11,810 research outputs found

    Specific heat amplitude ratios for anisotropic Lifshitz critical behaviors

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    We determine the specific heat amplitude ratio near a mm-axial Lifshitz point and show its universal character. Using a recent renormalization group picture along with new field-theoretical ϵL\epsilon_{L}-expansion techniques, we established this amplitude ratio at one-loop order. We estimate the numerical value of this amplitude ratio for m=1m=1 and d=3d=3. The result is in very good agreement with its experimental measurement on the magnetic material MnPMnP. It is shown that in the limit m→0m \to 0 it trivially reduces to the Ising-like amplitude ratio.Comment: 8 pages, RevTex, accepted as a Brief Report in Physical Review

    Topological Dilatonic Supergravity Theories

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    We present a central extension of the (m,n)(m,n) super-Poincar\'e algebra in two dimensions. Besides the usual Poincar\'e generators and the (m,n)(m,n) supersymmetry generators we have (m,n)(m,n) Grassmann generators, a bosonic internal symmetry generator and a central charge. We then build up the topological gauge theory associated to this algebra. We can solve the classical field equations for the fields which do not belong to the supergravity multiplet and to a Lagrange multiplier multiplet. The resulting topological supergravity theory turns out to be non-local in the fermionic sector.Comment: 11 pages, plain TeX, IFUSP-P/112

    A new picture of the Lifshitz critical behavior

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    New field theoretic renormalization group methods are developed to describe in a unified fashion the critical exponents of an m-fold Lifshitz point at the two-loop order in the anisotropic (m not equal to d) and isotropic (m=d close to 8) situations. The general theory is illustrated for the N-vector phi^4 model describing a d-dimensional system. A new regularization and renormalization procedure is presented for both types of Lifshitz behavior. The anisotropic cases are formulated with two independent renormalization group transformations. The description of the isotropic behavior requires only one type of renormalization group transformation. We point out the conceptual advantages implicit in this picture and show how this framework is related to other previous renormalization group treatments for the Lifshitz problem. The Feynman diagrams of arbitrary loop-order can be performed analytically provided these integrals are considered to be homogeneous functions of the external momenta scales. The anisotropic universality class (N,d,m) reduces easily to the Ising-like (N,d) when m=0. We show that the isotropic universality class (N,m) when m is close to 8 cannot be obtained from the anisotropic one in the limit d --> m near 8. The exponents for the uniaxial case d=3, N=m=1 are in good agreement with recent Monte Carlo simulations for the ANNNI model.Comment: 48 pages, no figures, two typos fixe

    A Nuclear Physics Program at the ATLAS Experiment at the CERN Large Hadron Collider

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    The ATLAS collaboration has significant interest in the physics of ultra-relativistic heavy ion collisions. We submitted a Letter of Intent to the United States Department of Energy in March 2002. The following document is a slightly modified version of that LOI. More details are available at: http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/SM/ionsComment: Letter of Intent submitted to the United States Department of Energy Nuclear Physics Division in March 2002 (revised version

    Gestão do conhecimento científico: proposta de um modelo conceitual com base em processo de comunicação científica.

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    A gestão do conhecimento tem se desenvolvido no ambiente das organizações empresariais e tem suas pesquisas e aplicações voltadas para a perspectiva do conhecimento organizacional. No entanto, existem outros contextos nos quais a gestão do conhecimento pode ser estudada, como, por exemplo, o contexto acadêmico, voltado para a perspectiva do conhecimento científico. Independentemente do contexto em que se inserem, os processos de comunicação constituem uma questão fundamental a ser levada em consideração em estudos sobre gestão do conhecimento
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