3,667 research outputs found

    Global statistics of liquid water content and effective number concentration of water clouds over ocean derived from combined CALIPSO and MODIS measurements

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    This study presents an empirical relation that links the volume extinction coefficients of water clouds, the layer integrated depolarization ratios measured by lidar, and the effective radii of water clouds derived from collocated passive sensor observations. Based on Monte Carlo simulations of CALIPSO lidar observations, this method combines the cloud effective radius reported by MODIS with the lidar depolarization ratios measured by CALIPSO to estimate both the liquid water content and the effective number concentration of water clouds. The method is applied to collocated CALIPSO and MODIS measurements obtained during July and October of 2006, and January 2007. Global statistics of the cloud liquid water content and effective number concentration are presented

    Precision measurement of the branching fractions of J/psi -> pi+pi-pi0 and psi' -> pi+pi-pi0

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    We study the decays of the J/psi and psi' mesons to pi+pi-pi0 using data samples at both resonances collected with the BES III detector in 2009. We measure the corresponding branching fractions with unprecedented precision and provide mass spectra and Dalitz plots. The branching fraction for J/psi -> pi+pi-pi0 is determined to be (2.137 +- 0.004 (stat.) +0.058-0.056 (syst.) +0.027-0.026 (norm.))*10-2, and the branching fraction for psi' -> pi+pi-pi0 is measured as (2.14 +- 0.03 (stat.) +0.08-0.07 (syst.) +0.09-0.08 (norm.))*10-4. The J/psi decay is found to be dominated by an intermediate rho(770) state, whereas the psi' decay is dominated by di-pion masses around 2.2 GeV/c2, leading to strikingly different Dalitz distributions.Comment: 15 pages, 2 figure

    First observation of the M1 transition ψ(3686)γηc(2S)\psi(3686)\to \gamma\eta_c(2S)

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    Using a sample of 106 million \psi(3686) events collected with the BESIII detector at the BEPCII storage ring, we have made the first measurement of the M1 transition between the radially excited charmonium S-wave spin-triplet and the radially excited S-wave spin-singlet states: \psi(3686)\to\gamma\eta_c(2S). Analyses of the processes \psi(2S)\to \gamma\eta_c(2S) with \eta_c(2S)\to \K_S^0 K\pi and K^+K^-\pi^0 gave an \eta_c(2S) signal with a statistical significance of greater than 10 standard deviations under a wide range of assumptions about the signal and background properties. The data are used to obtain measurements of the \eta_c(2S) mass (M(\eta_c(2S))=3637.6\pm 2.9_\mathrm{stat}\pm 1.6_\mathrm{sys} MeV/c^2), width (\Gamma(\eta_c(2S))=16.9\pm 6.4_\mathrm{stat}\pm 4.8_\mathrm{sys} MeV), and the product branching fraction (\BR(\psi(3686)\to \gamma\eta_c(2S))\times \BR(\eta_c(2S)\to K\bar K\pi) = (1.30\pm 0.20_\mathrm{stat}\pm 0.30_\mathrm{sys})\times 10^{-5}). Combining our result with a BaBar measurement of \BR(\eta_c(2S)\to K\bar K \pi), we find the branching fraction of the M1 transition to be \BR(\psi(3686)\to\gamma\eta_c(2S)) = (6.8\pm 1.1_\mathrm{stat}\pm 4.5_\mathrm{sys})\times 10^{-4}.Comment: 7 pages, 1 figure, 1 tabl

    Study of J/ψppˉJ/\psi\to p\bar{p} and J/ψnnˉJ/\psi\to n\bar{n}

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    The decays J/ψppˉJ/\psi\to p\bar{p} and J/ψnnˉJ/\psi\to n\bar{n} have been investigated with a sample of 225.2 million J/ψJ/\psi events collected with the BESIII detector at the BEPCII e+ee^+e^- collider. The branching fractions are determined to be B(J/ψppˉ)=(2.112±0.004±0.031)×103\mathcal{B}(J/\psi\to p\bar{p})=(2.112\pm0.004\pm0.031)\times10^{-3} and B(J/ψnnˉ)=(2.07±0.01±0.17)×103\mathcal{B}(J/\psi\to n\bar{n})=(2.07\pm0.01\pm0.17)\times10^{-3}. Distributions of the angle θ\theta between the proton or anti-neutron and the beam direction are well described by the form 1+αcos2θ1+\alpha\cos^2\theta, and we find α=0.595±0.012±0.015\alpha=0.595\pm0.012\pm0.015 for J/ψppˉJ/\psi\to p\bar{p} and α=0.50±0.04±0.21\alpha=0.50\pm0.04\pm0.21 for J/ψnnˉJ/\psi\to n\bar{n}. Our branching-fraction results suggest a large phase angle between the strong and electromagnetic amplitudes describing the J/ψNNˉJ/\psi\to N\bar{N} decay.Comment: 16 pages, 13 figures, the 2nd version, submitted to PR

