12,911 research outputs found

    Improved non-perturbative renormalization without cNGIc_{NGI}

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    Recently, a method for O(a) improvement of composite operators has been proposed which uses the large momentum behavior of fixed gauge quark and gluon correlation functions (G. Martinelli et al., hep-lat/0106003). A practical problem with this method is that a particular improvement coefficient, cNGIc_{NGI}, which has a gauge non-covariant form, is difficult to determine. Here I work out the size of the errors made in improvement coefficients and physical quantities if one does not include the cNGIc_{NGI} term.Comment: 3 pages. Lattice2001(improvement

    Renormalization Constants using Quark States in Fixed Gauge

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    We present a status report on our calculation of the renormalization constants for the quark bilinears in quenched (O(a)) improved Wilson theory at (beta=6.4) using quark states in Landau gauge.Comment: 4 pages. Contribution to LATTICE00(Improvement), August, 2000, Bangalore Indi

    Lattice computation of structure functions

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    Recent lattice calculations of hadron structure functions are described.Comment: Plenary talk presented at LATTICE96, LaTeX, 7 pages, 5 figures, espcrc2.sty and epsfig.sty include

    Hermite Calculus

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    We develop a new method of umbral nature to treat blocks of Her mite and of Hermite like poly- nomials as independent algebraic quantities. The Calculus we propose allows the formulation of a number of ”practical rules” allowing significant simplific ations in computational problem

    Heavy-heavy form factors and generalized factorization

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    We reanalyze B -> D pi and B -> K J/psi data to extract a set of parameters which give the relevant hadronic matrix elements in terms of factorized amplitudes. Various sources of theoretical uncertainties are studied, in particular those depending on the model adopted for the form factors. We find that the fit to the B -> D pi branching ratios substantially depends on the model describing the Isgur-Wise function and on the value of its slope. This dependence can be reduced by substituting the BR(B -> D pi) with suitable ratios of non-leptonic to differential semileptonic BRs. In this way, we obtain a model-independent determination of these parameters. Using these results, the B -> D form factors at q^2=M_pi^2 can be extracted from a fit of the BR(B -> D pi). The comparison between the form factors obtained in this way and the corresponding measurements in semileptonic decays can be used as a test of (generalized) factorization free from the uncertainties due to heavy-heavy form factor modeling. Finally, we present predictions for yet-unmeasured D pi and D K branching ratios and extract f_{D_s} and f_{D_s^*} from B -> DD_s decays. We find f_{D_s} = 270 +- 45 MeV and f_{D_s^*}=260 +- 40 MeV, in good agreement with recent measurements and lattice calculations.Comment: 20 pages, 16 ps/eps files, uses epsfig.sty; exp. numbers update

    Lightweight multiple output converter development

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    A high frequency, multiple output power conditioner was developed and breadboarded using an eight-stage capacitor diode voltage multiplier to provide +1200 Vdc, and a three-stage for -350 Vdc. In addition, two rectifier bridges were capacitively coupled to the eight-stage multiplier to obtain 0.5 and 0.65 a dc constant current outputs referenced to +1200 Vdc. Total power was 120 watts, with an overall efficiency of 85 percent at the 80 kHz operating frequency. All outputs were regulated to three percent or better, with complete short circuit protection. The power conditioner component weight and efficiency were compared to the equivalent four outputs of the 10 kHz conditioner for the 8 cm ion engine. Weight reduction for the four outputs was 557 grams; extrapolated in the same ratio to all nine outputs, it would be 1100 to 1400 grams

    Theoretical study of the mechanisms of fatigue in photomultipliers, phase 2 Final report

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    Fatigue testing of photomultipliers with gallium phosphide dynode

    Metafisica ingenua. Il problema delle categorie in Paolo Bozzi e Carl Stumpf

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    The paper compares the ideas developed by Bozzi and Stumpf with regard to unity, identity, and causality. Although Bozzi’s formulation is independent from the one made by Stumpf in his Erkenntnislehre, these two positions share the same innovative importance granted to perceptual experience and to the problem of the origin of categories. Thus, despite different levels of awareness and formalization, in both authors we see the features of what we can call – analogous- ly to Bozzi’s naïve physics – a “naïve metaphysics”, at whose core lie the refusal of intellectualism, and the determination of the origin of categories in the concrete stream of perception

    Musica e Weltanschauung. Opera musicale, filosofia, cultura

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    Can music express the world-view of a certain composer, or of a certain historical era – and how? In 19th Century, the wide-ranging philosophical implications of this question raised an intriguing quarrel between the formalists’ scepticism as to this point and their various opponents. Starting from the case study of the German psychologist and philosopher of music Georg Anschütz, it is argued that allowing for a systematic link of music and the world-views easily turns into the far more demanding claim that music is the best and perhaps the only way to express them properly. In turn, this attitude sits well with the tendency to think of music hearing as a disembodied process, hinting at the deep dimension of synesthesia rather than to that of music as a cultural phenomenon, in Erich Hornbostel’s sense
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