1,018 research outputs found

    How BMW Is Defusing the Demographic Time Bomb

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    The article focuses on how the German car manufacturer, Bayerische Motoren Werke AG or BMW, is managing the effects of population aging on the industry. The redesign of BMW's factories to accommodate older workers and increase productivity is mentioned. Research on a pilot production line, which is based on a mix of employees who have an average age of 47 in the year 2017, is discussed. The roles of Peter Jürschick, Helmut Mauermann, Günther Stadler, and Kurt Dickert in the development of the pilot project are mentioned. The costs associated with an aging population are noted

    Study of Bc --> J/psi pi, etac pi decays with perturbative QCD approach

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    The Bc --> J/psi pi, etac pi decays are studied with the perturbative QCD approach. It is found that form factors and branching ratios are sensitive to the parameters w, v, f_J/psi and f_etac, where w and v are the parameters of the charmonium wave functions for Coulomb potential and harmonic oscillator potential, respectively, f_J/psi and f_etac are the decay constants of the J/psi and etac mesons, respectively. The large branching ratios and the clear signals of the final states make the Bc --> J/psi pi, etac pi decays to be the prospective channels for measurements at the hadron collidersComment: 21 pages, revtex

    Nonfactorizable contributions to BD()MB \to D^{(*)} M decays

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    While the factorization assumption works well for many two-body nonleptonic BB meson decay modes, the recent measurement of BˉD()0M0\bar B\to D^{(*)0}M^0 with M=πM=\pi, ρ\rho and ω\omega shows large deviation from this assumption. We analyze the BD()MB\to D^{(*)}M decays in the perturbative QCD approach based on kTk_T factorization theorem, in which both factorizable and nonfactorizable contributions can be calculated in the same framework. Our predictions for the Bauer-Stech-Wirbel parameters, a2/a1=0.43±0.04|a_2/a_1|= 0.43\pm 0.04 and Arg(a2/a1)42Arg(a_2/a_1)\sim -42^\circ and a2/a1=0.47±0.05|a_2/a_1|= 0.47\pm 0.05 and Arg(a2/a1)41Arg(a_2/a_1)\sim -41^\circ, are consistent with the observed BDπB\to D\pi and BDπB\to D^*\pi branching ratios, respectively. It is found that the large magnitude a2|a_2| and the large relative phase between a2a_2 and a1a_1 come from color-suppressed nonfactorizable amplitudes. Our predictions for the Bˉ0D()0ρ0{\bar B}^0\to D^{(*)0}\rho^0, D()0ωD^{(*)0}\omega branching ratios can be confronted with future experimental data.Comment: 25 pages with Latex, axodraw.sty, 6 figures and 5 tables, Version published in PRD, Added new section 5 and reference

    Nonlinear spin wave excitations at low magnetic bias fields

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    Nonlinear magnetization dynamics is essential for the operation of numerous spintronic devices ranging from magnetic memory to spin torque microwave generators. Examples are microwave assisted switching of magnetic structures and the generation of spin currents at low bias fields by high amplitude ferromagnetic resonance. Here we use X ray magnetic circular dichroism to determine the number density of excited magnons in magnetically soft Ni80Fe20 thin films. Our data show that the common model of nonlinear ferromagnetic resonance is not adequate for the description of the nonlinear behaviour in the low magnetic field limit. Here we derive a model of parametric spin wave excitation, which correctly predicts nonlinear threshold amplitudes and decay rates at high and at low magnetic bias fields. In fact, a series of critical spin wave modes with fast oscillations of the amplitude and phase is found, generalizing the theory of parametric spin wave excitation to large modulation amplitude

    Final state interaction and BKKB\to KK decays in perturbative QCD

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    We predict branching ratios and CP asymmetries of the BKKB\to KK decays using perturbative QCD factorization theorem, in which tree, penguin, and annihilation contributions, including both factorizable and nonfactorizable ones, are expressed as convolutions of hard six-quark amplitudes with universal meson wave functions. The unitarity angle ϕ3=90o\phi_3= 90^o and the BB and KK meson wave functions extracted from experimental data of the BKπB\to K\pi and ππ\pi\pi decays are employed. Since the BKKB\to KK decays are sensitive to final-state-interaction effects, the comparision of our predictions with future data can test the neglect of these effects in the above formalism. The CP asymmetry in the B±K±K0B^\pm\to K^\pm K^0 modes and the Bd0K±KB_d^0\to K^\pm K^\mp branching ratios depend on annihilation and nonfactorizable amplitudes. The BKKB\to KK data can also verify the evaluation of these contributions.Comment: 13 pages in latex file, 7 figures in ps file

