8,965 research outputs found

    Constraints on the parameters of the CKM matrix by End 1998

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    A review of the current status of the Cabibbo-Kobayashi-Maskawa matrix (CKM) is presented. This paper is an update of the results published in [1]. The experimental constraints imposed by the measurements of \epsilon_K, V_{ub}/V_{cb}, \Delta m_d and from the limit on \Delta m_d are used. Values of the constraints and of the parameters entering into the constraints, which restrict the range of the \bar{\rho} and \bar{\eta} parameters, include recent measurements presented at 1998 Summer Conferences and progress obtained by lattice QCD collaborations. The results are: \bar{\rho}=0.202 ^{+0.053}_{-0.059},\bar{\eta}=0.340 \pm 0.035, from which the angles \alpha, \beta and \gamma of the unitarity triangle are inferred : \sin 2 \alpha = -0.26 ^{+ 0.29}_{-0.28} ,\sin 2 \beta = 0.725 ^{+0.050}_{-0.060} ,\gamma= (59.5^{+8.5}_{-7.5})^{\circ}. Without using the constraint from \epsilon_K, \sin 2 \beta has been obtained: \sin 2 \beta = 0.72 ^{+0.07}_{-0.11}. Several external measurements or theoretical inputs have been removed, in turn, from the constraints and their respective probability density functions have been obtained. Central values and uncertainties on these quantities have been compared with actual measurements or theoretical evaluations. In this way it is possible to quantify the importance of the different measurements and the coherence of the Standard Model scenario for CP violation. An important result is that \Delta m_s is expected to be between [12.0-17.6] ps^{-1} with 68% C.L. and <20 ps^{-1} at 95% C.L. Finally relations between the CKM parameters and the quark masses are examined within a given model.Comment: 26 page

    Sub-millimeter nuclear medical imaging with high sensitivity in positron emission tomography using beta-gamma coincidences

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    We present a nuclear medical imaging technique, employing triple-gamma trajectory intersections from beta^+ - gamma coincidences, able to reach sub-millimeter spatial resolution in 3 dimensions with a reduced requirement of reconstructed intersections per voxel compared to a conventional PET reconstruction analysis. This 'γ\gamma-PET' technique draws on specific beta^+ - decaying isotopes, simultaneously emitting an additional photon. Exploiting the triple coincidence between the positron annihilation and the third photon, it is possible to separate the reconstructed 'true' events from background. In order to characterize this technique, Monte-Carlo simulations and image reconstructions have been performed. The achievable spatial resolution has been found to reach ca. 0.4 mm (FWHM) in each direction for the visualization of a 22Na point source. Only 40 intersections are sufficient for a reliable sub-millimeter image reconstruction of a point source embedded in a scattering volume of water inside a voxel volume of about 1 mm^3 ('high-resolution mode'). Moreover, starting with an injected activity of 400 MBq for ^76Br, the same number of only about 40 reconstructed intersections are needed in case of a larger voxel volume of 2 x 2 x 3~mm^3 ('high-sensitivity mode'). Requiring such a low number of reconstructed events significantly reduces the required acquisition time for image reconstruction (in the above case to about 140 s) and thus may open up the perspective for a quasi real-time imaging.Comment: 17 pages, 5 figutes, 3 table

    A detector of small harmonic displacements based on two coupled microwave cavities

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    The design and test of a detector of small harmonic displacements is presented. The detector is based on the principle of the parametric conversion of power between the resonant modes of two superconducting coupled microwave cavities. The work is based on the original ideas of Bernard, Pegoraro, Picasso and Radicati, who, in 1978, suggested that superconducting coupled cavities could be used as sensitive detectors of gravitational waves, and on the work of Reece, Reiner and Melissinos, who, {in 1984}, built a detector of this kind. They showed that an harmonic modulation of the cavity length l produced an energy transfer between two modes of the cavity, provided that the frequency of the modulation was equal to the frequency difference of the two modes. They achieved a sensitivity to fractional deformations of dl/l~10^{-17} Hz^{-1/2}. We repeated the Reece, Reiner and Melissinos experiment, and with an improved experimental configuration and better cavity quality, increased the sensitivity to dl/l~10^{-20} Hz^{-1/2}. In this paper the basic principles of the device are discussed and the experimental technique is explained in detail. Possible future developments, aiming at gravitational waves detection, are also outlined.Comment: 28 pages, 12 eps figures, ReVteX. \tightenlines command added to reduce number of pages. The following article has been accepted by Review of Scientific Instruments. After it is published, it will be found at http://link.aip.org/link/?rs

    2000 CKM-Triangle Analysis A Critical Review with Updated Experimental Inputs and Theoretical Parameters

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    Within the Standard Model, a review of the current determination of the sides and angles of the CKM unitarity triangle is presented, using experimental constraints from the measurements of |\epsilon_K|, |V_{ub}/V_{cb}|, \Delta m_d and from the limit on \Delta m_s, available in September 2000. Results from the experimental search for {B}^0_s-\bar{B}^0_s oscillations are introduced in the present analysis using the likelihood. Special attention is devoted to the determination of the theoretical uncertainties. The purpose of the analysis is to infer regions where the parameters of interest lie with given probabilities. The BaBar "95 %, C.L. scanning" method is also commented.Comment: 44 pages (revised version

    Metabolism of ticagrelor in patients with acute coronary syndromes.

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    © The Author(s) 2018Ticagrelor is a state-of-the-art antiplatelet agent used for the treatment of patients with acute coronary syndromes (ACS). Unlike remaining oral P2Y12 receptor inhibitors ticagrelor does not require metabolic activation to exert its antiplatelet action. Still, ticagrelor is extensively metabolized by hepatic CYP3A enzymes, and AR-C124910XX is its only active metabolite. A post hoc analysis of patient-level (n = 117) pharmacokinetic data pooled from two prospective studies was performed to identify clinical characteristics affecting the degree of AR-C124910XX formation during the first six hours after 180 mg ticagrelor loading dose in the setting of ACS. Both linear and multiple regression analyses indicated that ACS patients presenting with ST-elevation myocardial infarction or suffering from diabetes mellitus are more likely to have decreased rate of ticagrelor metabolism during the acute phase of ACS. Administration of morphine during ACS was found to negatively influence transformation of ticagrelor into AR-C124910XX when assessed with linear regression analysis, but not with multiple regression analysis. On the other hand, smoking appears to increase the degree of ticagrelor transformation in ACS patients. Mechanisms underlying our findings and their clinical significance warrant further research.Peer reviewedFinal Published versio

    Microwave apparatus for gravitational waves observation

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    In this report the theoretical and experimental activities for the development of superconducting microwave cavities for the detection of gravitational waves are presented.Comment: 42 pages, 28 figure

    A Fast Tracking Algorithm for the ATLAS Level 2 Trigger

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    A set of conceptually simple and robust algorithms for fast pattern recognition and track reconstruction using 3D space points developed for the ATLAS Level 2 (LVL2) Trigger at the LHC is presented. Results on execution time and physics performance demonstrating the effectiveness of this approach in a demanding, online trigger environment are presented. Both this strategy and a complimentary lookup table based strategy provided results appearing in the recent ATLAS High-Level Trigger, Data Acquisition and Controls Technical Design Report and were successfully implemented online during data taking for the recent ATLAS combined test beam
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