36,175 research outputs found

    Southwest Research Institute assistance to NASA in biomedical areas of the technology utilization program Cumulative quarterly report, 1 Oct. 1967 - 31 Mar. 1968

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    Quarterly operations summary of center for selective dissemination of biomedical information within Technology Utilization progra

    Production of a Prompt Photon in Association with Charm at Next-to-Leading Order in QCD

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    A second order, O(αs2)O(\alpha ^2_s), calculation in perturbative quantum chromodynamics of the two particle inclusive cross section is presented for the reaction p+pˉγ+c+Xp +\bar{p}\rightarrow \gamma + c + X for large values of the transverse momentum of the prompt photon and charm quark. The combination of analytic and Monte Carlo integration methods used here to perform phase-space integrations facilitates imposition of photon isolation restrictions and other selections of relevance in experiments. Differential distributions are provided for various observables. Positive correlations in rapidity are predicted.Comment: 27 pages in RevTex plus 14 figures in one compressed PS fil

    Analytic Calculation of Prompt Photon plus Associated Heavy Flavor at Next-to-Leading Order in QCD

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    Contributions through second order, O(αs2)O(\alpha ^2_s), in perturbative quantum chromodynamics are calculated analytically for inclusive associated production of a prompt photon and a charm quark at large values of transverse momentum in high energy hadron-hadron collisions. Seven partonic subprocesses contribute at order αs2\alpha^2_s. We find important corrections to the lowest order, O(αs)O(\alpha_s), subprocess cgγcc g \rightarrow \gamma c. We demonstrate to what extent data from p+pˉγ+c+Xp +\bar{p}\rightarrow \gamma + c + X may serve to measure the charm quark density in the nucleon.Comment: 34 pages RevTex plus 9 figures submitted as uuencoded ps files; figures replaced and text revised to include one additional referenc

    Isolated Prompt Photon Production in Hadronic Final States of e+ee^+e^- Annihilation

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    We provide complete analytic expressions for the isolated prompt photon production cross section in e+ee^+e^- annihilation reactions through one-loop order in quantum chromodynamics (QCD) perturbation theory. Functional dependences on the isolation cone size δ\delta and isolation energy parameter ϵ\epsilon are derived. The energy dependence as well as the full angular dependence of the cross section on θγ\theta_\gamma are displayed, where θγ\theta_\gamma specifies the direction of the photon with respect to the e+ee^+e^- collision axis. We point out that conventional perturbative QCD factorization breaks down for isolated photon production in e+ee^+e^- annihilation reactions in a specific region of phase space. We discuss the implications of this breakdown for the extraction of fragmentation functions from e+ee^+e^- annihilation data and for computations of prompt photon production in hadron-hadron reactions.Comment: 54 pages RevTeX plus 19 postscript figures submitted together in one compressed fil

    Southwest Research Institute assistance to NASA in biomedical areas of the technology utilization program Quarterly progress report, 1 Jul. - 30 Sep. 1968

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    Southwest Research Institute activites in NASA technology utilization program for biomedical use, 1 Jul. - 30 Sep. 196

    Landau level spectroscopy of ultrathin graphite layers

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    Far infrared transmission experiments are performed on ultrathin epitaxial graphite samples in a magnetic field. The observed cyclotron resonance-like and electron-positron-like transitions are in excellent agreement with the expectations of a single-particle model of Dirac fermions in graphene, with an effective velocity of c* = 1.03 x 10^6 m/s.Comment: 4 pages 4 figures Slight revisions following referees' comments. One figure modifie

    Conceptual design study of a Harrier V/STOL research aircraft

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    MCAIR recently completed a conceptual design study to define modification approaches to, and derive planning prices for the conversion of a two place Harrier to a V/STOL control, display and guidance research aircraft. Control concepts such as rate damping, attitude stabilization, velocity command, and cockpit controllers are to be demonstrated. Display formats will also be investigated, and landing, navigation and guidance systems flight tested. The rear cockpit is modified such that it can be quickly adapted to faithfully simulate the controls, displays and handling qualities of a Type A or Type B V/STOL. The safety pilot always has take command capability. The modifications studied fall into two categories: basic modifications and optional modifications. Technical descriptions of the basic modifications and of the optional modifications are presented. The modification plan and schedule as well as the test plan and schedule are presented. The failure mode and effects analysis, aircraft performance, aircraft weight, and aircraft support are discussed
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