8,529 research outputs found

    Influence of retardation effects on 2D magnetoplasmon spectrum

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    Within dissipationless limit the magnetic field dependence of magnetoplasmon spectrum for unbounded 2DEG system found to intersect the cyclotron resonance line, and, then approaches the frequency given by light dispersion relation. Recent experiments done for macroscopic disc-shape 2DEG systems confirm theory expectations.Comment: 2 pages,2 figure

    Factorization Structure of Gauge Theory Amplitudes and Application to Hard Scattering Processes at the LHC

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    Previous work on electroweak radiative corrections to high energy scattering using soft-collinear effective theory (SCET) has been extended to include external transverse and longitudinal gauge bosons and Higgs bosons. This allows one to compute radiative corrections to all parton-level hard scattering amplitudes in the standard model to NLL order, including QCD and electroweak radiative corrections, mass effects, and Higgs exchange corrections, if the high-scale matching, which is suppressed by two orders in the log counting, and contains no large logs, is known. The factorization structure of the effective theory places strong constraints on the form of gauge theory amplitudes at high energy for massless and massive gauge theories, which are discussed in detail in the paper. The radiative corrections can be written as the sum of process-independent one-particle collinear functions, and a universal soft function. We give plots for the radiative corrections to q qbar -> W_T W_T, Z_T Z_T, W_L W_L, and Z_L H, and gg -> W_T W_T to illustrate our results. The purely electroweak corrections are large, ranging from 12% at 500 GeV to 37% at 2 TeV for transverse W pair production, and increasing rapidly with energy. The estimated theoretical uncertainty to the partonic (hard) cross-section in most cases is below one percent, smaller than uncertainties in the parton distribution functions (PDFs). We discuss the relation between SCET and other factorization methods, and derive the Magnea-Sterman equations for the Sudakov form factor using SCET, for massless and massive gauge theories, and for light and heavy external particles.Comment: 44 pages, 30 figures. Refs added, typos fixed. ZL ZL plots removed because of a possible subtlet

    Smart Hospital Management System: An integration of enterprise level solutions utilising open group architecture framework (TOGAF)

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    A significant portion of the Hospital Information Systems currently consists of various individual legacy applications that have to be integrated, to deliver a more unified solution. The performance, reliability and other factors of these applications can alter the performance, reliability and other characteristics of integrated Solution, the Smart Hospital Management System (SHS). The actual evaluation of these parameters of these applications is outside the scope of this document. The SHS being an infrastructure component relies heavily on the actual resources made available to it for its proper functioning, operation and maintenance. This article aims to deliver an approach in architecting solutions which can be utilised as framework to address common issues in integration of enterprise level solutions. The methodologies discussed in TOGAF version 9 are utilised to demonstrate the feasibility of proposed solution. This paper introduces the problem space/scenarios, constraints, requirements, enablers, risks, sample legacy application architectures and proposed integration solution presented with TOGAF components. The growing number of waiting lists, rising pressure on medical professionals and accountability for medical negligence are only part of the motivation to take initiative towards holds a core model integration strategy in various legacy infrastructure systems. © 2010 IEEE

    Demonstration of the asymmetric lateral Casimir force between corrugated surfaces in the nonadditive regime

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    The measurement of the lateral Casimir force between two aligned sinusoidally corrugated Au-coated surfaces has been performed in the nonadditive regime. The use of deeper corrugations also allowed to demonstrate an asymmetry in the phase dependences of the lateral Casimir force, as predicted earlier. The measurement data are found to be in excellent agreement with the exact theoretical results computed at T=300 K including effect of real material properties. The deviations between the exact theory and the proximity force approximation are quantified. The obtained results are topical for applications in nanomachines.Comment: 9 pages, 3 figure

    Electroweak Corrections using Effective Field Theory: Applications to the LHC

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    Electroweak Sudakov logarithms at high energy, of the form alpha/sin^2 theta_W^n log^m s/M_{Z,W}^2, are summed using effective theory (EFT) methods. The exponentiation of Sudakov logarithms and factorization is discussed in the EFT formalism. Radiative corrections are computed to scattering processes in the standard model involving an arbitrary number of external particles. The computations include non-zero particle masses such as the t-quark mass, electroweak mixing effects which lead to unequal W and Z masses and a massless photon, and Higgs corrections proportional to the top quark Yukawa coupling. The structure of the radiative corrections, and which terms are summed by the EFT renormalization group is discussed in detail. The omitted terms are smaller than 1%. We give numerical results for the corrections to dijet production, dilepton production, t-\bar t production, and squark pair production. The purely electroweak corrections are significant -- about 15% at 1 TeV, increasing to 30% at 5 TeV, and they change both the scattering rate and angular distribution. The QCD corrections (which are well-known) are also computed with the EFT. They are much larger -- about a factor of four at 1 TeV, increasing to a factor of thirty at 5 TeV. Mass effects are also significant; the q \bar q -> t \bar t rate is enchanced relative to the light-quark production rate by 40%.Comment: Additional details added on exponentiation, and the form of the Sudakov series. Figures darkened to print better. 40 pages, 40 figure

