425 research outputs found

    Is the Top Quark Really Heavier than the WW Boson?

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    Scalar induced top decays may drastically suppress B(t→ℓΜ+jet)B(t\to \ell\nu + jet) and still hide the top below MWM_W. The ppˉp\bar p collider experiments should enlarge the scope and study the mt−B(t→ℓΜj)m_t - B(t\to\ell\nu j) plane. Specific model signatures such as t→ch0→cbbˉt\to ch^0\to cb\bar b (multiple high pTp_T bb-jets) and t→bH+→bcsˉt\to bH^+\to bc\bar s, bτ+Îœb\tau^+\nu (with $B(t\to b\tau\nu) \ \raisebox{-.5ex}{\rlap{∌\sim}} \raisebox{.4ex}{<<}\ 1/3)shouldbeexplored.Withoutrulingoutthesepossibilities,isolatedleptonsignalsinthefuturemightactuallybeduetothe4thgeneration) should be explored. Without ruling out these possibilities, isolated lepton signals in the future might actually be due to the 4th generation t^\primeor or b^\prime$ quark, while top quark and toponium physics could still turn up at LEP-II.Comment: 11 pages (RevTex), 3 figures (not included), NTUTH-93-0

    Analysis of proteomic profiles and functional properties of human peripheral blood myeloid dendritic cells, monocyte-derived dendritic cells and the dendritic cell-like KG-1 cells reveals distinct characteristics

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    Important proteomic and functional differences between peripheral blood myeloid dendritic cells, monocyte-derived dendritic cells (moDC) and KG-1 cells have been identified

    Top-ology

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    Extended version of an article on top-quark physics, to appear in the May 1997 issue of Physics Today.Comment: 24 pages, 5 figures, LaTeX2e + BoxedEPS

    Kinematic Effects in Radiative Quarkonia Decays

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    Non-relativistic QCD (NRQCD) predicts colour octet contributions to be significant not only in many production processes of heavy quarkonia but also in their radiative decays. We investigate the photon energy distributions in these processes in the endpoint region. There the velocity expansion of NRQCD breaks down which requires a resummation of an infinite class of colour octet operators to so-called shape functions. We model these non-perturbative functions by the emission of a soft gluon cluster in the initial state. We found that the spectrum in the endpoint region is poorly understood if the values for the colour octet matrix elements are taken as large as indicated from NRQCD scaling rules. Therefore the endpoint region should not be taken into account for a fit of the strong coupling constant at the scale of the heavy quark mass.Comment: LaTeX, 17 pages, 5 figures. The complete paper is also available via the www at http://www-ttp.physik.uni-karlsruhe.de/Preprints

    Use of an amplatzer vascular plug in embolization of a pulmonary artery aneurysm in a case of hughes-stovin syndrome: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Hughes-Stovin syndrome is a rare condition characterized by peripheral deep venous thrombosis accompanied by single or multiple pulmonary arterial aneurysms. The limited number of cases has precluded controlled studies of the management of pulmonary artery aneurysms, which usually cause massive hemoptysis leading to death. This is the first report of a new endovascular treatment of a single large pulmonary arterial aneurysm.</p> <p>Case presentation</p> <p>An 18-year-old Caucasian man was referred to our department with recurrent severe hemoptysis. His medical history included Hughes-Stovin syndrome diagnosed during a recent hospital admission. The patient was initially treated with corticosteroids. Because of his recurrent hemoptysis, we decided to embolize a 3.5 cm pulmonary arterial aneurysm using an Amplatzer Vascular Plug. The procedure was not complicated, and the patient's post-intervention course was uneventful. The patient has remained free from any complications of the embolization 36 months after the procedure.</p> <p>Conclusion</p> <p>Percutaneous embolization of a single large pulmonary artery aneurysm with an Amplatzer Vascular Plug in a patient with Hughes-Stovin syndrome is a less invasive procedure that represents the best multidisciplinary approach in treating these patients.</p

    Bottomonium and Drell-Yan production in p-A collisions at 450 GeV

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    The NA50 Collaboration has measured heavy-quarkonium production in p-A collisions at 450 GeV incident energy (sqrt(s) = 29.1 GeV). We report here results on the production of the Upsilon states and of high-mass Drell-Yan muon pairs (m > 6 GeV). The cross-section at midrapidity and the A-dependence of the measured yields are determined and compared with the results of other fixed-target experiments and with the available theoretical estimates. Finally, we also address some issues concerning the transverse momentum distributions of the measured dimuons.Comment: 18 pages, 9 figures, to be published in Phys. Lett.

    Measurement of the Top Quark Pair Production Cross Section in pbarp Collisions

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    We present a measurement of the ttbar production cross section in ppbar collisions at root(s) = 1.8TeV by the D0 experiment at the Fermilab Tevatron. The measurement is based on data from an integrated luminosity of approximately 125 pb^-1 accumulated during the 1992-1996 collider run. We observe 39 ttbar candidate events in the dilepton and lepton+jets decay channels with an expected background of 13.7+-2.2 events. For a top quark mass of 173.3GeV/c^2, we measure the ttbar production cross section to be 5.5+-1.8 pb.Comment: 11 pages with 3 encapsulated PostScript figures and 2 PostScript table included in the body of the articl

    New Petro‐aggression in the Middle East: Saudi Arabia in the Spotlight

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    That hydrocarbon abundance may lead to more violence is an established truism in the literature on the resource curse. Looking at the Middle East, however, the literature relates bellicose state behaviour entirely to oil-producing revolutionary republics. Instead, dynastic monarchies are claimed to be the more peacefully behaving actors. Current developments turn this conclusion upside down, however. Since 2015 at the latest, the foreign policy of Saudi Arabia, the leading monarchy in the Middle East, has transformed from multi-dependence to petro-aggression. By discussing this striking transformation, the paper puts forward a framework looking at the interaction of three crucial dimensions: first, the decreasing power projection towards the Middle East by the United States, the decade-long hegemon, due to gradual changes in world energy markets and war fatigue at home; second, the lasting fiscal potency of the Saudi regime; and, third, the personalization of the Saudi monarchy under King Salman as a historically contingent result of transferring power to the generation of Ibn Saud's grandsons
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