6,578 research outputs found

    Direct Determination of the CKM Matrix from Decays of W Bosons and Top Quarks at High Energy e+e- Colliders

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    At proposed high energy linear e+e- colliders a large number of W bosons and top quarks will be produced. We evaluate the potential precision to which the decay branching ratios into the various quark species can be measured, implying also the determination of the respective CKM matrix elements. Crucial is the identification of the individual quark flavours, which can be achieved independent of QCD models. For transitions involving up quarks the accuracy is of the same order of magnitude as has been reached in hadron decays. We estimate that for charm transitions a precision can be reached that is superior to current and projected traditional kinds of measurements. The t->b determination will be significantly improved, and for the first time a direct measurement of the t->s transition can be made. In all cases such a determination is complementary to the traditional way of extracting the CKM matrix elements.Comment: 28 pages, 4 figures; Submitted to Eur. Phys. J.

    A new method to determine the electroweak couplings of individual light flavours at LEP

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    A method is presented for determining the yields and properties of individual light quark flavours in Z0Z^0 decays that is essentially free of detailed assumptions about hadronisation. The method uses an equation system with the number of events which are single and double tagged by high energy hadrons as inputs. In addition, SU(2) isospin symmetry and the flavour independence of QCD are used to derive general relations between hadron production from the various primary light quarks. Assuming the branching fractions RqR_q of the Z0Z^0 into down and strange quarks to be the same, five million hadronic Z0Z^0 decays may allow a precisions of őī(Rd=Rs)/(Rd=Rs)‚ąľ0.05\delta{(R_d=R_s)}/(R_d=R_s)\sim{0.05} and őīAFB(d=s)‚ąľőīAFB(u)‚ąľ0.015\delta A_{FB}(d=s) \sim \delta A_{FB}(u) \sim{0.015} for the corresponding asymmetries. The method can be extended to include somewhat more model dependent symmetries of hadron production, which then allows the electroweak observables for each of the individual light quarks to be determined

    A Measurement of Strange Baryon Production and Correlations in Hadronic Z0^{0} Decays

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    Why do men self-harm? A literature review

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    This critical review developed and analysed two key strands. One strand examined the reasons why men self-harm; the other examined effective ways to educate staff about self-harm. These strands were interweaved to develop an in-depth and informative review to help educate and inform staff who work with and support men who self-harm. A systematic search strategy was conducted to find primary research articles for analysis and evaluation. Three key themes emerged: interpersonal relationships; attitudes and educating staff. This review recommends that staff should be encouraged to change their behaviour and view themselves and their relationships differently. This can have a positive impact on developing and maintaining therapeutic relationships

    The GREAT triggerless total data readout method

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    Recoil decay tagging (RDT) is a very powerful method for the spectroscopy of exotic nuclei. RDT is a delayed coincidence technique between detectors usually at the target position and at the focal plane of a spectrometer. Such measurements are often limited by dead time. This paper describes a novel triggerless data acquisition method, which is being developed for the Gamma Recoil Electron Alpha Tagging (GREAT) spectrometer, that overcomes this limitation by virtually eliminating dead time. Our solution is a total data readout (TDR) method where all channels run independently and are associated in software to reconstruct events. The TDR method allows all the data from both target position and focal plane to be collected with practically no dead-time losses. Each data word is associated with a timestamp generated from a global 100-MHz clock. Events are then reconstructed in real time in the event builder using temporal and spatial associations defined by the physics of the experimen

    Health of War-Affected Karen Adults 5 Years Post-Resettlement

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    Background: An estimated 140 000 refugees from Burma have resettled to the USA since 2009, comprising 21% of total resettlement in the USA over the last decade. Our objective was to describe patterns of longitudinal health outcomes in a cohort of Karen refugees resettled in the USA for 5 years, and to translate these findings to a primary healthcare context. Methods: The study was a retrospective cohort study focused on the analysis of the first 5 years of electronic health records of a sample of 143 Karen refugees who were initially resettled between May 2011 and May 2013. Results: Through descriptive, inferential and survival statistics, we described patterns of retention in primary care, biometric trends, condition prevalence and survival probabilities. Highest prevalence health conditions documented at any point in the 5-year period included diagnoses or symptoms associated with pain (52%); gastrointestinal disturbance (41%); metabolic disorder (41%); infectious process (34%); mental health condition (31%) and central nervous system disorder (24%). Conclusions: This study is the first retrospective longitudinal analysis of patterns of health in Karen refugees originating from Burma and resettled to the USA. Findings identified in the 5-year, the post-resettlement period provided important clinical insights into the health trajectories of war-affected populations. Burden of illness was high although results did not demonstrate the extent of trauma-associated physical health conditions reported in the literature. Indicators such as significant increases in body mass index (BMI), the overall prevalence of dyslipidaemia and others suggested that the cohort may be exhibiting an early trajectory towards the development of these conditions. Authors summarize potential protective factors experienced by the cohort that promoted aspects of health frequently challenged in forced migration

    The commissioning of CMS sites: improving the site reliability

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    The computing system of the CMS experiment works using distributed resources from more than 60 computing centres worldwide. These centres, located in Europe, America and Asia are interconnected by the Worldwide LHC Computing Grid. The operation of the system requires a stable and reliable behaviour of the underlying infrastructure. CMS has established a procedure to extensively test all relevant aspects of a Grid site, such as the ability to efficiently use their network to transfer data, the functionality of all the site services relevant for CMS and the capability to sustain the various CMS computing workflows at the required scale. This contribution describes in detail the procedure to rate CMS sites depending on their performance, including the complete automation of the program, the description of monitoring tools, and its impact in improving the overall reliability of the Grid from the point of view of the CMS computing system

    CMS Connect

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    The CMS experiment collects and analyzes large amounts of data coming from high energy particle collisions produced by the Large Hadron Collider (LHC) at CERN. This involves a huge amount of real and simulated data processing that needs to be handled in batch-oriented platforms. The CMS Global Pool of computing resources provide +100K dedicated CPU cores and another 50K to 100K CPU cores from opportunistic resources for these kind of tasks and even though production and event processing analysis workflows are already managed by existing tools, there is still a lack of support to submit final stage condor-like analysis jobs familiar to Tier-3 or local Computing Facilities users into these distributed resources in an integrated (with other CMS services) and friendly way. CMS Connect is a set of computing tools and services designed to augment existing services in the CMS Physics community focusing on these kind of condor analysis jobs. It is based on the CI-Connect platform developed by the Open Science Grid and uses the CMS GlideInWMS infrastructure to transparently plug CMS global grid resources into a virtual pool accessed via a single submission machine. This paper describes the specific developments and deployment of CMS Connect beyond the CI-Connect platform in order to integrate the service with CMS specific needs, including specific Site submission, accounting of jobs and automated reporting to standard CMS monitoring resources in an effortless way to their users
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