4,627 research outputs found

    Charmless B(s)→VVB_{(s)}\to VV Decays in Factorization-Assisted Topological-Amplitude Approach

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    Within the factorization-assisted topological-amplitude approach, we studied the 33 charmless B(s)→VVB_{(s)} \to VV decays, where VV stands for a light vector meson. According to the flavor flows, the amplitude of each process can be decomposed into 8 different topologies. In contrast to the conventional flavor diagrammatic approach, we further factorize each topological amplitude into decay constant, form factors and unknown universal parameters. By χ2\chi^2 fitting 46 experimental observables, we extracted 10 theoretical parameters with χ2\chi^2 per degree of freedom around 2. Using the fitted parameters, we calculated the branching fractions, polarization fractions, CP asymmetries and relative phases between polarization amplitudes of each decay mode. The decay channels dominated by tree diagram have large branching fractions and large longitudinal polarization fraction. The branching fractions and longitudinal polarization fractions of color-suppressed decays become smaller. Current experimental data of large transverse polarization fractions in the penguin dominant decay channels can be explained by only one transverse amplitude of penguin annihilation diagram. Our predictions of those not yet measured channels can be tested in the ongoing LHCb experiment and the Belle-II experiment in future.Comment: 22 pages, 2 figure

    Observations on shifted cumulative regulation

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    A response to Dynamic cumulative activity of transcription factors as a mechanism of quantitative gene regulation by F He, J Buer, AP Zeng and R Balling. Genome Biol 2007, 8:R181

    An Advanced Control and Extensible Configuration for Static Var Generator

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    An extensible configuration is proposed for static var generator (SVG) with advanced controller included for reactive power compensation of grid. Compared with the traditional configurations, the major advantage of such system configuration is that the power modules are very flexible and easy to extend or reduce without changing the main equipment of SVG under the different voltage levels. Furthermore, in order to solve the problems of modeling uncertainty, nonlinearities, and outside disturbance by using proportion integration (PI) controller, an advanced controller is proposed based on auto disturbance rejection control (ADRC). By controlling the amount and direction of reactive current, the reactive power is generated or absorbed from SVG into power grid with fast response, which can realize the excellent dynamic compensation for both the internal and external interferences. Simulations results show that the proposed controller has better performance of the transient and steady state than PI controller. Moreover, the verification tests are executed in 380 V, 6.5 kVA experiment systems, suggesting that the excellent dynamic performance and strong robustness are achieved

    Examining Scientific Writing Styles from the Perspective of Linguistic Complexity

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    Publishing articles in high-impact English journals is difficult for scholars around the world, especially for non-native English-speaking scholars (NNESs), most of whom struggle with proficiency in English. In order to uncover the differences in English scientific writing between native English-speaking scholars (NESs) and NNESs, we collected a large-scale data set containing more than 150,000 full-text articles published in PLoS between 2006 and 2015. We divided these articles into three groups according to the ethnic backgrounds of the first and corresponding authors, obtained by Ethnea, and examined the scientific writing styles in English from a two-fold perspective of linguistic complexity: (1) syntactic complexity, including measurements of sentence length and sentence complexity; and (2) lexical complexity, including measurements of lexical diversity, lexical density, and lexical sophistication. The observations suggest marginal differences between groups in syntactical and lexical complexity.Comment: 6 figure

    Types of Scientific Collaborators: A Perspective of Author Contribution Network

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    The purpose of this study is to investigate interaction between collaborators within individual studies by measuring how they made contributions to their studies. Author contribution network is constructed based on the author contribution statements of 140,000 full-text articles in PloS by viewing every collaborator as a node and a shared contribution as an edge. Three types of contributors are identified: general team-players, factotums, and mavericks. The preliminary result suggests that division of labor widely exists in scientific re-search and the latter two types of collaborators are common in small teams

    Υ\Upsilon radiative decays to light quark jets and color octet mechanism

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    We study radiative decays of Υ\Upsilon to light quark jets in nonrelativistic QCD by taking both the color singlet and color octet bbˉb\bar b operators into consideration. The cut for quark jet energy and cut for the angle between two quark jets are introduced. The sensitivity to the soft and collinear singularities in the loop integrals are greatly reduced by these cuts. With the jet energy cut of about 1 GeV, and the jet angle cut of about 36∘36^\circ, the branching ratio for Υ→γqqˉ\Upsilon\to\gamma q\bar q is found to be 8.2×10−48.2\times 10^{-4} from color singlet contributions. The color octet contributions could be much larger than that of color singlet, depending on the estimate of the color octet matrix elements. This process may provide a new test for the color octet mechanism in nonrelativistic QCD.Comment: journal version; a few references adde
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