4,609 research outputs found

    Charged-rotating black holes and black strings in higher dimensional Einstein-Maxwell theory with a positive cosmological constant

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    We present arguments for the existence of charged, rotating black holes in d=2N+1d=2N+1 dimensions, with d≄5d\geq 5 with a positive cosmological constant. These solutions posses both, a regular horizon and a cosmological horizon of spherical topology and have NN equal-magnitude angular momenta. They approach asymptotically the de Sitter spacetime background. The counterpart equations for d=2N+2d=2N+2 are investigated, by assuming that the fields are independant of the extra dimension yy, leading to black strings solutions. These solutions are regular at the event horizon. The asymptotic form of the metric is not the de Sitter form and exhibit a naked singularity at finite proper distance.Comment: 21 pages, 9 figure

    Search for D to phi l nu and measurement of the branching fraction for D to phi pi

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    Using a data sample of integrated luminosity of about 33 pb−1^{-1} collected around 3.773 GeV with the BESII detector at the BEPC collider, the semileptonic decays D+→ϕe+ÎœeD^+ \to \phi e ^+\nu_e, D+→ϕΌ+ΜΌD^+ \to \phi \mu^+\nu_\mu and the hadronic decay D+→ϕπ+D^+ \to \phi \pi^+ are studied. The upper limits of the branching fractions are set to be BF(D+→ϕe+Îœe)<BF(D^+ \to \phi e ^+\nu_e) < 2.01% and BF(D+→ϕΌ+ΜΌ)<BF(D^+ \to \phi \mu^+ \nu_\mu) < 2.04% at the 90% confidence level. The ratio of the branching fractions for D+→ϕπ+D^+ \to \phi \pi^+ relative to D+→K−π+π+D^+ \to K^-\pi^+\pi^+ is measured to be 0.057±0.011±0.0030.057 \pm 0.011 \pm 0.003. In addition, the branching fraction for D+→ϕπ+D^+ \to \phi \pi^+ is obtained to be (5.2±1.0±0.4)×10−3(5.2 \pm 1.0 \pm 0.4) \times 10^{-3}.Comment: 6 pages, 5 figures, to be published in Eur.Phys.J.

    Measurements of branching fractions for inclusive K0~/K0 and K*(892)+- decays of neutral and charged D mesons

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    Using the data sample of about 33 pb-1 collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we have studied inclusive K0~/K0 and K*(892)+- decays of D0 and D+ mesons. The branching fractions for the inclusive K0~/K0 and K*(892)- decays are measured to be BF(D0 to K0~/K0 X)=(47.6+-4.8+-3.0)%, BF(D+ to K0~/K0 X)=(60.5+-5.5+-3.3)%, BF(D0 to K*- X)=(15.3+- 8.3+- 1.9)% and BF(D+ to K*- X)=(5.7+- 5.2+- 0.7)%. The upper limits of the branching fractions for the inclusive K*(892)+ decays are set to be BF(D0 to K*+ X)<3.6% and BF(D+ to K*+ X) <20.3% at 90% confidence level

    Direct Measurements of the Branching Fractions for Inclusive K±K^\pm and Inclusive Semileptonic Decays of D+D^+ and D0D^0 Mesons

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    With singly-tagged Dˉ\bar D samples selected from the data collected at and around 3.773 GeV with the BESII detector at the BEPC collider, we have measured the branching fractions for the inclusive K±K^\pm decays of D+D^+ and D0D^0 mesons, which are BF(D+→K−X)=(24.7±1.3±1.2)BF(D^+\to K^-X) = (24.7 \pm 1.3 \pm 1.2)%, BF(D+→K+X)=(6.1±0.9±0.4)BF(D^+\to K^+X) = (6.1 \pm 0.9 \pm 0.4) %, BF(D0→K−X)=(57.8±1.6±3.2)BF(D^0\to K^-X) = (57.8 \pm 1.6 \pm 3.2) % and BF(D0→K+X)=(3.5±0.7±0.3)BF(D^0\to K^+X) = (3.5 \pm 0.7 \pm 0.3) %, respectively. We have also measured the branching fractions for the inclusive semileptonic decays of D+D^+ and D0D^0 mesons to be BF(D+→e+X)=(15.2±0.9±0.8)BF(D^+ \to e^+ X)=(15.2 \pm 0.9 \pm 0.8)% and BF(D0→e+X)=(6.3±0.7±0.4)BF(D^0 \to e^+ X) =(6.3 \pm 0.7 \pm 0.4) %. These yield the ratio of their partial widths to be Γ(D+→e+X)/Γ(D0→e+X)=0.95±0.12±0.07\Gamma(D^+ \to e^+X)/\Gamma(D^0 \to e^+X)=0.95 \pm 0.12 \pm 0.07.Comment: 6 pages, 5 figure

