807 research outputs found

    Ecological Effects of Fear: How Spatiotemporal Heterogeneity in Predation Risk Influences Mule Deer Access to Forage in a Sky‐Island System

    Get PDF
    Forage availability and predation risk interact to affect habitat use of ungulates across many biomes. Within sky‐island habitats of the Mojave Desert, increased availability of diverse forage and cover may provide ungulates with unique opportunities to extend nutrient uptake and/or to mitigate predation risk. We addressed whether habitat use and foraging patterns of female mule deer (Odocoileus hemionus) responded to normalized difference vegetation index (NDVI), NDVI rate of change (green‐up), or the occurrence of cougars (Puma concolor). Female mule deer used available green‐up primarily in spring, although growing vegetation was available during other seasons. Mule deer and cougar shared similar habitat all year, and our models indicated cougars had a consistent, negative effect on mule deer access to growing vegetation, particularly in summer when cougar occurrence became concentrated at higher elevations. A seemingly late parturition date coincided with diminishing NDVI during the lactation period. Sky‐island populations, rarely studied, provide the opportunity to determine how mule deer respond to growing foliage along steep elevation and vegetation gradients when trapped with their predators and seasonally limited by aridity. Our findings indicate that fear of predation may restrict access to the forage resources found in sky islands

    Studies of the decays D^0 \rightarrow K_S^0K^-\pi^+ and D^0 \rightarrow K_S^0K^+\pi^-

    Full text link
    The first measurements of the coherence factor R_{K_S^0K\pi} and the average strong--phase difference \delta^{K_S^0K\pi} in D^0 \to K_S^0 K^\mp\pi^\pm decays are reported. These parameters can be used to improve the determination of the unitary triangle angle \gamma\ in B^- \rightarrow D~K\widetilde{D}K^- decays, where D~\widetilde{D} is either a D^0 or a D^0-bar meson decaying to the same final state, and also in studies of charm mixing. The measurements of the coherence factor and strong-phase difference are made using quantum-correlated, fully-reconstructed D^0D^0-bar pairs produced in e^+e^- collisions at the \psi(3770) resonance. The measured values are R_{K_S^0K\pi} = 0.70 \pm 0.08 and \delta^{K_S^0K\pi} = (0.1 \pm 15.7)^\circ for an unrestricted kinematic region and R_{K*K} = 0.94 \pm 0.12 and \delta^{K*K} = (-16.6 \pm 18.4)^\circ for a region where the combined K_S^0 \pi^\pm invariant mass is within 100 MeV/c^2 of the K^{*}(892)^\pm mass. These results indicate a significant level of coherence in the decay. In addition, isobar models are presented for the two decays, which show the dominance of the K^*(892)^\pm resonance. The branching ratio {B}(D^0 \rightarrow K_S^0K^+\pi^-)/{B}(D^0 \rightarrow K_S^0K^-\pi^+) is determined to be 0.592 \pm 0.044 (stat.) \pm 0.018 (syst.), which is more precise than previous measurements.Comment: 38 pages. Version 3 updated to include the erratum information. Errors corrected in Eqs (25), (26), 28). Fit results updated accordingly, and external inputs updated to latest best known values. Typo corrected in Eq(3)- no other consequence

    Observation of the Dalitz Decay Ds+Ds+e+eD_{s}^{*+} \to D_{s}^{+} e^{+} e^{-}

    Full text link
    Using 586 pb1\textrm{pb}^{-1} of e+ee^{+}e^{-} collision data acquired at s=4.170\sqrt{s}=4.170 GeV with the CLEO-c detector at the Cornell Electron Storage Ring, we report the first observation of Ds+Ds+e+eD_{s}^{*+} \to D_{s}^{+} e^{+} e^{-} with a significance of 5.3σ5.3 \sigma. The ratio of branching fractions \calB(D_{s}^{*+} \to D_{s}^{+} e^{+} e^{-}) / \calB(D_{s}^{*+} \to D_{s}^{+} \gamma) is measured to be [0.720.13+0.15(stat)±0.10(syst)][ 0.72^{+0.15}_{-0.13} (\textrm{stat}) \pm 0.10 (\textrm{syst})]%, which is consistent with theoretical expectations

    Updated Measurement of the Strong Phase in D0 --> K+pi- Decay Using Quantum Correlations in e+e- --> D0 D0bar at CLEO

    Full text link
    We analyze a sample of 3 million quantum-correlated D0 D0bar pairs from 818 pb^-1 of e+e- collision data collected with the CLEO-c detector at E_cm = 3.77 GeV, to give an updated measurement of \cos\delta and a first determination of \sin\delta, where \delta is the relative strong phase between doubly Cabibbo-suppressed D0 --> K+pi- and Cabibbo-favored D0bar --> K+pi- decay amplitudes. With no inputs from other experiments, we find \cos\delta = 0.81 +0.22+0.07 -0.18-0.05, \sin\delta = -0.01 +- 0.41 +- 0.04, and |\delta| = 10 +28+13 -53-0 degrees. By including external measurements of mixing parameters, we find alternative values of \cos\delta = 1.15 +0.19+0.00 -0.17-0.08, \sin\delta = 0.56 +0.32+0.21 -0.31-0.20, and \delta = (18 +11-17) degrees. Our results can be used to improve the world average uncertainty on the mixing parameter y by approximately 10%.Comment: Minor revisions, version accepted by PR

