2,022 research outputs found

    B Physics on the Lattice: Λ‟\overline{\Lambda}, λ1\lambda_{1}, m‟b(m‟b)\overline{m}_{b}(\overline{m}_{b}), λ2\lambda_2, B0−Bˉ0B^{0}-\bar{B}^{0} mixing, \fb and all that

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    We present a short review of our most recent high statistics lattice determinations in the HQET of the following important parameters in B physics: the B--meson binding energy, Λ‟\overline{\Lambda} and the kinetic energy of the b quark in the B meson, λ1\lambda_1, which due to the presence of power divergences require a non--perturbative renormalization to be defined; the MS‟\overline{MS} running mass of the b quark, m‟b(m‟b)\overline{m}_{b}(\overline{m}_{b}); the B∗B^{*}--BB mass splitting, whose value in the HQET is determined by the matrix element of the chromo--magnetic operator between B meson states, λ2\lambda_2; the B parameter of the B0B^{0}--Bˉ0\bar{B}^{0} mixing, BBB_{B}, and the decay constant of the B meson, fBf_{B}. All these quantities have been computed using a sample of 600600 gauge field configurations on a 243×4024^{3}\times 40 lattice at ÎČ=6.0\beta=6.0. For Λ‟\overline{\Lambda} and m‟b(m‟b)\overline{m}_{b}(\overline{m}_{b}), we obtain our estimates by combining results from three independent lattice simulations at ÎČ=6.0\beta=6.0, 6.26.2 and 6.46.4 on the same volume.Comment: 3 latex pages, uses espcrc2.sty (included). Talk presented at LATTICE96(heavy quarks

    Analysis of intermittency in submillimeter radio and hard x-ray data during the impulsive phase of a solar flare

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    We present an analysis of intermittent processes occurring during the impulsive phase of the flare SOL2012-03-13, using hard X-rays and submillimeter radio data. Intermittency is a key characteristic in turbulent plasmas and has so far only been analyzed for hard X-ray data. Since in a typical flare the same accelerated electron population is believed to produce both hard X-rays and gyrosynchrotron radiation, we compare the two time profiles by searching for intermittency signatures. For this, we define a cross-wavelet power spectrum, which is used to obtain the local intermittency measure, or LIMLIM. When greater than three, the square LIMLIM coefficients indicate a local intermittent process. The LIM2LIM2 coefficient distribution in time and scale helps to identify avalanche or cascade energy release processes. We find two different and well-separated intermittent behaviors in the submillimeter data: for scales greater than 20 s, a broad distribution during the rising and maximum phases of the emission seems to favor a cascade process; for scales below 1 s, short pulses centered on the peak time are representative of avalanches. When applying the same analysis to hard X-rays, we find that only the scales above 10 s produce a distribution related to a cascade energy fragmentation. Our results suggest that different acceleration mechanisms are responsible for tens of keV and MeV energy ranges of electrons

    HeteroGenius: A Framework for Hybrid Analysis of Heterogeneous Software Specifications

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    Nowadays, software artifacts are ubiquitous in our lives being an essential part of home appliances, cars, cell phones, and even in more critical activities like aeronautics and health sciences. In this context software failures may produce enormous losses, either economical or, in the worst case, in human lives. Software analysis is an area in software engineering concerned with the application of diverse techniques in order to prove the absence of errors in software pieces. In many cases different analysis techniques are applied by following specific methodological combinations that ensure better results. These interactions between tools are usually carried out at the user level and it is not supported by the tools. In this work we present HeteroGenius, a framework conceived to develop tools that allow users to perform hybrid analysis of heterogeneous software specifications. HeteroGenius was designed prioritising the possibility of adding new specification languages and analysis tools and enabling a synergic relation of the techniques under a graphical interface satisfying several well-known usability enhancement criteria. As a case-study we implemented the functionality of Dynamite on top of HeteroGenius.Comment: In Proceedings LAFM 2013, arXiv:1401.056

    B−BˉB - \bar B Mixing in the HQET

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    We present a high statistics, quenched lattice calculation of the B-parameters BBdB_{B_d} and BBsB_{B_s}, computed at lowest order in the HQET. The results were obtained using a sample of 600 quenched gauge field configurations, generated by Monte Carlo simulation at ÎČ=6.0\beta=6.0 on a 243×4024^{3}\times 40 lattice. For the light quarks the SW-Clover action was used; the propagator of the lattice HQET was also tree-level improved. Our best estimate of the renormalization scale independent B-parameter is B^Bd=1.03±0.06±0.18\hat{B}_{B_d} = 1.03 \pm 0.06 \pm 0.18. B^Bd\hat{B}_{B_d} has been obtained by using ``boosted'' perturbation theory to calculate the renormalization constants which relate the matrix elements of the lattice operators to the corresponding amplitudes in the continuum. Due to the large statistics, the errors in the extraction of the matrix elements of the relevant bare operators are rather small. The main systematic error, corresponding to ±0.18\pm 0.18 in the above result, comes from the uncertainty in the evaluation of the renormalization constants, for which the one-loop corrections are rather large. The non-perturbative evaluation of these constants will help to reduce the final error. We also obtain B^Bs/B^Bd=1.01±0.01\hat{B}_{B_s}/\hat{B}_{B_d} = 1.01 \pm 0.01 and fBs2B^Bs/fBd2B^Bd=1.38±0.07f^2_{B_s}\hat{B}_{B_s}/f^2_{B_d}\hat{B}_{B_d} = 1.38 \pm 0.07.Comment: 15 pages, Latex, 2 figures, Small numerical errors corrected, no conclusions change

