629 research outputs found

    Final State Interactions in Hypernuclear Decay

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    We present an update of the One-Meson-Exchange (OME) results for the weak decay of s- and p-shell hypernuclei (Ref. Phys. Rev. C {\bf 56}, 339 (1997)), paying special attention to the role played by final state interactions between the emitted nucleons. The present study also corrects for a mistake in the inclusion of the KK and KK^* exchange mechanisms, which substantially increases the ratio of neutron-induced to proton-induced transitions, Γn/Γp\Gamma_n/\Gamma_p. With the most up-to-date model ingredients, we find that the OME approach is able to describe very satisfactorily most of the measured observables, including the ratio Γn/Γp\Gamma_n/\Gamma_p.Comment: 20 pages, 2 eps figure

    Novel Weak Decays in Doubly Strange Systems

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    The strangeness-changing (ΔS=1\Delta S = 1) weak baryon-baryon interaction is studied through the nonmesonic weak decay of double-Λ\Lambda hypernuclei. Besides the usual nucleon-induced decay ΛNNN\Lambda N \to N N we discuss novel hyperon-induced decay modes ΛΛΛN\Lambda \Lambda \to \Lambda N and ΛΛΣN\Lambda \Lambda \to \Sigma N. These reactions provide unique access to the exotic ΛΛ\Lambda \LambdaK and ΛΣ\Lambda \SigmaK vertices which place new constraints on Chiral Pertubation Theory (χ\chiPT) in the weak SU(3) sector. Within a meson-exchange framework, we use the pseudoscalar π,η,K\pi,\eta,K octet for the long-range part while parametrizing the short-range part through the vector mesons ρ,ω,K\rho, \omega, K^*. Realistic baryon-baryon forces for the S=0,1S=0,-1 and -2 sectors account for the strong interaction in the initial and final states. For ΛΛ6^6_{\Lambda \Lambda}He the new hyperon-induced decay modes account for up to 4% of the total nonmesonic decay rate. Predictions are made for all possible nonmesonic decay modes.Comment: 19 pages, 2 ps figures, 9 table

    Magnetic moments of antidecuplet pentaquarks

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    We analyze the magnetic moment of the exotic pentaquarks of the flavor antidecuplet in the constituent quark model for the case in which the ground state is in an orbital L(p)=0(+) or a L(p)=1(-) state. We derive sum rules for the magnetic moments. The magnetic moment of the Theta(1540) is found to be 0.38, 0.09 and 1.05 mu_N for J(p)=1/2(-), 1/2(+) and 3/2(+), respectively, which is compared with the results obtained in other approaches.Comment: 15 pages, 1 figure, 3 tables. Revised version, extended introduction and discussion, accepted for publication in Physics Letters

    Multi-site performance evaluation of the Alinity m Molecular assay for quantifying Epstein-Barr virus DNA in plasma samples

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    Detection and monitoring of acute infection or reactivation of Epstein-Barr virus (EBV) are critical for treatment decision-making and to reduce the risk of EBV-related malignancies and other associated diseases in immunocompromised individuals. The analytical and clinical performance of the Alinity m EBV assay was evaluated at two independent study sites; analytical performance was assessed by evaluating precision with a commercially available 5-member EBV verification panel, while the clinical performance of the Alinity m EBV assay was compared to the RealTime EBV assay and a laboratory-developed test (LDT) as the routine test of record (TOR). Analytical analysis demonstrated standard deviation (SD) between 0.08 and 0.13 Log IU/mL. A total of 300 remnant plasma specimens were retested with the Alinity m EBV assay, and results were compared to those of the TOR at the respective study sites (n = 148 with the RealTime EBV assay and n = 152 with the LDT EBV assay). Agreement between Alinity m EBV and RealTime EBV or LDT EBV assays had kappa values of 0.88 and 0.84, respectively, with correlation coefficients r of 0.956 and 0.912, while the corresponding observed mean bias was -0.02 and -0.19 Log IU/mL. The Alinity m EBV assay had a short median onboard turnaround time of 2:40 h. Thus, the Alinity m system can shorten the time to results and, therefore, to therapy.Molecular basis of virus replication, viral pathogenesis and antiviral strategie

    Fluctuations as probe of the QCD phase transition and freeze-out in heavy ion collisions at LHC and RHIC