    Search for rare and forbidden decays of charm and charmed-strange mesons to final states h^+- e^-+ e^+

    Get PDF
    We have searched for flavor-changing neutral current decays and lepton-number-violating decays of D^+ and D^+_s mesons to final states of the form h^+- e^-+ e^+, where h is either \pi or K. We use the complete samples of CLEO-c open-charm data, corresponding to integrated luminosities of 818 pb^-1 at the center-of-mass energy E_CM = 3.774 GeV containing 2.4 x 10^6 D^+D^- pairs and 602 pb^-1 at E_CM = 4.170 GeV containing 0.6 x 10^6 D^*+-_s D^-+_s pairs. No signal is observed in any channel, and we obtain 90% confidence level upper limits on branching fractions B(D^+ --> \pi^+ e^+ e^-) < 5.9 x 10^-6, B(D^+ --> \pi^- e^+ e^+) K^+ e^+ e^-) < 3.0 x 10^-6, B(D^+ --> K^- e^+ e^+) \pi^+ e^+ e^-) < 2.2 x 10^-5, B(D^+_s --> \pi^- e^+ e^+) K^+ e^+ e^-) < 5.2 x 10^-5, and B(D^+_s --> K^- e^+ e^+) < 1.7 x 10^-5.Comment: 9 pages, available through http://www.lns.cornell.edu/public/CLNS

    Branching fractions for Y(3S) -> pi^0 h_b and psi(2S) -> pi^0 h_c

    Full text link
    Using e^+e^- collision data corresponding to 5.88M Y(3S) [25.9M psi(2S)] decays and acquired by the CLEO III [CLEO-c] detectors operating at CESR, we study the single-pion transitions from Y(3S) [psi(2S)] to the respective spin-singlet states h_{b[c]}. Utilizing only the momentum of suitably selected transition-pi^0 candidates, we obtain the upper limit B(Y(3S) -> pi^0 h_b) < 1.2\times 10^{-3} at 90% confidence level, and measure B(psi(2S) -> pi^0 h_c) = (9.0+-1.5+-1.3)\times 10^{-4}. Signal sensitivities are enhanced by excluding very asymmetric pi^0 -> gamma gamma candidates.Comment: 12 pages 4 figures, version published in Physical Review

    Measurement of B(Ds+ -->ell+ nu) and the Decay Constant fDs From 600/pb of e+e- Annihilation Data Near 4170 MeV

    Full text link
    We examine e+e- --> Ds^-D_s^{*+} and Ds^{*-}Ds^{+} interactions at 4170 MeV using the CLEO-c detector in order to measure the decay constant fDs with good precision. Previously our measurements were substantially higher than the most precise lattice based QCD calculation of (241 +/- 3) MeV. Here we use the D_s^+ --> ell^+ nu channel, where the ell^+ designates either a mu^+ or a tau^+, when the tau^+ --> pi^+ anti-nu. Analyzing both modes independently, we determine B(D_s^+ --> mu^+ nu)= 0.565 +/- 0.045 +/- 0.017)%, and B(D_s^+ --> mu^+ nu)= (6.42 +/- 0.81 +/- 0.18)%. We also analyze them simultaneously to find an effective value of B^{eff}(D_s^+ --> mu^+ nu)= (0.591 +/- 0.037 +/- 0.018)% and fDs=(263.3 +/- 8.2 +/- 3.9) MeV. Combining with the CLEO-c value determined independently using D_s^+ --> tau^+ nu, tau^+ --> e^+ nu anti-nu decays, we extract fDs=(259.5 +/- 6.6 +/- 3.1) MeV. Combining with our previous determination of B(D^+ --> mu^+ nu), we extract the ratio fDs/fD+=1.26 +/- 0.06 +/- 0.02. No evidence is found for a CP asymmetry between Gamma(D_s^+ --> mu^+\nu) and \Gamma(D_s^- --> mu^- nu); specifically the fractional difference in rates is measured to be (4.8 +/- 6.1)%. Finally, we find B(D_s^+ --> e^+ nu) < 1.2x10^{-4} at 90% confidence level.Comment: 26 pages, 16 figure

    Measurement of \cal{B}(D^+ --> mu^+ nu) and the Pseudoscalar Decay Constant fD+f_{D^+}

    Full text link
    In 60 pb-1 of data taken on the psi(3770) resonance with the CLEO-c detector, we find 8 D+ to mu+ nu event candidates that are mostly signal, containing only 1 estimated background. Using this statistically compelling sample, we measure preliminary values of B(D+ to mu+ nu) = (3.5 +- 1.4 +- 0.6)*10^{-4}, and determine f_{D+} =(201+- 41+- 17) MeV.Comment: 17 pages postscript, also available through http://www.lns.cornell.edu/public/CONF/2004/, Presented at ICHEP Aug 16-22,2004, Beijing, Chin

    Starfire Optical Range 3.5-m telescope adaptive optical system

    Get PDF
    A 941 channel, 1500 Hertz frame rate adaptive optical (AO) system has been installed and tested in the coude path of the 3.5m telescope at the USAF Research Laboratory Starfire Optical Range. This paper describes the design and measured performance of the principal components comprising this system and present sample results from the first closed-loop test of the system on stars and an artificial source simulator
    corecore