157 research outputs found

    Pairing Correlations in a Generalized Hubbard Model for the Cuprates

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    Using numerical diagonalization of a 4x4 cluster, we calculate on-site s, extended s and d pairing correlation functions (PCF) in an effective generalized Hubbard model for the cuprates, with nearest-neighbor correlated hopping and next nearest-neighbor hopping t'. The vertex contributions (VC) to the PCF are significantly enhanced, relative to the t-t'-U model. The behavior of the PCF and their VC, and signatures of anomalous flux quantization, indicate superconductivity in the d-wave channel for moderate doping and in the s-wave channel for high doping and small U.Comment: 5 pages, 5 figure

    The Energy of Regular Black Hole in General Relativity Coupled to Nonlinear Electrodynamics

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    According to the Einstein, Weinberg, and M{\o}ller energy-momentum complexes, we evaluate the energy distribution of the singularity-free solution of the Einstein field equations coupled to a suitable nonlinear electrodynamics suggested by Ay\'{o}n-Beato and Garc\'{i}a. The results show that the energy associated with the definitions of Einstein and Weinberg are the same, but M{\o}ller not. Using the power series expansion, we find out that the first two terms in the expression are the same as the energy distributions of the Reissner-Nordstr\"{o}m solution, and the third term could be used to survey the factualness between numerous solutions of the Einstein field eqautions coupled to a nonlinear electrodynamics.Comment: 11 page

    A Measurement of Psi(2S) Resonance Parameters

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    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

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

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    In a sample of 58 million J/ψJ/\psi events collected with the BES II detector, the process J/ψγηc\psi\to\gamma\eta_c is observed in five different decay channels: γK+Kπ+π\gamma K^+K^-\pi^+\pi^-, γπ+ππ+π\gamma\pi^+\pi^-\pi^+\pi^-, γK±KS0π\gamma K^\pm K^0_S \pi^\mp (with KS0π+πK^0_S\to\pi^+\pi^-), γϕϕ\gamma \phi\phi (with ϕK+K\phi\to K^+K^-) and γppˉ\gamma p\bar{p}. From a combined fit of all five channels, we determine the mass and full-width of ηc\eta_c to be mηc=2977.5±1.0(stat.)±1.2(syst.)m_{\eta_c}=2977.5\pm1.0 ({stat.})\pm1.2 ({syst.}) MeV/c2c^2 and Γηc=17.0±3.7(stat.)±7.4(syst.)\Gamma_{\eta_c} = 17.0\pm3.7 ({stat.})\pm7.4 ({syst.}) MeV/c2c^2.Comment: 9 pages, 2 figures and 4 table. Submitted to Phys. Lett.

    Treatment Outcomes of Patients With Multidrug-Resistant and Extensively Drug-Resistant Tuberculosis According to Drug Susceptibility Testing to First- and Second-line Drugs: An Individual Patient Data Meta-analysis

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    The clinical validity of drug susceptibility testing (DST) for pyrazinamide, ethambutol, and second-line antituberculosis drugs is uncertain. In an individual patient data meta-analysis of 8955 patients with confirmed multidrug-resistant tuberculosis, DST results for these drugs were associated with treatment outcome

    Measurement of Branching Ratios for ηc\eta_c Hadronic Decays

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    In a sample of 58 million J/ψJ/\psi events collected with the BES II detector, the process J/ψγηc\psi\to\gamma\eta_c is observed in five decay channels: ηcK+Kπ+π\eta_c \to K^+K^-\pi^+\pi^-, π+ππ+π\pi^+\pi^-\pi^+\pi^-, K±KS0πK^\pm K^0_S \pi^\mp (with KS0π+πK^0_S\to\pi^+\pi^-), ϕϕ\phi\phi (with ϕK+K\phi\to K^+K^-) and ppˉp\bar{p}. From these signals, we determine Br(J/ψγηc)×Br(ηcK+Kπ+π)Br(J/\psi\to\gamma\eta_c)\times Br(\eta_c\to K^+K^-\pi^+\pi^-) =(1.5±0.2±0.2)×104=(1.5\pm0.2\pm0.2)\times10^{-4}, Br(J/ψγηc)×Br(ηcπ+ππ+π)Br(J/\psi\to\gamma\eta_c)\times Br(\eta_c\to \pi^+\pi^-\pi^+\pi^-) =(1.3±0.2±0.4)×104=(1.3\pm0.2\pm0.4)\times10^{-4}, Br(J/ψγηc)×Br(ηcK±KS0π)Br(J/\psi\to\gamma\eta_c)\times Br(\eta_c\to K^\pm K_{S}^{0}\pi^\mp) =(2.2±0.3±0.5)×104=(2.2\pm0.3\pm0.5)\times10^{-4}, Br(J/ψγηc)×Br(ηcϕϕ)Br(J/\psi\to\gamma\eta_c)\times Br(\eta_c\to \phi\phi) =(3.3±0.6±0.6)×105=(3.3\pm0.6\pm0.6)\times10^{-5} and Br(J/ψγηc)×Br(ηcppˉ)Br(J/\psi\to\gamma\eta_c)\times Br(\eta_c\to p\bar{p}) =(1.9±0.3±0.3)×105=(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-

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    Evidence of ψ(3770)\psi(3770) decays to a non-DDˉ{D \bar D} final state is observed. A total of 11.8±4.8±1.311.8 \pm 4.8 \pm 1.3 \psi(3770) \to \PPJP events are obtained from a data sample of 27.7 pb1\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}

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    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.

    Strategies for Controlled Placement of Nanoscale Building Blocks

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    The capability of placing individual nanoscale building blocks on exact substrate locations in a controlled manner is one of the key requirements to realize future electronic, optical, and magnetic devices and sensors that are composed of such blocks. This article reviews some important advances in the strategies for controlled placement of nanoscale building blocks. In particular, we will overview template assisted placement that utilizes physical, molecular, or electrostatic templates, DNA-programmed assembly, placement using dielectrophoresis, approaches for non-close-packed assembly of spherical particles, and recent development of focused placement schemes including electrostatic funneling, focused placement via molecular gradient patterns, electrodynamic focusing of charged aerosols, and others
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