    Egg quality variability in common dentex (Dentex dentex, L.): Comparison of different quality indexes

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    The egg quality of two common dentex captive broodstocks were monitored for two consecutive years during their natural spawning season. Volume of spawned eggs, volume of buoyant eggs, fertilization rate, egg weight, hatching rate and mortality of larvae were recorded. According to the volume of spawned eggs, the ratio of buoyant eggs spawned, the number of spawning days and the fertilization rate pointed to an improvement from Year 1 to Year 2. But data on hatching rate and larval mortality lead to the opposite conclusion.info:eu-repo/semantics/acceptedVersio

    A High Statistics Lattice Calculation of The B-meson Binding Energy

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    We present a high statistics lattice calculation of the B--meson binding energy Λ‟\overline{\Lambda} of the heavy--quark inside the pseudoscalar B--meson. Our numerical results have been obtained from several independent numerical simulations at ÎČ=6.0\beta=6.0, 6.26.2 and 6.46.4, and using, for the meson correlators, the results obtained by the APE group at the same values of ÎČ\beta. Our best estimate, obtained by combining results at different values of ÎČ\beta, is Λ‟=180−20+30\overline{\Lambda}=180^{+30}_{-20} MeV. For the MS‟\overline{MS} running mass, we obtain m‟b(m‟b)=4.15±0.05±0.20\overline{m}_{b}(\overline{m}_{b})=4.15 \pm 0.05 \pm 0.20 GeV, in reasonable agreement with previous determinations. The systematic error is the truncation of the perturbative series in the matching condition of the relevant operator of the Heavy Quark Effective Theory.Comment: Latex, 13 pages, 1 figure appended in uuencoded gzip.tar.fil

    A burst with double radio spectrum observed up to 212 GHz

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    We study a solar flare that occurred on September 10, 2002, in active region NOAA 10105 starting around 14:52 UT and lasting approximately 5 minutes in the radio range. The event was classified as M2.9 in X-rays and 1N in H\alpha. Solar Submillimeter Telescope observations, in addition to microwave data give us a good spectral coverage between 1.415 and 212 GHz. We combine these data with ultraviolet images, hard and soft X-rays observations and full-disk magnetograms. Images obtained from Ramaty High Energy Solar Spectroscopic Imaging data are used to identify the locations of X-ray sources at different energies and to determine the X-ray spectrum, while ultra violet images allow us to characterize the coronal flaring region. The magnetic field evolution of the active region is analyzed using Michelson Doppler Imager magnetograms. The burst is detected at all available radio-frequencies. X-ray images (between 12 keV and 300 keV) reveal two compact sources and 212 GHz data, used to estimate the radio source position, show a single compact source displaced by 25" from one of the hard X-ray footpoints. We model the radio spectra using two homogeneous sources, and combine this analysis with that of hard X-rays to understand the dynamics of the particles. Relativistic particles, observed at radio wavelengths above 50 GHz, have an electron index evolving with the typical soft-hard-soft behaviour.Comment: Submitted to Solar Physics, 20 pages, 8 fugure

    Matrix Elements without Quark Masses on the Lattice

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    We introduce a new parameterization of four-fermion matrix elements which does not involve quark masses and thus allows a reduction of systematic uncertainties in physical amplitudes. As a result the apparent quadratic dependence of e'/e on m_s is removed. To simplify the matching between lattice and continuum renormalization schemes, we express our results in terms of Renormalization Group Invariant B-parameters which are renormalization-scheme and scale independent. As an application of our proposal, matrix elements of DeltaI=3/2 and SUSY DeltaF=2 (F=S,C,BF=S,C,B) four-fermion operators have been computed.Comment: LATTICE99(Matrix Elements), 3 pages, 1 figure, BUHEP-99-2

    Orbital phase resolved spectroscopy of 4U1538-52 with MAXI

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    4U 1538-52, an absorbed high mass X-ray binary with an orbital period of 3.73 days, shows moderate orbital intensity modulations with a low level of counts during the eclipse. Several models have been proposed to explain the accretion at different orbital phases by a spherically symmetric stellar wind from the companion. The aim of this work is to study both the light curve and orbital phase spectroscopy of this source in the long term. Particularly, the folded light curve and the changes of the spectral parameters with orbital phase to analyse the stellar wind of QV Nor, the mass donor of this binary system. We used all the observations made from the Gas Slit Camera on board MAXI of 4U 1538-52 covering many orbits continuously. We obtained the good interval times for every orbital phase range which were the input to extract our data. We estimated the orbital period of the system and then folded the light curves and we fitted the X-ray spectra with the same model for every orbital phase spectrum. We also extracted the averaged spectrum of all the MAXI data available. The MAXI spectra in the 2-20 keV energy range were fitted with an absorbed Comptonization of cool photons on hot electrons. We found a strong orbital dependence of the absorption column density but neither the fluorescence iron emission line nor low energy excess were needed to fit the MAXI spectra. The variation of the spectral parameters over the binary orbit were used to examine the mode of accretion onto the neutron star in 4U 1538-52. We deduce a best value of M˙/v∞=0.65×10−9\dot{M}/v_\infty=0.65\times 10^{-9} M⊙ yr−1/(km s−1)M_{\odot} \, yr^{-1}/(km \, s^{-1}) for QV Nor.Comment: 12 pages, 5 figures, accepted to be published by A&A, corrected typos (changing bold font to normal one
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