71 research outputs found

    Unparticle effects on top quark rare decays

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    In this work we study the flavor changing neutral current(FCNC) decays of the top quark, t→cγt\to c\gamma and t→cgt\to c g. The Standard Model, predictions for the branching ratios of these decays are about ∼5×10−14\sim 5\times 10^{-14}, and ∼1×10−12\sim 1\times 10^{-12}, respectively. The recent study presented by the ATLAS Collaboration gives a sensitivity on these branching ratios about ∼10−5\sim 10^{-5} at %95 C.L. The parameter space of λ\lambda, Λ\Lambda, and dd where the branching ratios of t→cγt\to c\gamma and t→cgt\to c g decays exceed these predictions is obtained

    Unparticle physics effects in (Lambda_b -> Lambda + missing energy) processes

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    We study unparticle physics effects in (Lambda_b -> Lambda + missing energy) decay with polarized Λb\Lambda_b and Λ\Lambda baryons. The sensitivity of the branching ratio of this decay and polarizations of (Lambda_b) and (Lambda) baryons on the scale dimension d_U and effective cut-off parameter (Lambda_U) are discussed.Comment: 17 pages, 6 figure

    The G0 Experiment: Apparatus for Parity-Violating Electron Scattering Measurements at Forward and Backward Angles

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    In the G0 experiment, performed at Jefferson Lab, the parity-violating elastic scattering of electrons from protons and quasi-elastic scattering from deuterons is measured in order to determine the neutral weak currents of the nucleon. Asymmetries as small as 1 part per million in the scattering of a polarized electron beam are determined using a dedicated apparatus. It consists of specialized beam-monitoring and control systems, a cryogenic hydrogen (or deuterium) target, and a superconducting, toroidal magnetic spectrometer equipped with plastic scintillation and aerogel Cerenkov detectors, as well as fast readout electronics for the measurement of individual events. The overall design and performance of this experimental system is discussed.Comment: Submitted to Nuclear Instruments and Method

    Evolution and Prognostic Impact of Cardiac Damage After Aortic Valve Replacement

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    BACKGROUND The impact of aortic valve replacement (AVR) on progression/regression of extravalvular cardiac damage and its association with subsequent prognosis is unknown.OBJECTIVES The purpose of this study was to describe the evolution of cardiac damage post-AVR and its association with outcomes.METHODS Patients undergoing transcatheter or surgical AVR from the PARTNER (Placement of Aortic Transcatheter Valves) 2 and 3 trials were pooled and classified by cardiac damage stage at baseline and 1 year (stage 0, no damage; stage 1, left ventricular damage; stage 2, left atrial or mitral valve damage; stage 3, pulmonary vasculature or tricuspid valve damage; and stage 4, right ventricular damage). Proportional hazards models determined association between change in cardiac damage post-AVR and 2-year outcomes.RESULTS Among 1,974 patients, 121 (6.1%) were stage 0, 287 (14.5%) stage 1, 1,014 (51.4%) stage 2, 412 (20.9%) stage 3, and 140 (7.1%) stage 4 pre-AVR. Two-year mortality was associated with extent of cardiac damage at baseline and 1 year. Compared with baseline, cardiac damage improved inw15%, remained unchanged inw60%, and worsened in w25% of patients at 1 year. The 1-year change in cardiac damage stage was independently associated with mortality (adjusted HR for improvement: 0.49; no change: 1.00; worsening: 1.95; P = 0.023) and composite of death or heart failure hospitalization (adjusted HR for improvement: 0.60; no change: 1.00; worsening: 2.25; P < 0.001) at 2 years.CONCLUSIONS In patients undergoing AVR, extent of extravalvular cardiac damage at baseline and its change at 1 year have important prognostic implications. These findings suggest that earlier detection of aortic stenosis and intervention before development of irreversible cardiac damage may improve global cardiac function and prognosis. (C) 2022 by the American College of Cardiology Foundation
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