    Soft-Collinear Factorization and Zero-Bin Subtractions

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    We study the Sudakov form factor for a spontaneously broken gauge theory using a (new) Delta -regulator. To be well-defined, the effective theory requires zero-bin subtractions for the collinear sectors. The zero-bin subtractions depend on the gauge boson mass M and are not scaleless. They have both finite and 1/epsilon contributions, and are needed to give the correct anomalous dimension and low-scale matching contributions. We also demonstrate the necessity of zero-bin subtractions for soft-collinear factorization. We find that after zero-bin subtractions the form factor is the sum of the collinear contributions 'minus' a soft mass-mode contribution, in agreement with a previous result of Idilbi and Mehen in QCD. This appears to conflict with the method-of-regions approach, where one gets the sum of contributions from different regions.Comment: 9 pages, 5 figures. V2:ref adde

    (D* to D + gamma) and (B* to B + gamma) as derived from QCD Sum Rules

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    The method of QCD sum rules in the presence of the external electromagnetic FμνF_{\mu\nu} field is used to analyze radiative decays of charmed or bottomed mesons such as D∗→DγD^{\ast}\to D\gamma and B∗→BγB^{\ast}\to B\gamma, with the susceptibilities obtained previously from the study of baryon magnetic moments. Our predictions on D∗D^{\ast} decays agree very well with the experimental data. There are differences among the various theoretical predictions on B∗B^{\ast} decays but the data are not yet available.Comment: 11 pages, Late

    Vector, Axial, Tensor and Pseudoscalar Vacuum Susceptibilities

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    Using a recently developed three-point formalism within the method of QCD Sum Rules we determine the vacuum susceptibilities needed in the two-point formalism for the coupling of axial, vector, tensor and pseudoscalar currents to hadrons. All susceptibilities are determined by the space-time scale of condensates, which is estimated from data for deep inelastic scattering on nucleons

    Constraints on Primordial Nongaussiantiy from the High-Redshift Cluster MS1054--03

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    The implications of the massive, X-ray selected cluster of galaxies MS1054--03 at z=0.83z=0.83 are discussed in light of the hypothesis that the primordial density fluctuations may be nongaussian. We generalize the Press-Schechter (PS) formalism to the nongaussian case, and calculate the likelihood that a cluster as massive as MS1054 would appear in the EMSS. The probability of finding an MS1054-like cluster depends only on \omegam and the extent of primordial nongaussianity. We quantify the latter by adopting a specific functional form for the PDF, denoted ψλ,\psi_\lambda, which tends to Gaussianity for λ≫1,\lambda\gg 1, and show how λ\lambda is related to the more familiar statistic T,T, the probability of ≥3σ\ge 3\sigma fluctuations for a given PDF relative to a Gaussian. We find that Gaussian initial density fluctuations are consistent with the data on MS1054 only if \omegam\simlt 0.2. For \omegam\ge 0.25 a significant degree of nongaussianity is required, unless the mass of MS1054 has been substantially overestimated by X-ray and weak lensing data. The required amount of nongaussianity is a rapidly increasing function of \omegam for 0.25 \le \omegam \le 0.45, with λ≤1\lambda \le 1 (T \simgt 7) at the upper end of this range. For a fiducial \omegam=0.3, \omegal=0.7 universe, favored by several lines of evidence we obtain an upper limit λ≤10,\lambda \le 10, corresponding to a T≥3.T\ge 3. This finding is consistent with the conclusions of Koyama, Soda, & Taruya (1999), who applied the generalized PS formalism to low (z\simlt 0.1) and intermediate (z\simlt 0.6) redshift cluster data sets.Comment: 15 pages, 11 figures, submitted to the Astrophysical Journal, uses emulateapj.st

    Role of material properties and mesostructure on dynamic deformation and shear instability in Al-W granular composites

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    Dynamic experiments with Al-W granular/porous composites revealed qualitatively different behavior with respect to shear localization depending on bonding between Al particles. Two-dimensional numerical modeling was used to explore the mesomechanics of the large strain dynamic deformation in Al-W granular/porous composites and explain the experimentally observed differences in shear localization between composites with various mesostructures. Specifically, the bonding between the Al particles, the porosity, the roles of the relative particle sizes of Al and W, the arrangements of the W particles, and the material properties of Al were investigated using numerical calculations. It was demonstrated in simulations that the bonding between the "soft" Al particles facilitated shear localization as seen in the experiments. Numerical calculations and experiments revealed that the mechanism of the shear localization in granular composites is mainly due to the local high strain flow of "soft" Al around the "rigid" W particles causing localized damage accumulation and subsequent growth of the meso/macro shear bands/cracks. The "rigid" W particles were the major geometrical factor determining the initiation and propagation of "kinked" shear bands in the matrix of "soft" Al particles, leaving some areas free of extensive plastic deformation as observed in experiments and numerical calculations.Comment: 10 pages, 14 figures, submitted to Journal of Applied Physic
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