234,607 research outputs found

    The Effects of the Massless O(alpha_s^2), O(\alpha\alpha_s), O(\alpha^2) QCD and QED Corrections and of the Massive Contributions to Gamma(H^0\rightarrow b\overline{b})

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    We consider in detail various theoretical uncertainties of the perturbative predictions for the decay width of H0→bb‾H^0\rightarrow b\overline{b} process in the region 50 GeV<MH≤2MW50\ GeV< M_H\leq 2M_W. We calculate the order O(αs2)O(\alpha_s^2)-contributions to the expression for ΓHbb‾\Gamma_{Hb\overline{b}} through the pole quark mass and demonstrate that they are important for the elimination of the numerical difference between the corresponding expression and the one through the running bb-quark mass. The order O(ααs)O(\alpha\alpha_s) and O(α2)O(\alpha^2) massless and order O(mb2/MH2)O(m_b^2/M_H^2) massive corrections to ΓHbb‾\Gamma_{Hb\overline{b}} are also calculated. The importance of the latter contributions for modeling of the threshold effects is demonstrated. The troubles with identifying of the 4 recent L3 events e+e−→l+l−γγe^+e^-\rightarrow l^+l^-\gamma\gamma with the decay of a Standard Higgs boson are discussed.Comment: 16 pages, 6 figures (can be optained by mail after the request from the authers, e-mails: [email protected]; [email protected]); LATEX, modified version of ENSLAPP.-A.-407/92 preprin

    Grappling with Issues of Learning Science from Everyday Experiences: An Illustrative Case Study

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    There are different perceptions among researchers with regard to the infusion of everyday experience in the teaching of science: 1) it hinders the learning of science concepts; or, 2) it increases the participation and motivation of students in science learning. This article attempts to contemplate those different perspectives of everyday knowledge in science classrooms by using everyday contexts to teach grade 3 science in Singapore. In this study, two groups of grade 3 students were presented with a scenario that required them to apply the concept of properties of materials to design a shoe. Subsequently, the transcripts of classroom discussions and interactions were analyzed using the framework of sociocultural learning and an interpretative analytic lens. Our analysis suggests that providing an authentic everyday context is insufficient to move young learners of science from their everyday knowledge to scientific knowledge. Further, group interactions among young learners of science to solve an everyday issue need to be scaffolded to ensure meaningful, focused, and sustained learning. Implications for research in science learning among younger students are discussed

    Nanowire formation on sputter eroded surfaces

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    Rotated ripple structures (RRS) on sputter eroded surfaces are potential candidates for nanoscale wire fabrication. We show that the necessary condition for RRS formation is that the width of the collision cascade in the longitudinal direction has to be larger than that in the transverse direction, which can be achieved by using high energy ion beams. By calculating the structure factor for the RRS we find that they are more regular and their amplitude is more enhanced compared to the much studied ripple structure forming in the linear regime of sputter erosion.Comment: 3 pages, 5 figures, 2 column revtex format, submitted to Appl. Phys. Let

    On Types of Elliptic Pseudoprimes

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    We generalize the notions of elliptic pseudoprimes and elliptic Carmichael numbers introduced by Silverman to analogues of Euler-Jacobi and strong pseudoprimes. We investigate the relationships among Euler Elliptic Carmichael numbers , strong elliptic Carmichael numbers, products of anomalous primes and elliptic Korselt numbers of Type I: The former two of these are introduced in this paper, and the latter two of these were introduced by Mazur (1973) and Silverman (2012) respectively. In particular, we expand upon a previous work of Babinkostova et al. by proving a conjecture about the density of certain elliptic Korselt numbers of Type I that are products of anomalous primes.Comment: Revised for publication. 33 page

    Multivariate p-dic L-function

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    We construct multivariate p-adic L-function in the p-adic number fild by using Washington method.Comment: 9 page

    A Package for the Automated Classification of Periodic Variable Stars

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    We present a machine learning package for the classification of periodic variable stars. Our package is intended to be general: it can classify any single band optical light curve comprising at least a few tens of observations covering durations from weeks to years, with arbitrary time sampling. We use light curves of periodic variable stars taken from OGLE and EROS-2 to train the model. To make our classifier relatively survey-independent, it is trained on 16 features extracted from the light curves (e.g. period, skewness, Fourier amplitude ratio). The model classifies light curves into one of seven superclasses - Delta Scuti, RR Lyrae, Cepheid, Type II Cepheid, eclipsing binary, long-period variable, non-variable - as well as subclasses of these, such as ab, c, d, and e types for RR Lyraes. When trained to give only superclasses, our model achieves 0.98 for both recall and precision as measured on an independent validation dataset (on a scale of 0 to 1). When trained to give subclasses, it achieves 0.81 for both recall and precision. In order to assess classification performance of the subclass model, we applied it to the MACHO, LINEAR, and ASAS periodic variables, which gave recall/precision of 0.92/0.98, 0.89/0.96, and 0.84/0.88, respectively. We also applied the subclass model to Hipparcos periodic variable stars of many other variability types that do not exist in our training set, in order to examine how much those types degrade the classification performance of our target classes. In addition, we investigate how the performance varies with the number of data points and duration of observations. We find that recall and precision do not vary significantly if the number of data points is larger than 80 and the duration is more than a few weeks. The classifier software of the subclass model is available from the GitHub repository (https://goo.gl/xmFO6Q).Comment: 16 pages, 11 figures, accepted for publication in A&

    Off-diagonal magnetoimpedance in field-annealed Co-based amorphous ribbons

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    The off-diagonal magnetoimpedance in field-annealed CoFeSiB amorphous ribbons was measured in the low-frequency range using a pick-up coil wound around the sample. The asymmetric two-peak behavior of the field dependence of the off-diagonal impedance was observed. The asymmetry is attributed to the formation of a hard magnetic crystalline phase at the ribbon surface. The experimental results are interpreted in terms of the surface impedance tensor. It is assumed that the ribbon consists of an inner amorphous region and surface crystalline layers. The coupling between the crystalline and amorphous phases is described through an effective bias field. A qualitative agreement between the calculated dependences and experimental data is demonstrated. The results obtained may be useful for development of weak magnetic-field sensors.Comment: 19 pages, 6 figure
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