25,487 research outputs found

    Muon anomalous magnetic moment from effective supersymmetry

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    We present a detailed analysis on the possible maximal value of the muon (g-2) (= 2 a_mu) within the context of effective SUSY models with R parity conservation. First of all, the mixing among the second and the third family sleptons can contribute at one loop level to the a_mu(SUSY) and tau -> mu gamma simultaneously. One finds that the a_mu(SUSY) can be as large as (10-20)*10^-10 for any tan beta, imposing the upper limit on the tau -> mu gamma branching ratio. Furthermore, the two-loop Barr-Zee type contributions to a_mu(SUSY) can be significant for large tan beta, if a stop is light and mu and A_t are large enough (O(1) TeV). In this case, it is possible to have a_mu(SUSY) upto O(10)*10^-10 without conflicting with tau -> l gamma. We conclude that the possible maximal value for a_mu(SUSY) is about 20*10^-10 for any tan beta. Therefore the BNL experiment on the muon a_mu can exclude the effective SUSY models only if the measured deviation is larger than \sim 30*10^-10.Comment: 10 pages, 3 figure

    Contribution of b→sggb \to sgg through the QCD anomaly in exclusive decays B±→(η′,η)(K±,K∗±)B^{\pm}\to (\eta^{\prime},\eta)(K^{\pm}, K^{*\pm}) and B0→(η′,η)(K0,K∗0)B^{0}\to (\eta^{\prime},\eta)(K^{0},K^{*0})

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    We compute the decay rates for the exclusive decays B±→(η′,η)(K±,K∗±)B^{\pm} \to (\eta^{\prime},\eta) (K^{\pm}, K^{*\pm}) and B0→(η′,η)(K0,K∗0)B^{0}\to (\eta^{\prime},\eta) (K^{0}, K^{*0}) in a QCD-improved factorization framework by including the contribution from the process b→sgg→s(η′,η)b\to sgg \to s (\eta^{\prime}, \eta) through the QCD anomaly. This method provides an alternative estimate of the contribution b→sccˉ→s(η,η′)b \to s c\bar{c} \to s(\eta,\eta^\prime) to these decays as compared to the one using the intrinsic charm content of the η′\eta^{\prime} and η\eta mesons determined through the decays J/ψ→(η,η′,ηc)γJ/\psi \to (\eta,\eta^\prime ,\eta_c) \gamma. The resulting branching ratios are compared with the CLEO data on B±→η′K±B^{\pm} \to \eta^{\prime} K^{\pm} and B0→η′K0B^{0} \to \eta^{\prime} K^{0} and predictions are made for the rest.Comment: 16 pages including 4 postscript figures; uses epsfig. The most recent branching ratios from CLEO, ref. [5], are taken into account. The theory part is unchange

    Application of Finite Viscoelastic Theory to the Deformation of Rubberlike Materials I. Uniaxial Stress Relaxation Data

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    In this report the constitutive equation for finite viscoelastic materials will be postulated as the sum of equilibrium terms and integral terms which describe the viscoelastic behavior of the materials and vanish when the equilibrium state is reached or when the materials have always been at rest. It is also our purpose i) to show how the twelve relaxation functions are reduced to two independent ones in the case that the material has Mooney-Rivlin elastic behavior and that all the relaxation functions depend only on time, ii) to display the mechanics of evaluating the two non-zero relaxation functions from data obtained from uniaxial stress relaxation tests

    Two-point motional Stark effect diagnostic for Madison Symmetric Torus

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    A high-precision spectral motional Stark effect (MSE) diagnostic provides internal magnetic field measurements for Madison Symmetric Torus (MST) plasmas. Currently, MST uses two spatial views-on the magnetic axis and on the midminor (off-axis) radius, the latter added recently. A new analysis scheme has been developed to infer both the pitch angle and the magnitude of the magnetic field from MSE spectra. Systematic errors are reduced by using atomic data from atomic data and analysis structure in the fit. Reconstructed current density and safety factor profiles are more strongly and globally constrained with the addition of the off-axis radius measurement than with the on-axis one only