    Applicability of perturbative QCD to ΛbΛc\Lambda_b \to \Lambda_c decays

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    We develop perturbative QCD factorization theorem for the semileptonic heavy baryon decay ΛbΛclνˉ\Lambda_b \to \Lambda_c l\bar{\nu}, whose form factors are expressed as the convolutions of hard bb quark decay amplitudes with universal Λb\Lambda_b and Λc\Lambda_c baryon wave functions. Large logarithmic corrections are organized to all orders by the Sudakov resummation, which renders perturbative expansions more reliable. It is observed that perturbative QCD is applicable to ΛbΛc\Lambda_b \to \Lambda_c decays for velocity transfer greater than 1.2. Under requirement of heavy quark symmetry, we predict the branching ratio B(ΛbΛclνˉ)2B(\Lambda_b \to \Lambda_c l{\bar\nu})\sim 2%, and determine the Λb\Lambda_b and Λc\Lambda_c baryon wave functions.Comment: 12 pages in Latex file, 3 figures in postscript files, some results are changed, but the conclusion is the sam

    Final-state interaction and s-quark helicity conservation in B -> J/psi K*

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    The Section of charm quark spin conservation is deleted since it involves more dynamical assumptions than previously stated. A few comments are added in view of new experimental results.Comment: To replace the earlier version of hep-ph/0106354. Minor additions and one deletion with no change in the main argument nor the conclusio

    Rare Decays of \Lambda_b->\Lambda + \gamma and \Lambda_b ->\Lambda + l^{+} l^{-} in the Light-cone Sum Rules

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    Within the Standard Model, we investigate the weak decays of ΛbΛ+γ\Lambda_b \to \Lambda + \gamma and ΛbΛ+l+l\Lambda_b \to \Lambda + l^{+} l^{-} with the light-cone sum rules approach. The higher twist distribution amplitudes of Λ\Lambda baryon to the leading conformal spin are included in the sum rules for transition form factors. Our results indicate that the higher twist distribution amplitudes almost have no influences on the transition form factors retaining the heavy quark spin symmetry, while such corrections can result in significant impacts on the form factors breaking the heavy quark spin symmetry. Two phenomenological models (COZ and FZOZ) for the wave function of Λ\Lambda baryon are also employed in the sum rules for a comparison, which can give rise to the form factors approximately 5 times larger than that in terms of conformal expansion. Utilizing the form factors calculated in LCSR, we then perform a careful study on the decay rate, polarization asymmetry and forward-backward asymmetry, with respect to the decays of ΛbΛγ\Lambda_b \to \Lambda \gamma, Λl+l\Lambda l^{+}l^{-}.Comment: 38 pages, 15 figures, some typos are corrected and more references are adde

    Final state interactions in the decay B0ηcKB^0 \to \eta_c K^*

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    In this article, we study the final-state rescattering effects in the decay B0ηcKB^0 \to \eta_cK^*, the numerical results indicate the corrections are comparable with the contribution from the naive factorizable amplitude, and the total amplitudes can accommodate the experimental data.Comment: 11 pages, 1 figure, revised version, to appear in EPJ

    Phenomenological Analysis of B->PP Decays with QCD Factorization

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    In this paper, we study nonleptonic charmless B decays to two light pseudoscalar mesons within the frame of QCD factorization, including the contributions from the chirally enhanced power corrections and weak annihilation. Predictions for the CP-averaged branching ratios and CP-violating asymmetries are given. Within the reasonable range of the parameters, we find that our predictions for the branching ratios of B -> PP are consistent with the present experimental data. But because of the logarithmic divergences at the endpoints in the hard spectator scatterings and weak annihilation, there are still large uncertainties in these predictions.Comment: 34 pages, 5 figures. to appear in PR
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