptonic width of the resonance, the total width of the psi(2S) is determined to be (252+/-37) keV.

We report a measurement of the absolutely inclusive semileptonic branching fractions of D- and (D-0) over bar mesons, using a data sample of 22.3 pb(-1) collected with BES detector at BEPC e(+) e Collider at roots = 4.03 GeV and based on the method of combinative D+ and D-0 single and double tags. The measured values of the branching fractions for D- --> e(-) X and (D-0) over bar --> e(-) X are ( 21.8 +/- 8.5 +/- 4.2)% and (8.9 +/- 3.0 +/- 1.6)%, respectively. The measured ratio of the branching fractions is BF(D- --> e(-) X)/BF (D0 --> e (-) X) -2.4 +/- 1.7 +/- 0.8.

We report values of R = sigma(e(+)e(-)-->hadrons)/sigma(e(+)e(-)-->mu(+)mu(-)) for 85 center-of-mass energies between 2 and 5 GeV measured with the upgraded Beijing Spectrometer at the Beijing Electron-Positron Collider.

We report the results of a search for the semileptonic decays D+ --> phie(+) nu, D+ --> phiK(-) pi(+) e(+) nu, D-0 --> phiK(-) e(+) nu and D-0 --> phiK(-) mu(+) nu using the BES detector at the BEPC e(+) e(-) Collider. Using a data sample of 22.3pb(-1) collected at the center-of-mass energy roots = 4.03GeV, we select 2472 +/- 87D(tag)(-) DX and 7628 +/- 149 (D) over bar (0)(tag) DX singly tagged D events, where the X could be gamma, pi(0) and/or pi(+/-). Based on the method of "combined D+ and D-0 single and double tags", we determine that 2471 +/- 218 D+ X and 7629 +/- 251 D-0 X are contained in the recoil side of the singly tagged neutral and charged D mesons, respectively. No events for the 4 semileptonic decay modes are observed in the recoil side of the tagged D mesons. The 90 % confidence-level upper limits of B(D+-W V) < 1.38 %, B(D+ --> phiK(-) pi(+) e(-) nu) < 2.01 %, B(D-0 --> phiK(-) e(+) nu) < 0.53 % and B (D-0 --> phiK(-) mu(+) nu) < 0.53 % are determined from the search for the semileptonic decays of D+ and D-0.

We present the results of a search for leptoquark (LQ) pairs in (85.2 +/- 3.7) pb(-1) of p (p) over bar collider data collected by the D0 experiment at the Fermilab Tevatron. We observe no evidence for leptoquark production and set a limit on sigma(p (p) over bar -->LQ (LQ) over bar --> nunu + jets) as a function of the mass of the leptoquark (m(LQ)) . Assuming the decay LQ --> nuq, we exclude scalar leptoquarks for m(LQ) < 98 GeV/c(2), and vector leptoquarks for m(LQ) < 200 GeV/c(2) and coupling which produces the minimum cross section, at a 95% confidence level.

Data are presented on the reaction J/psi -->> using 7.8 x 10(6) J/psi triggers collected by the BEjing Spectrometer (BES). A partial wave analysis is performed. A clear enhancement near the p eta((p) over bar eta) threshold is observed. It is fitted with a J(P) = 1/2(-) resonance with mass M = 1530 +/- 10 MeV and width Gamma = 95 +/- 25 MeV. In addition, there is a peak around 1650 MeV with J(P) = 1/2(-) preferred also, fitted with M = 1637 +/- 20 MeV and Gamma = 145(-45)(+80) MeV. These two N* resonances are believed to be the two well established states, S-11(1535) and S-11(1650). respectively. It is the first partial wave study of the production of these resonances from J/psi decays. (C) 2001 Published by Elsevier Science B.V.

The Beijing Spectrometer (BES) detector is a general purpose solenoid detector at the Beijing Electron Positron Collider (BEPC) in Beijing, China, that has collected large numbers of J/ψ, ψ′, Ds, D and τ events. In this paper, we describe the recent upgrade of the initial BES detector (BESI) to the improved BESII detector.

A sample of 3.95M psi (2S) decays registered in the BES detector are used to study final states containing pairs of octet and decuplet baryons. We report branching fractions for psi (2S)--> p(p) over bar, (Lambda )over bar>, Sigma (0) )over bar>(0), Xi (-) )over bar>(+) Delta (++) )over bar>(--), Sigma (+)(1385) )over bar>(-)(1385). Xi (0)(1530) )over bar>(0)(1530). and Omega (-) )over bar>(+). These results are compared to expectations based on the SU(3)-flavor symmetry, factorization. and perturbative QCD.

Data are presented on the reaction J/ψ→pp̄η using 7.8×106J/ψ triggers collected by the BEjing Spectrometer (BES). A partial wave analysis is performed. A clear enhancement near the pη(p̄η) threshold is observed. It is fitted with a JP=12− resonance with mass M=1530±10 MeV and width Γ=95±25 MeV. In addition, there is a peak around 1650 MeV with JP=12− preferred also, fitted with M=1647±20 MeV and Γ=145+80−45 MeV. These two N∗ resonances are believed to be the two well established states, S11(1535) and S11(1650), respectively. It is the first partial wave study of the production of these resonances from J/ψ decays.

The first measurement of B(D-0 --> phi X-0) and an upper limit for B(D+ --> phi X+) are determined from 22.3 pb(-1) of e(+)e(-) annihilation data at a c.m. energy of 4.03 GeV. The data were recorded by the Beijing Spectrometer (BES) at BEPC. A recoil charge method is applied to charm threshold data to determine the charge of the D meson in the recoil from 9054+/-309+/-416 reconstructed D-0, D+ mesons. The branching fractions B(D0 --> phi X-0) = (1.71(-0.71)(+0.76) +/- 0.17)%, and B(D+ --> phi X+) < 1.8% are determined from 10 events with a reconstructed D and a recoiling phi. In addition, a 90% C.L. upper limit of B(D+ --> phi e(+)X(0)) < 1.6% is determined from a search for semileptonic decays of the D+.