7,687 research outputs found

    Quantum quench dynamics of the Coulomb Luttinger model

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    We study the non-equilibrium dynamics of the Luttinger model after suddenly turning on and off the bare Coulomb interaction between the fermions. We analyze several correlation functions such as the one particle density matrix and vertex correlations, its finite time dynamics and the stationary state limit. Correlations exhibit a non-linear light cone effect: the spreading of the initial signal accelerates as a consequence of the quantum nature of the excitations, whose peculiar dispersion of plasmonic type in 1D gives rise to a logarithmic divergence in the group velocity at q=0q=0. In addition we show that both the static and dynamic stationary state correlations can be reproduced with a simple generalised Gibbs ensemble despite the long-range character of the interactions which precludes the application of the Lieb-Robinson bounds. We propose a suitable experimental setup in which these effect can be observed based on ultracold ions loaded on linear traps.Comment: 13 pages, 7 figure

    Equations of Motion for the Out-of-Equilibrium Dynamics of Isolated Quantum Systems from the Projection Operator Technique

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    We present a rigorous framework to obtain evolution equations for the momentum distribution and higher order correlation functions in weakly interacting systems based on the Projection Operator Technique. These equations can be numerically solved in an efficient way. We compare the solution of the equations with known results for 1D models and find an excellent agreement.Comment: 6 pages, 1 figure, added brief discussion about the validity of the approximation

    Thioxoethenylidene (CCS) as a bridging ligand

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    The reaction of [Mo(≡CBr)(CO)2(Tp*)] (Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate) with [Fe2(ÎŒ-SLi)2(CO)6] affords, inter alia, the unsymmetrical binuclear thioxoethenylidene complex [Mo2(ÎŒ,σ(C):η2(Câ€ČS)-CCS)(CO)4(Tp*)2], which may be more directly obtained from [Mo(≡CBr)(CO)2(Tp*)] and Li2S. The reaction presumably proceeds via the intermediacy of the bis(alkylidynyl)thioether complex S{C≡Mo(CO)2(Tp*)}2, which was, however, not directly observed but explored computationally and found to lie 78.6 kJ mol–1 higher in energy than the final thioxoethenylidene product. Computational interrogation of the molecules [M2(ÎŒ-C2S)(CO)2(Tp*)2] (M = Mo, W, Re, Os) reveals three plausible coordination modes for a thioxoethenylidene bridge which involve a progressive strengthening of the C–C bond and weakening of the M–C and M–S bonds, as might be expected from simple effective atomic number considerations.This work was supported by the Australian Research Council (DP130102598 and DP110101611)

    Cerium-Doped Fused-Silica Fibers as Wavelength Shifters

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    We have evaluated the performance of a Ce-doped fused-silica fiber as wavelength shifter coupled to a CeF3_{3} crystal using electron beams at CERN. The pulse shape and collection efficiency were measured using irradiated (100 kGy) and un-irradiated fibers. In addition, we evaluated the light yield of various Ce-doped fibers and explored the possibility of using them in the future, including for precision timing applications in a high-luminosity collider environment.Comment: 11 pages, 7 figure

    Proposal for SPS beam time for the baby MIND and TASD neutrino detector prototypes

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    The design, construction and testing of neutrino detector prototypes at CERN are ongoing activities. This document reports on the design of solid state baby MIND and TASD detector prototypes and outlines requirements for a test beam at CERN to test these, tentatively planned on the H8 beamline in the North Area, which is equipped with a large aperture magnet. The current proposal is submitted to be considered in light of the recently approved projects related to neutrino activities with the SPS in the North Area in the medium term 2015-2020

    Emerging Non-Anomalous Baryonic Symmetries in the AdS_5/CFT_4 Correspondence

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    We study the breaking of baryonic symmetries in the AdS_5/CFT_4 correspondence for D3 branes at Calabi-Yau three-fold singularities. This leads, for particular VEVs, to the emergence of non-anomalous baryonic symmetries during the renormalization group flow. We claim that these VEVs correspond to critical values of the B-field moduli in the dual supergravity backgrounds. We study in detail the C^3/Z_3 orbifold, the cone over F_0 and the C^3/Z_5 orbifold. For the first two examples, we study the dual supergravity backgrounds that correspond to the breaking of the emerging baryonic symmetries and identify the expected Goldstone bosons and global strings in the infra-red. In doing so we confirm the claim that the emerging symmetries are indeed non-anomalous baryonic symmetries.Comment: 65 pages, 15 figures;v2: minor changes, published versio

    Performance of a Tungsten-Cerium Fluoride Sampling Calorimeter in High-Energy Electron Beam Tests

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    A prototype for a sampling calorimeter made out of cerium fluoride crystals interleaved with tungsten plates, and read out by wavelength-shifting fibres, has been exposed to beams of electrons with energies between 20 and 150 GeV, produced by the CERN Super Proton Synchrotron accelerator complex. The performance of the prototype is presented and compared to that of a Geant4 simulation of the apparatus. Particular emphasis is given to the response uniformity across the channel front face, and to the prototype's energy resolution.Comment: 6 pages, 6 figures, Submitted to NIM
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