25,386 research outputs found

    Contributions to the width difference in the neutral DD system from hadronic decays

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    Recent studies of several multi-body D0D^0 meson decays have revealed that the final states are dominantly CPCP-even. However, the small value of the width difference between the two physical eigenstates of the D0D^0-D‾0\overline{D}{}^0 system indicates that the total widths of decays to CPCP-even and CPCP-odd final states should be the same to within about a percent. The known contributions to the width difference from hadronic D0D^0 decays are discussed, and it is shown that an apparent excess of quasi-CPCP-even modes is balanced, within current uncertainty, by interference effects in quasi-flavour-specific decays. Decay modes which may significantly affect the picture with improved measurements are considered.Comment: 17 pages including 3 tables. v2: Updated with published version including new comments in summar

    A Green's function approach to the natural vibration of thin spherical shell segments - A numerical method Final report

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    Green function approach to natural vibration of thin spherical shell segment

    Maser radiometer for cosmic background radiation anisotropy measurements

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    A maser amplifier was incorporated into a low noise radiometer designed to measure large-scale anisotropy in the 3 deg K microwave background radiation. To minimize emission by atmospheric water vapor and oxygen, the radiometer is flown in a small balloon to an altitude to 25 km. Three successful flights were made - two from Palestine, Texas and one from Sao Jose dos Campos, Brazil. Good sky coverage is important to the experiment. Data from the northern hemisphere flights has been edited and calibrated

    Energy absorption by "sparse" systems: beyond linear response theory

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    The analysis of the response to driving in the case of weakly chaotic or weakly interacting systems should go beyond linear response theory. Due to the "sparsity" of the perturbation matrix, a resistor network picture of transitions between energy levels is essential. The Kubo formula is modified, replacing the "algebraic" average over the squared matrix elements by a "resistor network" average. Consequently the response becomes semi-linear rather than linear. Some novel results have been obtained in the context of two prototype problems: the heating rate of particles in Billiards with vibrating walls; and the Ohmic Joule conductance of mesoscopic rings driven by electromotive force. Respectively, the obtained results are contrasted with the "Wall formula" and the "Drude formula".Comment: 8 pages, 7 figures, short pedagogical review. Proceedings of FQMT conference (Prague, 2011). Ref correcte

    Invaded cluster algorithm for equilibrium critical points

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    A new cluster algorithm based on invasion percolation is described. The algorithm samples the critical point of a spin system without a priori knowledge of the critical temperature and provides an efficient way to determine the critical temperature and other observables in the critical region. The method is illustrated for the two- and three-dimensional Ising models. The algorithm equilibrates spin configurations much faster than the closely related Swendsen-Wang algorithm.Comment: 13 pages RevTex and 4 Postscript figures. Submitted to Phys. Rev. Lett. Replacement corrects problem in printing figure

    Crystallization and preliminary crystallographic analysis of the DNA gyrase B protein from B-stearothermophilus

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    DNA gyrase B (GyrB) from B. stearothermophilus has been crystallized in the presence of the non-hydrolyzable ATP analogue, 5'-adenylpl-beta-gamma-imidodiphosphate (ADPNP), by the dialysis method. A complete native data set to 3.7 Angstrom has been collected from crystals which belonged to the cubic space group I23 with unit-cell dimension a = 250.6 Angstrom. Self-rotation function analysis indicates the position of a molecular twofold axis. Low-resolution data sets of a thimerosal and a selenomethionine derivative have also been analysed. The heavy-atom positions are consistent with one dimer in the asymmetric unit
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