51,854 research outputs found

    Realtime 3D graphics programming using the Quake3 engine

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    We present a lab assignment that accompanies a complete module called Real-time Graphics . The students task is to get familiar with content creation and programming a (previously) commercial 3D engine. In a first task, students have to create 3D content, which is integrated into the Quake3 engine. In a second task, the students have to implement a simple animation and finally add an impressive 3D graphics effect to the Quake3 engine. The lecture has been taught four times from 2004 to 2007. We present the assignment and report on experiences that we have gained

    On timelike and spacelike hard exclusive reactions

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    We show to next-to-leading order accuracy in the strong coupling alpha_s how the collinear factorization properties of QCD in the generalized Bjorken regime relate exclusive amplitudes for spacelike and timelike hadronic processes. This yields simple space--to--timelike relations linking the amplitudes for electroproduction of a photon or meson to those for photo- or meso-production of a lepton pair. These relations constitute a new test of the relevance of leading twist analyzes of experimental data.Comment: v2: major text revision; results, references, and author added; v3: matches the published version Phys. Rev. D86, rapid communication

    Probing GPDs in photoproduction processes at hadron colliders

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    Generalized parton distributions (GPDs) enter QCD factorization theorems for hard exclusive reactions. They encode rich information about hadron partonic structure. We explore a possibility to constrain GPDs in experiments at LHC considering two different exclusive processes: the timelike Compton scattering and the photoproduction of heavy vector mesons.Comment: 6 pages, 2 figures; presented at PHOTON 2015: International Conference on the Structure and the Interactions of the Photon, Novosibirsk, Russia, 15 - 19 June, 2015. arXiv admin note: text overlap with arXiv:1411.375

    Probing GPDs in Ultraperipheral Collisions

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    Ultraperipheral collisions in hadron colliders give new opportunites to investigate the hadron stucture through exclusive photoproduction processes. We describe the possibility of measuring the Generalized Parton Distributions in the Timelike Compton Scattering process and in the production of heavy vector meson.Comment: to appear in Proceedings Diffraction 2014, Primosten, Croatia, sept 10-16, 201

    GPDs in heavy meson production and Compton scattering

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    Exclusive processes of heavy meson production and spacelike and timelike deeply virtual Compton scattering allow us to investigate the hadron structure in terms of Generalized Parton Distributions (GPDs). We review recent developments in the NLO description of such processes.Comment: To appear in the proceedings of the 6th International Conference on the Physics Opportunities at an Electron-Ion Collide

    Monolithically integrated active optical devices

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    Considerations relevant to the monolithic integration of optical detectors, lasers, and modulators with high speed amplifiers are discussed. Some design considerations for representative subsystems in the GaAs-AlGaAs and GaInAs-InP materials systems are described. Results of a detailed numerical design of an electro-optical birefringent filter for monolithic integration with a laser diode is described, and early experimental results on monolithic integration of broadband MESFET amplifiers with photoconductive detectors are reported

    Defect free global minima in Thomson's problem of charges on a sphere

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    Given NN unit points charges on the surface of a unit conducting sphere, what configuration of charges minimizes the Coulombic energy ∑i>j=1N1/rij\sum_{i>j=1}^N 1/r_{ij}? Due to an exponential rise in good local minima, finding global minima for this problem, or even approaches to do so has proven extremely difficult. For \hbox{N=10(h2+hk+k2)+2N = 10(h^2+hk+k^2)+ 2} recent theoretical work based on elasticity theory, and subsequent numerical work has shown, that for N∼>500N \sim >500--1000 adding dislocation defects to a symmetric icosadeltahedral lattice lowers the energy. Here we show that in fact this approach holds for all NN, and we give a complete or near complete catalogue of defect free global minima.Comment: Revisions in Tables and Reference
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