5,636 research outputs found
Exotic tensor gauge theory and duality
Gauge fields in exotic representations of the Lorentz group in D dimensions -
i.e. ones which are tensors of mixed symmetry corresponding to Young tableaux
with arbitrary numbers of rows and columns - naturally arise through massive
string modes and in dualising gravity and other theories in higher dimensions.
We generalise the formalism of differential forms to allow the discussion of
arbitrary gauge fields. We present the gauge symmetries, field strengths, field
equations and actions for the free theory, and construct the various dual
theories. In particular, we discuss linearised gravity in arbitrary dimensions,
and its two dual forms.Comment: 28 pages, LaTeX, references added, minor change
How good are MatLab, Octave and Scilab for Computational Modelling?
In this article we test the accuracy of three platforms used in computational
modelling: MatLab, Octave and Scilab, running on i386 architecture and three
operating systems (Windows, Ubuntu and Mac OS). We submitted them to numerical
tests using standard data sets and using the functions provided by each
platform. A Monte Carlo study was conducted in some of the datasets in order to
verify the stability of the results with respect to small departures from the
original input. We propose a set of operations which include the computation of
matrix determinants and eigenvalues, whose results are known. We also used data
provided by NIST (National Institute of Standards and Technology), a protocol
which includes the computation of basic univariate statistics (mean, standard
deviation and first-lag correlation), linear regression and extremes of
probability distributions. The assessment was made comparing the results
computed by the platforms with certified values, that is, known results,
computing the number of correct significant digits.Comment: Accepted for publication in the Computational and Applied Mathematics
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Invariant approach to CP in family symmetry models
We propose the use of basis invariants, valid for any choice of CP
transformation, as a powerful approach to studying specific models of CP
violation in the presence of discrete family symmetries. We illustrate the
virtues of this approach for examples based on and family
symmetries. For , we show how to elegantly obtain several known results in
the literature. In we use the invariant approach to identify how
explicit (rather than spontaneous) CP violation arises, which is geometrical in
nature, i.e. persisting for arbitrary couplings in the Lagrangian.Comment: 4 pages plus references. v2: to be published in PR
Invariant approach to CP in unbroken
The invariant approach is a powerful method for studying CP violation for
specific Lagrangians. The method is particularly useful for dealing with
discrete family symmetries. We focus on the CP properties of unbroken
invariant Lagrangians with Yukawa-like terms, which proves to be a
rich framework, with distinct aspects of CP, making it an ideal group to
investigate with the invariant approach. We classify Lagrangians depending on
the number of fields transforming as irreducible triplet representations of
. For each case, we construct CP-odd weak basis invariants and use
them to discuss the respective CP properties. We find that CP violation is
sensitive to the number and type of representations.Comment: 24 pages, 1 figure. v2: to be published in NP
Preparo e uso de soluções salinas saturadas para a caracterização fisiológica de sementes florestais.
bitstream/CNPF-2009-09/41217/1/circ-tec125.pd
Aspectos de dormência em sementes de espécies arbóreas.
bitstream/item/41994/1/CT0055.pd
Causal Structure and Birefringence in Nonlinear Electrodynamics
We investigate the causal structure of general nonlinear electrodynamics and
determine which Lagrangians generate an effective metric conformal to
Minkowski. We also proof that there is only one analytic nonlinear
electrodynamics presenting no birefringence.Comment: 11 pages, no figure
Cultivar de Arroz de Terras Altas BRSGO Serra Dourada: Desempenho Produtivo em Roraima.
bitstream/item/135279/1/COT-175-N77.pd
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