    Plasmofluidic Disk Resonators

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    Waveguide-coupled silicon ring or disk resonators have been used for optical signal processing and sensing. Large-scale integration of optical devices demands continuous reduction in their footprints, and ultimately they need to be replaced by silicon-based plasmonic resonators. However, few waveguide-coupled silicon-based plasmonic resonators have been realized until now. Moreover, fluid cannot interact effectively with them since their resonance modes are strongly confined in solid regions. To solve this problem, this paper reports realized plasmofluidic disk resonators (PDRs). The PDR consists of a submicrometer radius silicon disk and metal laterally surrounding the disk with a 30-nm-wide channel in between. The channel is filled with fluid, and the resonance mode of the PDR is strongly confined in the fluid. The PDR coupled to a metal-insulator-silicon-insulator-metal waveguide is implemented by using standard complementary metal oxide semiconductor technology. If the refractive index of the fluid increases by 0.141, the transmission spectrum of the waveguide coupled to the PDR of radius 0.9 mu m red-shifts by 30 nm. The PDR can be used as a refractive index sensor requiring a very small amount of analyte. Plus, the PDR filled with liquid crystal may be an ultracompact intensity modulator which is effectively controlled by small driving voltageopen

    Predictive ability of logistic regression, auto-logistic regression and neural network models in empirical land-use change modeling: a case study

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    The objective of this study is to compare the abilities of logistic, auto-logistic and artificial neural network (ANN) models for quantifying the relationships between land uses and their drivers. In addition, the application of the results obtained by the three techniques is tested in a dynamic land-use change model (CLUE-s) for the Paochiao watershed region in Taiwan. Relative operating characteristic curves (ROCs), kappa statistics, multiple resolution validation and landscape metrics were used to assess the ability of the three techniques in estimating the relationship between driving factors and land use and its subsequent application in land-use change models. The validation results illustrate that for this case study ANNs constitute a powerful alternative for the use of logistic regression in empirical modeling of spatial land-use change processes. ANNs provide in this case a better fit between driving factors and land-use pattern. In addition, auto-logistic regression performs better than logistic regression and nearly as well as ANNs. Auto-logistic regression and ANNs are considered especially useful when the performance of more conventional models is not satisfactory or the underlying data relationships are unknown. The results indicate that an evaluation of alternative techniques to specify relationships between driving factors and land use can improve the performance of land-use change models

    Measurement of the branching fractions of psi(2S) -> 3(pi+pi-) and J/psi -> 2(pi+pi-)

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    Using data samples collected at sqrt(s) = 3.686GeV and 3.650GeV by the BESII detector at the BEPC, the branching fraction of psi(2S) -> 3(pi+pi-) is measured to be [4.83 +- 0.38(stat) +- 0.69(syst)] x 10^-4, and the relative branching fraction of J/psi -> 2(pi+pi-) to that of J/psi -> mu+mu- is measured to be [5.86 +- 0.19(stat) +- 0.39(syst)]% via psi(2S) -> (pi+pi-)J/psi, J/psi -> 2(pi+pi-). The electromagnetic form factor of 3(pi+pi-) is determined to be 0.21 +- 0.02 and 0.20 +- 0.01 at sqrt(s) = 3.686GeV and 3.650GeV, respectively.Comment: 17pages, 7 figures, submitted to Phys. Rev.

    Measurement of the chi_{c2} Polarization in psi(2S) to gamma chi_{c2}

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    The polarization of the chi_{c2} produced in psi(2S) decays into gamma chi_{c2} is measured using a sample of 14*10^6 psi(2S) events collected by BESII at the BEPC. A fit to the chi_{c2} production and decay angular distributions in psi(2S) to gamma chi_{c2}, chi_{c2} to pi pi and KK yields values x=A_1/A_0=2.08+/-0.44 and y=A_2/A_0=3.03 +/-0.66, with a correlation rho=0.92 between them, where A_{0,1,2} are the chi_{c2} helicity amplitudes. The measurement agrees with a pure E1 transition, and M2 and E3 contributions do not differ significantly from zero.Comment: 6 pages, 4 figures, 1 tabl

    Measurements of J/psi decays into phi pi^0, phi eta, and phi eta^prime

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    Based on 5.8x10^7 J/psi events detected in BESII, the branching fractions of J/psi--> phi eta and phi eta^prime are measured for different eta and eta^prime decay modes. The results are significantly higher than previous measurements. An upper limit on B(J/psi--> phi pi^0) is also obtained.Comment: 9 pages, 10 figure
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