5,028 research outputs found

    A Comparative Study of the Decays B(K,K)+B \to (K,K^*) \ell^+ \ell^- in Standard Model and Supersymmetric Theories

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    Using improved theoretical calculations of the decay form factors in the Light Cone-QCD sum rule approach, we investigate the decay rates, dilepton invariant mass spectra and the forward-backward (FB) asymmetry in the decays B(K,K)+B \to (K,K^*) \ell^+ \ell^- (±=e±,μ±,τ±\ell^\pm =e^\pm,\mu^\pm,\tau^\pm) in the standard model (SM) and a number of popular variants of the supersymmetric (SUSY) models. Theoretical precision on the differential decay rates and FB-asymmetry is estimated in these theories taking into account various parametric uncertainties. We show that existing data on BXsγB \to X_s \gamma and the experimental upper limit on the branching ratio B(BKμ+μ){\cal B}(B \to K^* \mu^+ \mu^-) provide interesting bounds on the coefficients of the underlying effective theory. We argue that the FB-asymmetry in BK+B \to K^* \ell^+ \ell^- constitutes a precision test of the SM and its measurement in forthcoming experiments may reveal new physics. In particular, the presently allowed large-tanβ\tan \beta solutions in SUGRA models, as well as more general flavor-violating SUSY models, yield FB-asymmetries which are characteristically different from the corresponding ones in the SM.Comment: 36 pages, 12 figures (require epsfig.sty), 8 Tables, LaTeX2e; subsection 6.4 corrected, minor changes in numerical results, Figures 3 and 9 to 12 modified; submitted to Physical Review

    Surfing, self-medicating and safety: buying non-prescription and complementary medicines via the internet

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    © 2003 BMJ Publishing Group & Institute for Healthcare ImprovementObjective: To examine whether the sale of medicines via the internet supports their safe and appropriate use. Design: e-Pharmacy websites were identified using key words and a metasearch engine and the quality of information published on these websites was surveyed using the DISCERN tool. A case scenario and internet pharmacy practice standards were also used to evaluate the quality of care delivered. Setting and participants: Between July and September 2001 104 websites were surveyed and 27 sent either Sudafed (pseudoephedrine HCl), St John’s wort products, or both to a residential address in Melbourne, Australia. Main outcome measures: Quality of health information (DISCERN ratings), information exchanged between e-pharmacy staff and consumers, and product and delivery costs. Results: Of 104 e-pharmacies from at least 13 different countries, 63 websites provided some health information but overall the quality of the information was poor. Only three website operators provided adequate advice to consumers to avoid a potential drug interaction. The costs for a daily dose of pseudoephedrine HCl (240 mg) ranged from A0.81toA0.81 to A3.04, and delivery costs from A3.28toA3.28 to A62.70. Conclusion: Consumers who self-select medicines from websites have insufficient access to information and advice at the point of ordering and on delivery to make informed decisions about their safe and appropriate use.T L Bessell, J N Anderson, C A Silagy, L N Sansom and J E Hille

    Strong Lefschetz elements of the coinvariant rings of finite Coxeter groups

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    For the coinvariant rings of finite Coxeter groups of types other than H4_4, we show that a homogeneous element of degree one is a strong Lefschetz element if and only if it is not fixed by any reflections. We also give the necessary and sufficient condition for strong Lefschetz elements in the invariant subrings of the coinvariant rings of Weyl groups.Comment: 18 page

    Counting statistics in multiple path geometries and the fluctuations of the integrated current in a quantum stirring device

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    The amount QQ of particles that are transported via a path of motion is characterized by its expectation value and by its variance Var(Q)Var(Q). We analyze what happens if a particle has two optional paths available to get from one site to another site, and in particular what is Var(Q)Var(Q) for the current which is induced in a quantum stirring device. It turns out that coherent splitting and the stirring effect are intimately related and cannot be understood within the framework of the prevailing probabilistic theory.Comment: 11 pages, 2 figures, published version, Latex Eq# correcte

    Control of atomic currents using a quantum stirring device

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    We propose a BEC stirring device which can be regarded as the incorporation of a quantum pump into a closed circuit: it produces a DC circulating current in response to a cyclic adiabatic change of two control parameters of an optical trap. We demonstrate the feasibility of this concept and point out that such device can be utilized in order to probe the interatomic interactions.Comment: 5 pages, 4 figures, uses epl2.cls, revised versio

    Microscopic features of moving traffic jams

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    Empirical and numerical microscopic features of moving traffic jams are presented. Based on a single vehicle data analysis, it is found that within wide moving jams, i.e., between the upstream and downstream jam fronts there is a complex microscopic spatiotemporal structure. This jam structure consists of alternations of regions in which traffic flow is interrupted and flow states of low speeds associated with "moving blanks" within the jam. Empirical features of the moving blanks are found. Based on microscopic models in the context of three-phase traffic theory, physical reasons for moving blanks emergence within wide moving jams are disclosed. Structure of moving jam fronts is studied based in microscopic traffic simulations. Non-linear effects associated with moving jam propagation are numerically investigated and compared with empirical results.Comment: 19 pages, 12 figure

    Ultraviolet and Infrared Divergences in Implicit Regularization: a Consistent Approach

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    Implicit Regularization is a 4-dimensional regularization initially conceived to treat ultraviolet divergences. It has been successfully tested in several instances in the literature, more specifically in those where Dimensional Regularization does not apply. In the present contribution we extend the method to handle infrared divergences as well. We show that the essential steps which rendered Implicit Regularization adequate in the case of ultraviolet divergences have their counterpart for infrared ones. Moreover we show that a new scale appears, typically an infrared scale which is completely independent of the ultraviolet one. Examples are given.Comment: 9 pages, version to appear in Mod. Phys. Lett.

    Inelastic chaotic scattering on a Bose-Einstein condensate

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    We devise a microscopic scattering approach to probe the excitation spectrum of a Bose-Einstein condensate. We show that the experimentally accessible scattering cross section exhibits universal Ericson fluctuations, with characteristic properties rooted in the underlying classical field equations.Comment: 11 pages, 5 figure
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