Distribution, Movement and Abundance of Polar Bears in Lancaster Sound, Northwest Territories

Mark-recapture studies show that polar bears are distributed at varying densities throughout Lancaster Sound during winter and spring. Major concentrations occur along the north and south coasts and the transverse floe edge at the mouth of the sound. As the ice melts, some bears move west whereas others move to nearby land areas. There is some evidence that as the ice forms, polar bears return from their summer locations to eastern Lancaster Sound. Polar bears of Lancaster Sound are part of the larger population whose western range extends to Barrow Strait, Prince Regent Inlet, Wellington Channel and Jones Sound. The southern and eastern range limits are unknown although this population may extend at least to Clyde River on northeastern Baffin Island and probably to Greenland. Maternity denning appears to be widespread over the study area probably because of the abundance of suitable habitat. We estimated a population of 1031 ± 236 polar bears in Lancaster Sound during 1979: however, more estimates are needed to determine if this relatively high number is normal for the area.Key words: polar bear, distribution, movement, abundance, Baffin Bay, Lancaster Sound, summer retreat, dennin

Productivity, Survival, and Movements of Female Moose in a Low-density Population, Northwest Territories, Canada

Moose (Alces alces andersoni) occur at low density (140-160 moose/1000 sq km) and are the most important game animal in much of the Mackenzie Valley, western Northwest Territories. Productivity and survival of 30 female moose (>=1.5 yr.) were studied from November 1985 through November 1988. Twenty-nine of these moose were radio-tracked for a total of 1039 relocations. Pregnancy rates were 96% for adult and 40% for yearling females. Most females returned to the same restricted area to calve each year. Mean newborn calf:female ratio and twinning rates were 1.2:1 and 31%, respectively. Mean annual female survival rate was 85%. Annual calf survival was high and stable (44±0.02%). Individual total home range size varied from 40 sq km to 942 sq km. Mean home range size for 29 moose was 174±31 sq km and 202±59 sq km for the 14 moose radio-tracked the entire three years of study. Fall home ranges were twice the size of winter and summer home ranges; seasonal ranges overlapped widely, indicating that these moose were non-migratory.Key words: moose, low density, productivity, movements, Mackenzie Valley, Northwest TerritoriesL'orignal (Alces alces andersoni) est présent à faible densité (140-160 orignaux/1000 km²) et constitue le gibier le plus important dans la plupart de la vallée du Mackenzie, à l'ouest des Territoires du Nord-Ouest. On a étudié la productivité et le taux de survie de 30 orignaux femelles (<= 1,5 ans) de novembre 1985 à novembre 1988. Vingt-neuf de ces orignaux ont été suivis par radio sur un total de 1039 déplacements. Les taux de gestation étaient de 96 p. cent pour les adultes et de 40 p. cent pour les femelles d'un an. La plupart des femelles retournaient chaque année mettre bas dans la même zone restreinte. Le rapport moyen mâle/femelle parmi les nouveau-nés était de 1,2 pour 1, et le pourcentage de jumeaux était de 30 p. cent. Le taux de survie annuel moyen des femelles était de 85 p. cent. Le taux de survie annuel des veaux était élevé et stable (44 ± 0,02 p. cent). Le territoire individuel total variait de 40 à 942 km². Le territoire moyen mesurait 174 ± 31 km² pour l'ensemble des 29 orignaux, et 202 ± 59 km² pour les 14 orignaux suivis par radio du début à la fin de la période triennale d'étude. Les territoires étaient deux fois plus étendus en automne qu'en hiver ou en été; les territoires saisonniers se recoupaient largement, ce qui indique que ces orignaux n'étaient pas migratoires.Mots clés: orignal, faible densité, productivité, mouvements, vallée du Mackenzie, Territoires du Nord-Ouest&nbsp

Erratum: "On the Use of Field RR Lyrae as Galactic Probes. V. Optical and Radial Velocity Curve Templates" (2021, ApJ, 919, 85)

[no abstract available

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters

Measurement of the inclusive isolated prompt photon cross-section in pp collisions at sqrt(s)= 7 TeV using 35 pb-1 of ATLAS data

A measurement of the differential cross-section for the inclusive production of isolated prompt photons in pp collisions at a center-of-mass energy sqrt(s) = 7 TeV is presented. The measurement covers the pseudorapidity ranges |eta|<1.37 and 1.52<=|eta|<2.37 in the transverse energy range 45<=E_T<400GeV. The results are based on an integrated luminosity of 35 pb-1, collected with the ATLAS detector at the LHC. The yields of the signal photons are measured using a data-driven technique, based on the observed distribution of the hadronic energy in a narrow cone around the photon candidate and the photon selection criteria. The results are compared with next-to-leading order perturbative QCD calculations and found to be in good agreement over four orders of magnitude in cross-section.Comment: 7 pages plus author list (18 pages total), 2 figures, 4 tables, final version published in Physics Letters

Measurement of D*+/- meson production in jets from pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

This paper reports a measurement of D*+/- meson production in jets from proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV at the CERN Large Hadron Collider. The measurement is based on a data sample recorded with the ATLAS detector with an integrated luminosity of 0.30 pb^-1 for jets with transverse momentum between 25 and 70 GeV in the pseudorapidity range |eta| < 2.5. D*+/- mesons found in jets are fully reconstructed in the decay chain: D*+ -> D0pi+, D0 -> K-pi+, and its charge conjugate. The production rate is found to be N(D*+/-)/N(jet) = 0.025 +/- 0.001(stat.) +/- 0.004(syst.) for D*+/- mesons that carry a fraction z of the jet momentum in the range 0.3 < z < 1. Monte Carlo predictions fail to describe the data at small values of z, and this is most marked at low jet transverse momentum.Comment: 10 pages plus author list (22 pages total), 5 figures, 1 table, matches published version in Physical Review