14,315,023 research outputs found

    Exclusive B(K,ρ)γB \to (K^*, \rho) \gamma decays in the general two-Higgs-doublet models

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    By employing the QCD factorization approach, we calculated the next-to-leading order new physics contributions to the branching ratios, CP asymmetries, isospin and U-spin symmetry breaking of the exclusive decays BVγB \to V \gamma (V=K,ρV=K^*, \rho), induced by the charged Higgs penguins in the general two-Higgs-doublet models. Within the considered parameter space, we found that (a) the new physics corrections to the observables are generally small in the model I and model III-A, moderate in model II, but large in model III-B; (b) from the well measured branching ratios and upper limits, a lower bound of \mhp > 200 GeV in model II was obtained, while the allowed range of \mhp in model III-B is 226 \leq \mhp \leq 293 GeV; these bounds are comparable with those from the inclusive BXsγB \to X_s \gamma decay; (c)the NLO Wilson coefficient C7(mb)C_7(m_b) in model III-B is positive and disfavered by the measured value of isospin symmetry breaking Δ0exp(Kγ)=(3.9±4.8)\Delta_{0-}^{exp} (K^*\gamma) = (3.9 \pm 4.8)%, but still can not be excluded if we take the large errors into account; (d) the CP asymmetry \acp(B \to \rho \gamma) in model III-B has an opposite sign with the one in the standard model (SM), which may be used as a good observable to distinguish the SM from model III-B; (e) the isospin symmetry breaking Δ(ργ)\Delta(\rho\gamma) is less than 10% in the region of γ=[4070]\gamma = [ 40 \sim 70]^\circ preferred by the global fit result, but can be as large as 20 to 40% in the regions of γ10\gamma \leq 10^\circ and γ120\gamma \geq 120^\circ. The SM and model III-B predictions for Δ(ργ)\Delta(\rho \gamma) are opposite in sign for small or large values of the CKM angles; (f) the U-spin symmetry breaking ΔU(K,ρ)\Delta U(K^*,\rho) in the SM and the general two-Higgs-doublet models is generally small in size: 107\sim 10^{-7}.Comment: Revtex, 38 pages with 14 eps figures, minor correction

    Antimicrobials: a global alliance for optimizing their rational use in intra-abdominal infections (AGORA)

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    Intra-abdominal infections (IAI) are an important cause of morbidity and are frequently associated with poor prognosis, particularly in high-risk patients. The cornerstones in the management of complicated IAIs are timely effective source control with appropriate antimicrobial therapy. Empiric antimicrobial therapy is important in the management of intra-abdominal infections and must be broad enough to cover all likely organisms because inappropriate initial antimicrobial therapy is associated with poor patient outcomes and the development of bacterial resistance. The overuse of antimicrobials is widely accepted as a major driver of some emerging infections (such as C. difficile), the selection of resistant pathogens in individual patients, and for the continued development of antimicrobial resistance globally. The growing emergence of multi-drug resistant organisms and the limited development of new agents available to counteract them have caused an impending crisis with alarming implications, especially with regards to Gram-negative bacteria. An international task force from 79 different countries has joined this project by sharing a document on the rational use of antimicrobials for patients with IAIs. The project has been termed AGORA (Antimicrobials: A Global Alliance for Optimizing their Rational Use in Intra-Abdominal Infections). The authors hope that AGORA, involving many of the world's leading experts, can actively raise awareness in health workers and can improve prescribing behavior in treating IAIs

    Measurement of the multi-TeV neutrino cross section with IceCube using Earth absorption

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    Neutrinos interact only very weakly, so they are extremely penetrating. However, the theoretical neutrino-nucleon interaction cross section rises with energy such that, at energies above 40 TeV, neutrinos are expected to be absorbed as they pass through the Earth. Experimentally, the cross section has been measured only at the relatively low energies (below 400 GeV) available at neutrino beams from accelerators \cite{Agashe:2014kda, Formaggio:2013kya}. Here we report the first measurement of neutrino absorption in the Earth, using a sample of 10,784 energetic upward-going neutrino-induced muons observed with the IceCube Neutrino Observatory. The flux of high-energy neutrinos transiting long paths through the Earth is attenuated compared to a reference sample that follows shorter trajectories through the Earth. Using a fit to the two-dimensional distribution of muon energy and zenith angle, we determine the cross section for neutrino energies between 6.3 TeV and 980 TeV, more than an order of magnitude higher in energy than previous measurements. The measured cross section is 1.300.19+0.211.30^{+0.21}_{-0.19} (stat.) 0.43+0.39^{+0.39}_{-0.43} (syst.) times the prediction of the Standard Model \cite{CooperSarkar:2011pa}, consistent with the expectation for charged and neutral current interactions. We do not observe a dramatic increase in the cross section, expected in some speculative models, including those invoking new compact dimensions \cite{AlvarezMuniz:2002ga} or the production of leptoquarks \cite{Romero:2009vu}.Comment: Preprint version of Nature paper 10.1038/nature2445

    A 2D integrable axion model and Target space duality

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    A review is given on the recently proposed two dimensional axion model (O(3) sigma-model with a dynamical Hopf-term) and the T-duality relating it to the SU(2)xU(1) symmetric anisotropic sigma-model. Strong evidence is presented for the correctness of the proposed S-matrix for both models comparing perturbative and Thermodynamical Bethe Ansatz calculations for different types of free energies. This also provides a very stringent test of the validity of T-duality transformation at the quantum level. The quantum non-integrability of the O(3) sigma-model with a non-dynamical Hopf-term, in contradistinction to the axion model, is illustrated by calculating the 2-->3 particle production amplitude to lowest order.Comment: LateX, 21 pages, 1 figure. Improved version of a talk delivered at the Johns Hopkins workshop `Non-perturbative QFT Methods and their Applications', Budapest, 200

    Conformal Boundary Conditions and what they teach us

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    The question of boundary conditions in conformal field theories is discussed, in the light of recent progress. Two kinds of boundary conditions are examined, along open boundaries of the system, or along closed curves or ``seams''. Solving consistency conditions known as Cardy equation is shown to amount to the algebraic problem of finding integer valued representations of (one or two copies of) the fusion algebra. Graphs encode these boundary conditions in a natural way, but are also relevant in several aspects of physics ``in the bulk''. Quantum algebras attached to these graphs contain information on structure constants of the operator algebra, on the Boltzmann weights of the corresponding integrable lattice models etc. Thus the study of boundary conditions in Conformal Field Theory offers a new perspective on several old physical problems and offers an explicit realisation of recent mathematical concepts.Comment: Expanded version of lectures given at the Summer School and Conference Nonperturbative Quantum Field Theoretic Methods and their Applications, August 2000, Budapest, Hungary. 35 page

    Large-time Behavior of Solutions to the Inflow Problem of Full Compressible Navier-Stokes Equations

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    Large-time behavior of solutions to the inflow problem of full compressible Navier-Stokes equations is investigated on the half line R+=(0,+)R^+ =(0,+\infty). The wave structure which contains four waves: the transonic(or degenerate) boundary layer solution, 1-rarefaction wave, viscous 2-contact wave and 3-rarefaction wave to the inflow problem is described and the asymptotic stability of the superposition of the above four wave patterns to the inflow problem of full compressible Navier-Stokes equations is proven under some smallness conditions. The proof is given by the elementary energy analysis based on the underlying wave structure. The main points in the proof are the degeneracies of the transonic boundary layer solution and the wave interactions in the superposition wave.Comment: 27 page
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