    Observation of χc1\chi_{c1} decays into vector meson pairs ϕϕ\phi\phi, ωω\omega\omega, and ωϕ\omega\phi

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    Decays of χc1\chi_{c1} to vector meson pairs ϕϕ\phi\phi, ωω\omega\omega and ωϕ\omega\phi are observed for the first time using (106±4)×106(106\pm4)\times 10^6 \psip events accumulated at the BESIII detector at the BEPCII e+ee^+e^- collider. The branching fractions are measured to be (4.4±0.3±0.5)×104(4.4\pm 0.3\pm 0.5)\times 10^{-4}, (6.0±0.3±0.7)×104(6.0\pm 0.3\pm 0.7)\times 10^{-4}, and (2.2±0.6±0.2)×105(2.2\pm 0.6\pm 0.2)\times 10^{-5}, for χc1ϕϕ\chi_{c1}\to \phi\phi, ωω\omega\omega, and ωϕ\omega\phi, respectively. The observation of χc1\chi_{c1} decays into a pair of vector mesons ϕϕ\phi\phi, ωω\omega\omega and ωϕ\omega\phi indicates that the hadron helicity selection rule is significantly violated in χcJ\chi_{cJ} decays. In addition, the measurement of χcJωϕ\chi_{cJ}\to \omega\phi gives the rate of doubly OZI-suppressed decay. Branching fractions for χc0\chi_{c0} and χc2\chi_{c2} decays into other vector meson pairs are also measured with improved precision.Comment: 4 pages, 2 figure

    First Observation of the Decays chi_{cJ} -> pi^0 pi^0 pi^0 pi^0

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    We present a study of the P-wave spin -triplet charmonium chi_{cJ} decays (J=0,1,2) into pi^0 pi^0 pi^0 pi^0. The analysis is based on 106 million \psiprime decays recorded with the BESIII detector at the BEPCII electron positron collider. The decay into the pi^0 pi^0 pi^0 pi^0 hadronic final state is observed for the first time. We measure the branching fractions B(chi_{c0} -> pi^0 pi^0 pi^0 pi^0)=(3.34 +- 0.06 +- 0.44)*10^{-3}, B(chi_{c1} -> pi^0 pi^0 pi^0 pi^0)=(0.57 +- 0.03 +- 0.08)*10^{-3}, and B(chi_{c2} -> pi^0 pi^0 pi^0 pi^0)=(1.21 +- 0.05 +- 0.16)*10^{-3}, where the uncertainties are statistical and systematical, respectively.Comment: 7 pages, 3 figure

    Observation of a charged charmoniumlike structure in e+e(DDˉ)±πe^+e^- \to (D^{*} \bar{D}^{*})^{\pm} \pi^\mp at s=4.26\sqrt{s}=4.26GeV

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    We study the process e+e(DDˉ)±πe^+e^- \to (D^{*} \bar{D}^{*})^{\pm} \pi^\mp at a center-of-mass energy of 4.26GeV using a 827pb1^{-1} data sample obtained with the BESIII detector at the Beijing Electron Positron Collider. Based on a partial reconstruction technique, the Born cross section is measured to be (137±9±15)(137\pm9\pm15)pb. We observe a structure near the (DDˉ)±(D^{*} \bar{D}^{*})^{\pm} threshold in the π\pi^\mp recoil mass spectrum, which we denote as the Zc±(4025)Z^{\pm}_c(4025). The measured mass and width of the structure are (4026.3±2.6±3.7)(4026.3\pm2.6\pm3.7)MeV/c2^2 and (24.8±5.6±7.7)(24.8\pm5.6\pm7.7)MeV, respectively. Its production ratio σ(e+eZc±(4025)π(DDˉ)±π)σ(e+e(DDˉ)±π)\frac{\sigma(e^+e^-\to Z^{\pm}_c(4025)\pi^\mp \to (D^{*} \bar{D}^{*})^{\pm} \pi^\mp)}{\sigma(e^+e^-\to (D^{*} \bar{D}^{*})^{\pm} \pi^\mp)} is determined to be 0.65±0.09±0.060.65\pm0.09\pm0.06. The first uncertainties are statistical and the second are systematic.Comment: 7 pages, 4 figures, 1 table; version accepted to be published in PR

