9,910 research outputs found

    Heavy Quark Physics From Lattice QCD

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    We review the application of lattice QCD to the phenomenology of b- and c-quarks. After a short discussion of the lattice techniques used to evaluate hadronic matrix elements and the corresponding systematic uncertainties, we summarise results for leptonic decay constants, B--Bbar mixing, semileptonic and rare radiative decays. A discussion of the determination of heavy quark effective theory parameters is followed by an explanation of the difficulty in applying lattice methods to exclusive nonleptonic decays.Comment: 52 pages LaTeX with 10 eps files. Requires: hfsprocl.sty (included) plus axodraw.sty, rotating.sty and array.sty. To appear in Heavy Flavours (2nd edition) edited by A J Buras and M Lindner (World Scientific, Singapore). Revised version corrects typo in axis labelling of Fig 1

    Galactic Archaeology and Minimum Spanning Trees

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    Chemical tagging of stellar debris from disrupted open clusters and associations underpins the science cases for next-generation multi-object spectroscopic surveys. As part of the Galactic Archaeology project TraCD (Tracking Cluster Debris), a preliminary attempt at reconstructing the birth clouds of now phase-mixed thin disk debris is undertaken using a parametric minimum spanning tree (MST) approach. Empirically-motivated chemical abundance pattern uncertainties (for a 10-dimensional chemistry-space) are applied to NBODY6-realised stellar associations dissolved into a background sea of field stars, all evolving in a Milky Way potential. We demonstrate that significant population reconstruction degeneracies appear when the abundance uncertainties approach 0.1 dex and the parameterised MST approach is employed; more sophisticated methodologies will be required to ameliorate these degeneracies.Comment: To appear in "Multi-Object Spectroscopy in the Next Decade: Big Questions, Large Surveys and Wide Fields"; Held: Santa Cruz de La Palma, Canary Islands, Spain, 2-6 Mar 2015; ed. I Skillen & S. Trager; ASP Conference Series (Figures now optimised for B&W printing

    Vibrational relaxation measurements in CO2 USING an induced fluorescence technique

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    Vibrational relaxation measurements in carbon dioxide using induced infrared fluorescence techniqu

    Highly Ionized High-Velocity Clouds toward PKS 2155-304 and Markarian 509

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    To gain insight into four highly ionized high-velocity clouds (HVCs) discovered by Sembach et al. (1999), we have analyzed data from the Hubble Space Telescope (HST) and Far Ultraviolet Spectroscopic Explorer (FUSE) for the PKS 2155-304 and Mrk 509 sight lines. We measure strong absorption in OVI and column densities of multiple ionization stages of silicon (SiII/III/IV) and carbon (CII/III/IV). We interpret this ionization pattern as a multiphase medium that contains both collisionally ionized and photoionized gas. Toward PKS 2155-304, for HVCs at -140 and -270 km/s, respectively, we measure logN(OVI)=13.80+/-0.03 and log N(OVI)=13.56+/-0.06; from Lyman series absorption, we find log N(HI)=16.37^(+0.22)_(-0.14) and 15.23^(+0.38)_(-0.22). The presence of high-velocity OVI spread over a broad (100 km/s) profile, together with large amounts of low-ionization species, is difficult to reconcile with the low densities, n=5x10^(-6) cm^(-3), in the collisional/photoionization models of Nicastro et al. (2002), although the HVCs show a similar relation in N(SiIV)/N(CIV) versus N(CII)/N(CIV) as high-z intergalactic clouds. Our results suggest that the high-velocity OVI in these absorbers do not necessarily trace the WHIM, but instead may trace HVCs with low total hydrogen column density. We propose that the broad high-velocity OVI absorption arises from shock ionization, at bowshock interfaces produced from infalling clumps of gas with velocity shear. The similar ratios of high ions for HVC Complex C and these highly ionized HVCs suggest a common production mechanism in the Galactic halo.Comment: 38 pages, including 10 figures. ApJ, 10 April, 2004. Replaced with accepted versio

    Advantages and disadvantages of encouraging consumerist notions of healthcare at two minor injury units: results of a multiple embedded case study.

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    Over the past four decades, UK Governments have moved towards an increasingly pro-market model of health-care provision. Under this system patients are not only encouraged, but expected, to take increasing responsibility for health-care decision-making and the risks that it might entail. This article investigate how and why patients make choices about their health-care and how service providers help facilitate this. Between October 2014 and May 2015, the researcher was embedded as an emergency nurse practitioner at two minor injury units in order to undertake direct and participant observation. During this time, 40 patients, 17 service providers and 1 senior manager also consented to semi-structured interview. The findings suggest that patients should continue to be encouraged to make decisions about their health-care, but only if they feel confident to do so. The challenge for service providers is to recognise when this is/not appropriate and tailor interaction accordingly
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