4,924 research outputs found

    Flow field prediction and analysis study for project RAM B3 Final report

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    Flow field properties in shock layer surrounding Ram B3 vehicl

    Bounds on Dimension Reduction in the Nuclear Norm

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    \newcommand{\schs}{\scriptstyle{\mathsf{S}}_1} For all n1n \ge 1, we give an explicit construction of m×mm \times m matrices A1,,AnA_1,\ldots,A_n with m=2n/2m = 2^{\lfloor n/2 \rfloor} such that for any dd and d×dd \times d matrices A1,,AnA'_1,\ldots,A'_n that satisfy \|A'_i-A'_j\|_{\schs} \,\leq\, \|A_i-A_j\|_{\schs}\,\leq\, (1+\delta) \|A'_i-A'_j\|_{\schs} for all i,j{1,,n}i,j\in\{1,\ldots,n\} and small enough δ=O(nc)\delta = O(n^{-c}), where c>0c> 0 is a universal constant, it must be the case that d2n/21d \ge 2^{\lfloor n/2\rfloor -1}. This stands in contrast to the metric theory of commutative p\ell_p spaces, as it is known that for any p1p\geq 1, any nn points in p\ell_p embed exactly in pd\ell_p^d for d=n(n1)/2d=n(n-1)/2. Our proof is based on matrices derived from a representation of the Clifford algebra generated by nn anti-commuting Hermitian matrices that square to identity, and borrows ideas from the analysis of nonlocal games in quantum information theory.Comment: 16 page

    On kernel engineering via Paley–Wiener

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    A radial basis function approximation takes the form s(x)=k=1nakϕ(xbk),xRd,s(x)=\sum_{k=1}^na_k\phi(x-b_k),\quad x\in {\mathbb{R}}^d, where the coefficients a 1,…,a n are real numbers, the centres b 1,…,b n are distinct points in ℝ d , and the function φ:ℝ d →ℝ is radially symmetric. Such functions are highly useful in practice and enjoy many beautiful theoretical properties. In particular, much work has been devoted to the polyharmonic radial basis functions, for which φ is the fundamental solution of some iterate of the Laplacian. In this note, we consider the construction of a rotation-invariant signed (Borel) measure μ for which the convolution ψ=μ φ is a function of compact support, and when φ is polyharmonic. The novelty of this construction is its use of the Paley–Wiener theorem to identify compact support via analysis of the Fourier transform of the new kernel ψ, so providing a new form of kernel engineering

    Bounds on Dimension Reduction in the Nuclear Norm

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    For all n ≥ 1, we give an explicit construction of m × m matrices A_1,…,A_n with m = 2^([n/2]) such that for any d and d × d matrices A′_1,…,A′_n that satisfy ∥A_′i−A′_j∥S_1 ≤ ∥A_i−A_j∥S_1 ≤ (1+δ)∥A′_i−A′_j∥S_1 for all i,j∈{1,…,n} and small enough δ = O(n^(−c)), where c > 0 is a universal constant, it must be the case that d ≥ 2^([n/2]−1). This stands in contrast to the metric theory of commutative ℓ_p spaces, as it is known that for any p ≥ 1, any n points in ℓ_p embed exactly in ℓ^d_p for d = n(n−1)/2. Our proof is based on matrices derived from a representation of the Clifford algebra generated by n anti-commuting Hermitian matrices that square to identity, and borrows ideas from the analysis of nonlocal games in quantum information theory

    The Detection of Ionizing Radiation by Plasma Panel Sensors: Cosmic Muons, Ion Beams and Cancer Therapy

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    The plasma panel sensor is an ionizing photon and particle radiation detector derived from PDP technology with high gain and nanosecond response. Experimental results in detecting cosmic ray muons and beta particles from radioactive sources are described along with applications including high energy and nuclear physics, homeland security and cancer therapeuticsComment: Presented at SID Symposium, June 201

    A Systematic Extended Iterative Solution for QCD

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    An outline is given of an extended perturbative solution of Euclidean QCD which systematically accounts for a class of nonperturbative effects, while allowing renormalization by the perturbative counterterms. Proper vertices Gamma are approximated by a double sequence Gamma[r,p], with r the degree of rational approximation w.r.t. the QCD mass scale Lambda, nonanalytic in the coupling g, and p the order of perturbative corrections in g-squared, calculated from Gamma[r,0] - rather than from the perturbative Feynman rules Gamma(0)(pert) - as a starting point. The mechanism allowing the nonperturbative terms to reproduce themselves in the Dyson-Schwinger equations preserves perturbative renormalizability and is tied to the divergence structure of the theory. As a result, it restricts the self-consistency problem for the Gamma[r,0] rigorously - i.e. without decoupling approximations - to the superficially divergent vertices. An interesting aspect of the scheme is that rational-function sequences for the propagators allow subsequences describing short-lived excitations. The method is calculational, in that it allows known techniques of loop computation to be used while dealing with integrands of truly nonperturbative content.Comment: 48 pages (figures included). Scope of replacement: correction of a technical defect; no changes in conten

    Supersymmetric constraints from Bs -> mu+mu- and B -> K* mu+mu- observables

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    We study the implications of the recent LHCb limit and results on Bs -> mu+mu- and B -> K* mu+mu- observables in the constrained SUSY scenarios. After discussing the Standard Model predictions and carefully estimating the theoretical errors, we show the constraining power of these observables in CMSSM and NUHM. The latest limit on BR(Bs -> mu+mu-), being very close to the SM prediction, constrains strongly the large tan(beta) regime and we show that the various angular observables from B -> K* mu+mu- decay can provide complementary information in particular for moderate tan(beta) values.Comment: 30 pages, 14 figure

    Spin-Dependent Twist-Four Matrix Elements from g_1 Data in the Resonance Region

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    Matrix elements of spin-dependent twist-four operators are extracted from recent data on the spin-dependent g_1 structure function of the proton and deuteron in the resonance region. We emphasize the need to include the elastic contributions to the first moments of the structure functions at Q^2 < 2 GeV^2. The coefficients of the 1/Q^2 corrections to the Ellis-Jaffe sum rules are found to be 0.04 \pm 0.02 and 0.03 \pm 0.04 GeV^2 for the proton and neutron, respectively.Comment: 10 pages REVTeX, 4 figure

    Supersymmetric top and bottom squark production at hadron colliders

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    The scalar partners of top and bottom quarks are expected to be the lightest squarks in supersymmetric theories, with potentially large cross sections at hadron colliders. We present predictions for the production of top and bottom squarks at the Tevatron and the LHC, including next-to-leading order corrections in supersymmetric QCD and the resummation of soft gluon emission at next-to-leading-logarithmic accuracy. We discuss the impact of the higher-order corrections on total cross sections and transverse-momentum distributions, and provide an estimate of the theoretical uncertainty due to scale variation and the parton distribution functions.Comment: 29 pages, 6 figure
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