15,512 research outputs found

    One-loop N-point equivalence among negative-dimensional, Mellin-Barnes and Feynman parametrization approaches to Feynman integrals

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    We show that at one-loop order, negative-dimensional, Mellin-Barnes' (MB) and Feynman parametrization (FP) approaches to Feynman loop integrals calculations are equivalent. Starting with a generating functional, for two and then for NN-point scalar integrals we show how to reobtain MB results, using negative-dimensional and FP techniques. The NN-point result is valid for different masses, arbitrary exponents of propagators and dimension.Comment: 11 pages, LaTeX. To be published in J.Phys.

    General massive one-loop off-shell three-point functions

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    In this work we compute the most general massive one-loop off-shell three-point vertex in D-dimensions, where the masses, external momenta, and exponents of propagators are arbitrary. This follows our previous paper in which we have calculated several new hypergeometric series representations for massless and massive (with equal masses) scalar one-loop three-point functions, in the negative dimensional approach.Comment: 16 pages, 2 figures, 4 table

    Cosmic strings in axionic-dilatonic gravity

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    We first consider local cosmic strings in dilaton-axion gravity and show that they are singular solutions. Then we take a supermassive Higgs limit and present expressions for the fields at far distances from the core by applying a Pecci-Quinn and a duality transformation to the dilatonic Melvin's magnetic universe.Comment: Latex file. 16 page

    Exploiting Term Hiding to Reduce Run-time Checking Overhead

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    One of the most attractive features of untyped languages is the flexibility in term creation and manipulation. However, with such power comes the responsibility of ensuring the correctness of these operations. A solution is adding run-time checks to the program via assertions, but this can introduce overheads that are in many cases impractical. While static analysis can greatly reduce such overheads, the gains depend strongly on the quality of the information inferred. Reusable libraries, i.e., library modules that are pre-compiled independently of the client, pose special challenges in this context. We propose a technique which takes advantage of module systems which can hide a selected set of functor symbols to significantly enrich the shape information that can be inferred for reusable libraries, as well as an improved run-time checking approach that leverages the proposed mechanisms to achieve large reductions in overhead, closer to those of static languages, even in the reusable-library context. While the approach is general and system-independent, we present it for concreteness in the context of the Ciao assertion language and combined static/dynamic checking framework. Our method maintains the full expressiveness of the assertion language in this context. In contrast to other approaches it does not introduce the need to switch the language to a (static) type system, which is known to change the semantics in languages like Prolog. We also study the approach experimentally and evaluate the overhead reduction achieved in the run-time checks.Comment: 26 pages, 10 figures, 2 tables; an extension of the paper version accepted to PADL'18 (includes proofs, extra figures and examples omitted due to space reasons

    Exactly solvable models for triatomic-molecular Bose-Einstein Condensates

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    We construct a family of triatomic models for heteronuclear and homonuclear molecular Bose-Einstein condensates. We show that these new generalized models are exactly solvable through the algebraic Bethe ansatz method and derive their corresponding Bethe ansatz equations and energies.Comment: 11 page

    Natural Diagonal Riemannian Almost Product and Para-Hermitian Cotangent Bundles

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    We obtain the natural diagonal almost product and locally product structures on the total space of the cotangent bundle of a Riemannian manifold. We find the Riemannian almost product (locally product) and the (almost) para-Hermitian cotangent bundles of natural diagonal lift type. We prove the characterization theorem for the natural diagonal (almost) para-K\"ahlerian structures on the total spaces of the cotangent bundle.Comment: 10 pages, will appear in Czechoslovak Mathematical Journa

    Effects of hCG on progesterone concentrations and fertility in cyclic, lactating Alpine goats.

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    The objective of this study was to evaluate the effect of hCG administration on plasma progesterone concentrations in lactating Alpine goats during the natural breeding season. After detection of estrus, 124 does were randomly assigned to one of two treatments (T1 and T2). In T1 (n = 60) and T2 (n = 64), the animals received 1 ml of saline solution or 250 IU of hCG i.m., respectively, 5 days after the first detection of estrus and breeding. Plasma progesterone concentration (ng/mL) was determined from blood sampled (T1 = 12 and T2 = 13) on Days 0 (day of estrus), 5, 7, 13, 17, 21, 28 and 45 after breeding. Two control goats with short cycles and two nymphomaniac goats (one per treatment) were detected. Plasma progesterone concentration (mean ± SEM) for T1 and T2 females differed on Days 13, 17 (P 0.05) between T1 (78.3%) and T2 (84.4%) does. The hCG administration 5 days after breeding increased plasma progesterone concentrations on Days 13 to 21 but did not increase pregnancy rate

    Impurity Effects on Superconductivity on Surfaces of Topological Insulators

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    A two-dimensional superconductor (SC) on surfaces of topological insulators (TIs) is a mixture of s-wave and helical p-wave components when induced by s-wave interactions, since spin and momentum are correlated. On the basis of the Abrikosov-Gor'kov theory, we reveal that unconventional SCs on the surfaces of TIs are stable against time-reversal symmetric (TRS) impurities within a region of small impurity concentration. Moreover, we analyze the stability of the SC on the surfaces of TIs against impurities beyond the perturbation theory by solving the real-space Bogoliubov-de Gennes equation for an effective tight-binding model of a TI. We find that the SC is stable against strong TRS impurities. The behaviors of bound states around an impurity suggest that the SC on the surfaces of TIs is not a topological SC.Comment: 17 pages, 14 figures, to appear in J. Phys. Soc. Jp

    Plasmons in layered structures including graphene

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    We investigate the optical properties of layered structures with graphene at the interface for arbitrary linear polarization at finite temperature including full retardation by working in the Weyl gauge. As a special case, we obtain the full response and the related dielectric function of a layered structure with two interfaces. We apply our results to discuss the longitudinal plasmon spectrum of several single and double layer devices such as systems with finite and zero electronic densities. We further show that a nonhomogeneous dielectric background can shift the relative weight of the in-phase and out-of-phase mode and discuss how the plasmonic mode of the upper layer can be tuned into an acoustic mode with specific sound velocity.Comment: 18 pages, 6 figure
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