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    We discuss the relevance of higher order moments of net baryon number fluctuations for the analysis of freeze-out and critical conditions in heavy ion collisions at LHC and RHIC. Using properties of O(4) scaling functions, we discuss the generic structure of these higher moments at vanishing baryon chemical potential and apply chiral model calculations to explore their properties at non-zero baryon chemical potential. We show that the ratios of the sixth to second and eighth to second order moments of the net baryon number fluctuations change rapidly in the transition region of the QCD phase diagram. Already at vanishing baryon chemical potential they deviate considerably from the predictions of the hadron resonance gas model which reproduce the second to fourth order moments of the net proton number fluctuations at RHIC. We point out that the sixth order moments of baryon number and electric charge fluctuations remain negative at the chiral transition temperature. Thus, they offer the possibility to probe the proximity of the thermal freeze-out to the crossover line.Comment: 24 pages, 12 EPS files, revised version, to appear in EPJ

    Estimating cut points: A simple method for new wearables

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    Wearable technology is readily available for continuous assessment due to a growing number of commercial devices with increased data capture capabilities. However, many commercial devices fail to support suitable parameters (cut points) derived from the literature to help quantify physical activity (PA) due to differences in manufacturing. A simple metric to estimate cut points for new wearables is needed to aid data analysis. Objective: The purpose of this pilot study was to investigate a simple methodology to determine cut points based on ratios between sedentary behaviour (SB) and PA intensities for a new wrist worn device (PRO-Diary™) by comparing its output to a validated and well characterised ‘gold standard’ (ActiGraph™). Study design: Twelve participants completed a semi-structured (four-phase) treadmill protocol encompassing SB and three PA intensity levels (light, moderate, vigorous). The outputs of the devices were compared accounting for relative intensity. Results: Count ratios (6.31, 7.68, 4.63, 3.96) were calculated to successfully determine cut-points for the new wrist worn wearable technology during SB (0–426) as well as light (427–803), moderate (804–2085) and vigorous (≥2086) activities, respectively. Conclusion: Our findings should be utilised as a primary reference for investigations seeking to use new (wrist worn) wearable technology similar to that used here (i.e., PRO-Diary™) for the purposes of quantifying SB and PA intensities. The utility of count ratios may be useful in comparing devices or SB/PA values estimated across different studies. However, a more robust examination is required for different devices, attachment locations and on larger/diverse cohorts

    A conjecture on Exceptional Orthogonal Polynomials

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    Exceptional orthogonal polynomial systems (X-OPS) arise as eigenfunctions of Sturm-Liouville problems and generalize in this sense the classical families of Hermite, Laguerre and Jacobi. They also generalize the family of CPRS orthogonal polynomials. We formulate the following conjecture: every exceptional orthogonal polynomial system is related to a classical system by a Darboux-Crum transformation. We give a proof of this conjecture for codimension 2 exceptional orthogonal polynomials (X2-OPs). As a by-product of this analysis, we prove a Bochner-type theorem classifying all possible X2-OPS. The classification includes all cases known to date plus some new examples of X2-Laguerre and X2-Jacobi polynomials

    Cryptanalysis of MORUS

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    Item does not contain fulltextAdvances in Cryptology - ASIACRYPT 2018 - 24th International Conference on the Theory and Application of Cryptology and Information Security, Brisbane, QLD, Australia, December 2-

    Helicity Analysis of Semileptonic Hyperon Decays Including Lepton Mass Effects

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    Using the helicity method we derive complete formulas for the joint angular decay distributions occurring in semileptonic hyperon decays including lepton mass and polarization effects. Compared to the traditional covariant calculation the helicity method allows one to organize the calculation of the angular decay distributions in a very compact and efficient way. In the helicity method the angular analysis is of cascade type, i.e. each decay in the decay chain is analyzed in the respective rest system of that particle. Such an approach is ideally suited as input for a Monte Carlo event generation program. As a specific example we take the decay Ξ0Σ++l+νˉl\Xi^0 \to \Sigma^+ + l^- + \bar{\nu}_l (l=e,μl^-=e^-, \mu^-) followed by the nonleptonic decay Σ+p+π0\Sigma^+ \to p + \pi^0 for which we show a few examples of decay distributions which are generated from a Monte Carlo program based on the formulas presented in this paper. All the results of this paper are also applicable to the semileptonic and nonleptonic decays of ground state charm and bottom baryons, and to the decays of the top quark.Comment: Published version. 40 pages, 11 figures included in the text. Typos corrected, comments added, references added and update

    Observation of the Ankle and Evidence for a High-Energy Break in the Cosmic Ray Spectrum

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    We have measured the cosmic ray spectrum at energies above 101710^{17} eV using the two air fluorescence detectors of the High Resolution Fly's Eye experiment operating in monocular mode. We describe the detector, PMT and atmospheric calibrations, and the analysis techniques for the two detectors. We fit the spectrum to models describing galactic and extragalactic sources. Our measured spectrum gives an observation of a feature known as the ``ankle'' near 3×10183\times 10^{18} eV, and strong evidence for a suppression near 6×10196\times 10^{19} eV.Comment: 14 pages, 9 figures. To appear in Physics Letters B. Accepted versio
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