    Locating faults in MANET-hosted software systems

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    We present a method to locate faults in service-based software systems hosted on mobile ad hoc networks (MANETs). In such systems, computations are structured as interdependent services distributed across the network, collaborating to satisfy client requests. Faults, which may occur at either or both the service and network layers, propagate by cascading through some subset of the services, from their root causes back to the clients that initiate requests. Fault localization in this environment is especially challenging because the systems are typically subject to a wider variety and higher incidence of faults than those deployed in fixed networks, the resources available to collect and store analysis data are severely limited, and many of the sources of faults are by their nature transient. Our method makes use of service-dependence and fault data that are harvested in the network through decentralized, run-time observations of service interactions and fault symptoms. We have designed timing- and Bayesian-based reasoning techniques to analyze the data in the context of a specific fault propagation model. The analysis provides a ranked list of candidate fault locations. Through extensive simulations, we evaluate the performance of our method in terms of its accuracy in correctly ranking root causes under a wide range of operational conditions

    Color-octet mechanism and J/psi polarization at LEP

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    Polarized heavy quarkonium productions in Z0Z^0 decays are considered. We find that polarizations of the produced quarkonia are independent of that of the parent Z^0 provided that one considers the energy distribution or the total production rate. Produced J/psi's via the color-octet and the color- singlet mechanisms are expected to be 19% and 29% longitudinally polarized, respectively. The energy dependence of eta_{1,8}(x)=\frac{dGamma_{1,8}^L}{dx} /\frac{dGamma_{1,8}}{d x} is very sensitive to the production mechanism, and therefore the measurement of \eta(x)_exp will be an independent probe of the color-octet mechanism.Comment: 15 pages, minor changes, version to be published in Phys. Rev.

    Dependence of lepton pair emission on EoS and initial state

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    We present results from a hydrodynamic calculation for thermal emission of lepton pairs in central lead-lead collisions at the CERN SPS energy. Dependence of the emission on the initial conditions and Equation of State (EoS) is considered and the spectra are compared with CERES data and calculated distribution of Drell--Yan pairs.Comment: 4 pages, includes 4 ps-figures, talk at Quark Matter'97, Tsukuba, Japa

    The evolution of gregariousness in parasitoid wasps

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    Data are assembled on the clutch-size strategies adopted by extant species of parasitoid wasp. These data are used to reconstruct the history of clutch-size evolution in the group using a series of plausible evolutionary assumptions. Extant families are either entirely solitary, both solitary and gregarious, or else clutch size is unknown. Parsimony analysis suggests that the ancestors of most families were solitary, a result which is robust to different phylogenetic relationships and likely data inadequacies. This implies that solitariness was ubiquitous throughout the initial radiation of the group, and that transitions to gregariousness have subsequently occurred a minimum of 43 times in several, but not all lineages. Current data suggest that species-rich and small-bodied lineages are more likely to have evolved gregariousness, and contain more species with small gregarious brood sizes. I discuss the implications of these data for clutch-size theory

    Fundamental Studies Relating to the Mechanical Behavior of Solid Propellants, Rocket Grains and Rocket Motors

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    During the past three years, the mechanical testing of solid propellants, solid rocket grains, and solid rocket motors under idealized conditions has been receiving increased attention. Today it is not uncommon to see a multitude of new techniques and analyses being investigated. One may expect to see dummy propellant prepared with glass bead filler to observe its dilatation to rupture; to ink circles, rectangular g rids at various critical areas on a grain surface, and to observe the distortion of these grids as a result of thermal cycling and/or slump; to subj e ct rectangular parallel-opipedal-shaped specimens to both torsion and biaxial tension as well as hydrostatic compression and parallel-plate tension; to apply theories of large elastic strain, and non-linear viscoelasticity; to search for an isotropic failure criterion as well as a crack propagation criterion. In short the mechanics of propellant behavior from small deformation all the way to fracture initiation and propagation has become quite sophisticated. Gradually the results of this testing and their thinking are being integrated in a logical scheme of analysis which is being passed along to the engineer and being used in predicting performance of rocket motors. This particular program will pertain to four areas: 1) The characterization of polyurethane propellant behavior out to fracture initiation in terms of large strain theory. 2) The development of a failure criterion and crack propagation criteria for said materials. 3) The generation, where possible, of macroscopic mechanical parameters in terms of molecular parameters. 4} The solution of certain stress problems, in both linear and non-linear theory, which are prerequisite to engineering applications. As such it is part of a continuing research study of structural integrity problems in solid propellant rocket motors being conducted under the general direction of Dr. M. L. Williams in the Guggenheim Aeronautical Laboratory. This preliminary report is intended as an interim working document to be circulated for the purpose of stimulating discussion
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