    Higher-order multipole amplitude measurement in ψ(2S)γχc2\psi(2S)\to\gamma\chi_{c2}

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    Using 106×106106\times10^6 ψ(2S)\psi(2S) events collected with the BESIII detector at the BEPCII storage ring, the higher-order multipole amplitudes in the radiative transition ψ(2S)γχc2γππ/γKK\psi(2S)\to\gamma\chi_{c2}\to\gamma\pi\pi/\gamma KK are measured. A fit to the χc2\chi_{c2} production and decay angular distributions yields M2=0.046±0.010±0.013M2=0.046\pm0.010\pm0.013 and E3=0.015±0.008±0.018E3=0.015\pm0.008\pm0.018, where the first errors are statistical and the second systematic. Here M2M2 denotes the normalized magnetic quadrupole amplitude and E3E3 the normalized electric octupole amplitude. This measurement shows evidence for the existence of the M2M2 signal with 4.4σ4.4\sigma statistical significance and is consistent with the charm quark having no anomalous magnetic moment.Comment: 14 pages, 4 figure

    Study of χcJ\chi_{cJ} radiative decays into a vector meson

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    The decays χcJγV\chi_{cJ}\to\gamma V (V=ϕ,ρ0,ωV=\phi, \rho^0, \omega) are studied with a sample of radiative \psip\to\gamma\chi_{cJ} events in a sample of (1.06\pm0.04)\times 10^{8} \psip events collected with the BESIII detector. The branching fractions are determined to be: B(χc1γϕ)=(25.8±5.2±2.3)×106{\cal B}(\chi_{c1}\to \gamma\phi)=(25.8\pm 5.2\pm 2.3)\times 10^{-6}, B(χc1γρ0)=(228±13±22)×106{\cal B}(\chi_{c1}\to \gamma\rho^0)=(228\pm 13\pm 22)\times 10^{-6}, and B(χc1γω)=(69.7±7.2±6.6)×106{\cal B}(\chi_{c1}\to \gamma\omega)=(69.7\pm 7.2\pm 6.6)\times 10^{-6}. The decay χc1γϕ\chi_{c1}\to \gamma\phi is observed for the first time. Upper limits at the 90% confidence level on the branching fractions for χc0\chi_{c0} and \chict decays into these final states are determined. In addition, the fractions of the transverse polarization component of the vector meson in χc1γV\chi_{c1}\to \gamma V decays are measured to be 0.290.120.09+0.13+0.100.29_{-0.12-0.09}^{+0.13+0.10} for χc1γϕ\chi_{c1}\to \gamma\phi, 0.158±0.0340.014+0.0150.158\pm 0.034^{+0.015}_{-0.014} for χc1γρ0\chi_{c1}\to \gamma\rho^0, and 0.2470.0870.026+0.090+0.0440.247_{-0.087-0.026}^{+0.090+0.044} for χc1γω\chi_{c1}\to \gamma\omega, respectively. The first errors are statistical and the second ones are systematic.Comment: 8 pages, 3 figure

    Search for the Lepton Flavor Violation Process J/ψeμJ/\psi \to e\mu at BESIII

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    We search for the lepton-flavor-violating decay of the J/ψJ/\psi into an electron and a muon using (225.3±2.8)×106(225.3\pm2.8)\times 10^{6} J/ψJ/\psi events collected with the BESIII detector at the BEPCII collider. Four candidate events are found in the signal region, consistent with background expectations. An upper limit on the branching fraction of B(J/ψeμ)<1.5×107\mathcal{B}(J/\psi \to e\mu)< 1.5 \times 10^{-7} (90% C.L.) is obtained
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