524 research outputs found

    Quantum mechanics with time-dependent parameters

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    Smooth composite bundles provide the adequate geometric description of classical mechanics with time-dependent parameters. We show that the Berry's phase phenomenon is described in terms of connections on composite Hilbert space bundles.Comment: 7 pages, LaTe


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    SUMMARY treatment. A simple procedure is described for the purification, from rat None of a variety of other monophosphate and diphosphate liver, of a diphosphatase activity which cleaves both fructose esters tested as substrates was cleaved by the purified enzyme diphosphate and sedoheptulose diphosphate to fructose 6-phos- at significant rates. These results suggest an absolute require- phate and sedoheptulose 7-phosphate, respectively. ment for the presence of two phosphate groups and also for the Evidence that a single enzyme is responsible for both reactions configuration found in FDP and SDP. n-Bibulose 1,5-diphos- is derived from the results of the purification steps, from kinetic phate differs in the configuration at C-3 and is not attacked. measurements, and from other properties. The enzyme has no With respect to the physiological role of the diphosphatase, activity with a variety of monophosphate esters and other di- although it has been generally recognized that fructose diphos- phosphate esters. phatase may represent a key enzyme in the synthesis of glycogen Both activities are present in the liver of all mammalian species from 3 carbon fragments, no direct evidence for a role of sedo- studied. heptulose diphosphatase has yet been obtained. REFERENCES Three possibilities may be considered with respect to the physiological significance of the latter activity. (a) It may be 1. GOMORI, G., J

    Resistive plate chambers for time-of-flight measurements

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    The applications of Resistive Plate Chambers (RPCs) have recently been extended by the development of counters with time resolution below 100 ps sigma for minimum ionising particles. Applications to HEP experiments have already taken place and many further applications are under study. In this work we address the operating principles of such counters along with some present challenges, with emphasis on counter aging.Comment: Presented at "PSD6 - 6th International Conference on Position Sensitive Detectors", 9-13 September 2002, Leicester, UK. Submitted to Nuclear Instruments and Methods

    Geometric quantization of mechanical systems with time-dependent parameters

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    Quantum systems with adiabatic classical parameters are widely studied, e.g., in the modern holonomic quantum computation. We here provide complete geometric quantization of a Hamiltonian system with time-dependent parameters, without the adiabatic assumption. A Hamiltonian of such a system is affine in the temporal derivative of parameter functions. This leads to the geometric Berry factor phenomena.Comment: 20 page

    Inclusive pion and η production in p+Nb collisions at 3.5 GeV beam energy

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    Data on inclusive pion and η production measured with the dielectron spectrometer HADES in the reaction p+93Nb at a kinetic beam energy of 3.5 GeV are presented. Our results, obtained with the photon-conversion method, supplement the rather sparse information on neutral-meson production in proton-nucleus reactions existing for this bombarding energy regime. The reconstructed e+e−e+e− transverse-momentum and rapidity distributions are confronted with transport-model calculations, which account fairly well for both π0 and η production.Peer Reviewe

    An upper limit on hypertriton production in collisions of Ar(1.76 A GeV) + KCl

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    A high-statistic data sample of Ar(1.76 AGeV)+KCl events recorded with HADES is used to search for a hypertriton signal. An upper production limit per centrality-triggered event of 1.041.04 x 10−310^{-3} on the 3σ3\sigma level is derived. Comparing this value with the number of successfully reconstructed Λ\Lambda hyperons allows to determine an upper limit on the ratio NΛ3H/NΛN_{_{\Lambda}^3H}/N_{\Lambda}, which is confronted with statistical and coalescence-type model calculations.Peer Reviewe