1,271 research outputs found

    Spontaneous Symmetry Breaking and the Renormalization of the Chern-Simons Term

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    We calculate the one-loop perturbative correction to the coefficient of the \cs term in non-abelian gauge theory in the presence of Higgs fields, with a variety of symmetry-breaking structures. In the case of a residual U(1)U(1) symmetry, radiative corrections do not change the coefficient of the \cs term. In the case of an unbroken non-abelian subgroup, the coefficient of the relevant \cs term (suitably normalized) attains an integral correction, as required for consistency of the quantum theory. Interestingly, this coefficient arises purely from the unbroken non-abelian sector in question; the orthogonal sector makes no contribution. This implies that the coefficient of the \cs term is a discontinuous function over the phase diagram of the theory.Comment: Version to be published in Phys Lett B., minor additional change

    Perfect Teleportation, Quantum state sharing and Superdense Coding through a Genuinely Entangled Five-qubit State

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    We investigate the usefulness of a recently introduced five qubit state by Brown \it et al. \normalfont \cite{Brown} for quantum teleportation, quantum state sharing and superdense coding. It is shown that this five-qubit state can be utilized for perfect teleportation of arbitrary single and two qubit systems. We devise various schemes for quantum state sharing of an arbitrary single and two particle state via cooperative teleportation. We later show that this state can be used for superdense coding as well. It is found that five classical bits can be sent by sending only three quantum bits.Comment: 8 Pages, added sections on state sharin

    Provenance Views for Module Privacy

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    Scientific workflow systems increasingly store provenance information about the module executions used to produce a data item, as well as the parameter settings and intermediate data items passed between module executions. However, authors/owners of workflows may wish to keep some of this information confidential. In particular, a module may be proprietary, and users should not be able to infer its behavior by seeing mappings between all data inputs and outputs. The problem we address in this paper is the following: Given a workflow, abstractly modeled by a relation R, a privacy requirement \Gamma and costs associated with data. The owner of the workflow decides which data (attributes) to hide, and provides the user with a view R' which is the projection of R over attributes which have not been hidden. The goal is to minimize the cost of hidden data while guaranteeing that individual modules are \Gamma -private. We call this the "secureview" problem. We formally define the problem, study its complexity, and offer algorithmic solutions

    First-principles calculation of phase equilibrium of V-Nb, V-Ta, and Nb-Ta alloys

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    In this paper, we report the calculated phase diagrams of V-Nb, V-Ta, and Nb-Ta alloys computed by combining the total energies of 40–50 configurations for each system (obtained using density functional theory) with the cluster expansion and Monte Carlo techniques. For V-Nb alloys, the phase diagram computed with conventional cluster expansion shows a miscibility gap with consolute temperature T_c=1250 K. Including the constituent strain to the cluster expansion Hamiltonian does not alter the consolute temperature significantly, although it appears to influence the solubility of V- and Nb-rich alloys. The phonon contribution to the free energy lowers T_c to 950 K (about 25%). Our calculations thus predicts an appreciable miscibility gap for V-Nb alloys. For bcc V-Ta alloy, this calculation predicts a miscibility gap with T_c=1100 K. For this alloy, both the constituent strain and phonon contributions are found to be significant. The constituent strain increases the miscibility gap while the phonon entropy counteracts the effect of the constituent strain. In V-Ta alloys, an ordering transition occurs at 1583 K from bcc solid solution phase to the V_(2)Ta Laves phase due to the dominant chemical interaction associated with the relatively large electronegativity difference. Since the current cluster expansion ignores the V_(2)Ta phase, the associated chemical interaction appears to manifest in making the solid solution phase remain stable down to 1100 K. For the size-matched Nb-Ta alloys, our calculation predicts complete miscibility in agreement with experiment

    Study on flow characteristics of primary blast furnace slag

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    The primary slag generated in the cohesive zone of the blast furnace determines the fuel rate as well as the quality of the hot metal in terms of its silicon content. This is because in the cohesive zone the softened slag chokes the path of gas flow, interfering with the permeability of the bed. Therefore, the cohesive zone which starts with the softening of the primary slag and ends with its flow should be formed lower down the furnace and should be a narrow one with a minimum difference between the flow temperature and the softening temperature. In the present work pellets with C/S ratio ranging from 1.8 to 2.4 with a fixed MgO content of 10% are reduced in the laboratory at different temperature ranging from 1200 C – 1400 C. Synthetic slags prepared in the laboratory in line with the comparison of reduced pellets are analyzed for its flow characteristics using the heating microscope (German Standard 51730). It is observed that under the composition examined, the pellet with C/S ratio 2.0 rendered the best result with the highest softening temperature and lowest flow temperature

    A novel conductometric titration approach for rapid determination of boron

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    21-30In laboratories dealing with radioactive samples it is important to minimize both the sample size and also the associated waste generated in an analysis. To meet this objective a rapid conductometric titration technique is developed to determine boron in the moderators of Pressurized Heavy Water Reactors (PHWR’s). Using this novel PC interfaced titration facility a minimum tenfold reduction in sample size is achieved compared to conventional conductometric titration. Determination of boron is based on the conversion of extremely weak boric acid to better conducting boron mannitol complex and titrating the complex against NaOH. Various parameters affecting the analysis, when moving from large to small sample size, are analyzed and optimized. The technique is primarily proposed for the assay of boron (≥0.5 ppm) during reactor startup. Each analysis requires less than 10 min. The detection limit is 0.5 ppm and the precision obtained at this level is 4.6% RSD. The technique is a good alternative to less sensitive carminic acid based spectrophotometric method
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