3,120 research outputs found

    A visualization of the damage in Lead Tungstate calorimeter crystals after exposure to high-energy hadrons

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    The anticipated performance of calorimeter crystals in the environment expected after the planned High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN has to be well understood, before informed decisions can be made on the need for detector upgrades. Throughout the years of running at the HL-LHC, the detectors will be exposed to considerable fluences of fast hadrons, that have been shown to cause cumulative transparency losses in Lead Tungstate scintillating crystals. In this study, we present direct evidence of the main underlying damage mechanism. Results are shown from a test that yields a direct insight into the nature of the hadron-specific damage in Lead Tungstate calorimeter crystals exposed to 24 GeV/c protons.Comment: 8 pages, 6 figure

    Kink fluctuation asymptotics and zero modes

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    In this paper we propose a refinement of the heat kernel/zeta function treatment of kink quantum fluctuations in scalar field theory, further analyzing the existence and implications of a zero energy fluctuation mode. Improved understanding of the interplay between zero modes and the kink heat kernel expansion delivers asymptotic estimations of one-loop kink mass shifts with remarkably higher precision than previously obtained by means of the standard Gilkey-DeWitt heat kernel expansion.Comment: 21 pages, 8 figures, to be published in The European Physical Journal

    Advanced content-based semantic scene analysis and information retrieval: the SCHEMA project

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    The aim of the SCHEMA Network of Excellence is to bring together a critical mass of universities, research centers, industrial partners and end users, in order to design a reference system for content-based semantic scene analysis, interpretation and understanding. Relevant research areas include: content-based multimedia analysis and automatic annotation of semantic multimedia content, combined textual and multimedia information retrieval, semantic -web, MPEG-7 and MPEG-21 standards, user interfaces and human factors. In this paper, recent advances in content-based analysis, indexing and retrieval of digital media within the SCHEMA Network are presented. These advances will be integrated in the SCHEMA module-based, expandable reference system

    Femtosecond multichannel photodissociation dynamics of CH3I from the A band by velocity map imaging

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    4 pages, 3 figures, 1 table.The reaction times of several well-defined channels of the C–I bond rupture of methyl iodide from the A band, which involves nonadiabatic dynamics yielding ground state I(2P3/2) and spin-orbit excited I*(2P1/2) and ground and vibrationally excited CH3 fragments, have been measured by a combination of a femtosecond laser pump-probe scheme and velocity map imaging techniques using resonant detection of ground state CH3 fragments. The reaction times found for the different channels studied are directly related with the nonadiabatic nature of this multidimensional photodissociation reaction.Two of the authors (J. G. I. and J. D.) gratefully acknowledge financial support from the FPI program and the CSIC-Unidades Asociadas program, respectively, of the Spanish Ministry of Education and Science (MEC). This work has been financed by the Spanish MEC through Grant No. CTQ2005-08493- C02-01.Peer reviewe

    On domain walls in a Ginzburg-Landau non-linear S^2-sigma model

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    The domain wall solutions of a Ginzburg-Landau non-linear S2S^2-sigma hybrid model are unveiled. There are three types of basic topological walls and two types of degenerate families of composite - one topological, the other non-topological- walls. The domain wall solutions are identified as the finite action trajectories (in infinite time) of a related mechanical system that is Hamilton-Jacobi separable in sphero-conical coordinates. The physical and mathematical features of these domain walls are thoroughly discussed.Comment: 26 pages, 18 figure

    Large deviations principle for the cubic NLS equation

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    In this paper, we present a probabilistic study of rare phenomena of the cubic nonlinear Schrodinger equation on the torus in a weakly nonlinear setting. This equation has been used as a model to numerically study the formation of rogue waves in deep sea. Our results are twofold: first, we introduce a notion of criticality and prove a Large Deviations Principle (LDP) for the subcritical and critical cases. Second, we study the most likely initial conditions that lead to the formation of a rogue wave, from a theoretical and numerical point of view. Finally, we propose several open questions for future research

    Supergeometry of Three Dimensional Black Holes

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    We show how the supersymmetric properties of three dimensional black holes can be obtained algebraically. The black hole solutions are constructed as quotients of the supergroup OSp(1∣ 2;R)OSp(1|\,2;R) by a discrete subgroup of its isometry supergroup. The generators of the action of the isometry supergroup which commute with these identifications are found. These yield the supersymmetries for the black hole as found in recent studies as well as the usual geometric isometries. It is also shown that in the limit of vanishing cosmological constant, the black hole vacuum becomes a null orbifold, a solution previously discussed in the context of string theory.Comment: 12 pages, harvmac, discussion of rotating black hole added, some minor corrections, reference adde

    Private concession contracts for toll roads in Spain: analysis and recommendations.

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    Spain has a long history of using the private sector to help build and operate public infrastructure, particularly roads. This article presents new data about toll motorways. The authors found that contracts in Spain are characterized by significant traffic overestimations and frequent renegotiations, which can lead to toll modifications or longer contracts. They suggest reasons for this and some solutions—both of which have significance for other countries

    Killing spinors, the adS black hole and I(ISO(2,1)) gravity

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    We construct a supersymmetric extension of the I(ISO(2,1))I\big(ISO(2,1)\big) Chern-Simons gravity and show that certain particle-like solutions and the adS black-hole solution of this theory are supersymmetric.Comment: 12 pages, uses phyzz
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