74,406 research outputs found

    Renormalization of Fermion-Flavour Mixing

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    We report on an explicit on-shell framework to renormalize the fermion-flavour mixing matrices in the Standard Model and its extensions, at one-loop level. It is based on a novel procedure to separate the external-leg mixing corrections into gauge-independent self-mass and gauge-dependent wave-function renormalization contributions.Comment: to appear in Proceedings of Lepton-Photon 2009, Hamburg, German

    Theory of Change As A Tool For Strategic Planning

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    The purpose of this paper is to introduce the use of the Theory of Change approach for planning community-based initiatives. Through lessons learned from a case study of how TOC was applied during the planning phase of The Wallace Foundation Parents and Communities for Kids (PACK) initiative, the utility of this technique and the challenges involved in employing it are illustrated. The case study was designed to highlight lessons that will be of most interest to program planners, evaluators, and funders who are interested in applying this method to their work

    The Gardner Category and Non-local Conservation Laws for N=1 Super KdV

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    The non-local conserved quantities of N=1 Super KdV are obtained using a complete algebraic framework where the Gardner category is introduced. A fermionic substitution semigroup and the resulting Gardner category are defined and several propositions concerning their algebraic structure are proven. This algebraic framework allows to define general transformations between different nonlinear SUSY differential equations. We then introduce a SUSY ring extension to deal with the non-local conserved quantities of SKdV. The algebraic version of the non-local conserved quantities is solved in terms of the exponential function applied to the D−1D^{-1} of the local conserved quantities of SKdV. Finally the same formulas are shown to work for rapidly decreasing superfields.Comment: 17 page

    Scenario Modeling for the Management of International Bond Portfolios

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    We address the problem of portfolio management in the international bond markets. Interest rate risk in the local market, exchange rate volatility across markets, and decisions for hedging currency risk are integral parts of this problem. The paper develops a stochastic programming optimization model for integrating these decisions in a common framework. Monte Carlo simulation procedures, calibrated using historical observations of volatility and correlation data, generate jointly scenarios of interest and exchange rates. The decision maker's risk tolerance is incorporated through a utility function, and additional views on market outlook can also be incorporated in the form of user specified scenarios. The model prescribes optimal asset allocation among the different markets and determines bond-picking decisions and appropriate hedging ratios. Therefore several interrelated decisions are cast in a common framework, while in the past these issues were addressed separately. Empirical results illustrate the efficacy of the simulation models in capturing the uncertainties of the Salomon Brothers international bond market index.

    Singular hermitian metrics on vector bundles

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    We introduce a notion of singular hermitian metrics (s.h.m.) for holomorphic vector bundles and define positivity in view of L2L^2-estimates. Associated with a suitably positive s.h.m. there is a (coherent) sheaf 0-th kernel of a certain d′′d''-complex. We prove a vanishing theorem for the cohomology of this sheaf. All this generalizes to the case of higher rank known results of Nadel for the case of line bundles. We introduce a new semi-positivity notion, tt-nefness, for vector bundles, establish some of its basic properties and prove that on curves it coincides with ordinary nefness. We particularize the results on s.h.m. to the case of vector bundles of the form E=F⊗LE=F \otimes L, where FF is a tt-nef vector bundle and LL is a positive (in the sense of currents) line bundle. As applications we generalize to the higher rank case 1) Kawamata-Viehweg Vanishing Theorem, 2) the effective results concerning the global generation of jets for the adjoint to powers of ample line bundles, and 3) Matsusaka Big Theorem made effective.Comment: LaTex (article) 25 pages; revised: minor changes; to appear in Crelle's J; dedicated to Michael Schneide
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