56,255 research outputs found

    Determinations of |V_ub| and |V_cb| from measurements of B -> X_u,c\ell\nu differential decay rates

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    Methods are described in the framework of light-cone expansion which allow one to determine the Cabibbo-Kobayashi-Maskawa matrix elements |V_ub| and |V_cb| from measurements of the differential decay rates as a function of the scaling variables in the inclusive semileptonic decays of B mesons. By these model-independent methods the dominant hadronic uncertainties can be avoided and the B -> X_u\ell\nu decay can be very efficiently differentiated from the B -> X_c\ell\nu decay, which may lead to precise determinations of |V_ub| and |V_cb|.Comment: 11 pages, 2 figures, version as published in Mod. Phys. Lett. A, more discussion, references added, title chang

    Dynamics underlying Box-office: Movie Competition on Recommender Systems

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    We introduce a simple model to study movie competition in the recommender systems. Movies of heterogeneous quality compete against each other through viewers' reviews and generate interesting dynamics of box-office. By assuming mean-field interactions between the competing movies, we show that run-away effect of popularity spreading is triggered by defeating the average review score, leading to hits in box-office. The average review score thus characterizes the critical movie quality necessary for transition from box-office bombs to blockbusters. The major factors affecting the critical review score are examined. By iterating the mean-field dynamical equations, we obtain qualitative agreements with simulations and real systems in the dynamical forms of box-office, revealing the significant role of competition in understanding box-office dynamics.Comment: 8 pages, 6 figure

    Make and learn: A CS Principles course based on the Arduino platform

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    We present preliminary experiences in designing a Computer Science Principles undergraduate course for all majors that is based on physical computing with the Arduino microprocessor platform. The course goal is to introduce students to fundamental computing concepts in the context of developing concrete products. This physical computing approach is different from other existing CS Principles courses. Students use the Arduino platform to design tangible interactive systems that are personally and socially relevant to them, while learning computing concepts and reflecting on their experiences. In a previous publication [1], we reported on assessment results of using the Arduino platform in an Introduction to Digital Design course. We have introduced this platform in an introductory computing course at the University of Hartford in the past year as well as in a Systems Fundamentals Discovery Course at the University of New Hampshire to satisfy the general education requirements in the Environment, Technology, and Society category. Our goal is to align the current curriculum with the CS Principles framework to design a course that engages a broader audience through a creative making and contextualized learning experience

    Analysis of hadronic invariant mass spectrum in inclusive charmless semileptonic B decays

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    We make an analysis of the hadronic invariant mass spectrum in inclusive charmless semileptonic B meson decays in a QCD-based approach. The decay width is studied as a function of the invariant mass cut. We examine their sensitivities to the parameters of the theory. The theoretical uncertainties in the determination of Vub|V_{ub}| from the hadronic invariant mass spectrum are investigated. A strategy for improving the theoretical accuracy in the value of Vub|V_{ub}| is described.Comment: 13 pages, 5 Postscript figure

    Semi-Inclusive B\to K(K^*) X Decays with Initial Bound State Effects

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    The effects of initial bb quark bound state for the semi-inclusive decays BK(K)XB\to K(K^*) X are studied using light cone expansion and heavy quark effective theory methods. We find that the initial bound state effects on the branching ratios and CP asymmetries are small. In the light cone expansion approach, the CP-averaged branching ratios are increased by about 2% with respect to the free bb-quark decay. For Bˉ0K(K)X\bar B^0 \to K^- (K^{*-}) X, the CP-averaged branching ratios are sensitive to the phase γ\gamma and the CP asymmetry can be as large as 7% (14%), whereas for BKˉ0(Kˉ0)XB^-\to \bar K^0 (\bar K^{*0})X the CP-averaged branching ratios are not sensitive to γ\gamma and the CP asymmetries are small (<1< 1%). The CP-averaged branching ratios are predicted to be in the ranges (0.531.5)×104(0.53 \sim 1.5)\times 10^{-4} [(0.252.0)×104(0.25 \sim 2.0)\times 10^{-4}] for Bˉ0K(K)X\bar B^0 \to K^- (K^{*-})X and (0.770.84)×104(0.77 \sim 0.84)\times 10^{-4} [(0.670.74)×104(0.67 \sim 0.74)\times 10^{-4}] for BKˉ0(Kˉ0)XB^-\to \bar K^0 (\bar K^{*0}) X, depending on the value of the CP violating phase γ\gamma. In the heavy quark effective theory approach, we find that the branching ratios are decreased by about 10% and the CP asymmetries are not affected. These predictions can be tested in the near future.Comment: 29 pages, 12 ps figure