44,495 research outputs found
Revealing hidden symmetries and gauge invariance of the massive Carroll-Field-Jackiw model
In this paper we have analyzed the improved version of the Gauge Unfixing
(GU) formalism of the massive Carroll-Field-Jackiw model, which breaks both the
Lorentz and gauge invariances, to disclose hidden symmetries to obtain gauge
invariance, the key stone of the Standard Model. In this process, as usual, we
have converted this second-class system into a first-class one and we have
obtained two gauge invariant models. We have verified that the Poisson brackets
involving the gauge invariant variables, obtained through the GU formalism,
coincide with the Dirac brackets between the original second-class variables of
the phase space. Finally, we have obtained two gauge invariant Lagrangians
where one of them represents the Stueckelberg form.Comment: revised version. To appear in Europhysics Letter
Two photon decay of and at finite temperature and density
A comparative study of the anomalous decays , at
finite temperature and at finite density, is performed in the framework of the
three--flavor Nambu--Jona-Lasinio. The similarities and differences between
both scenarios are discussed. In both cases the lifetimes of these mesons
decrease significantly at the critical point, although this might not be
sufficient to observe enhancement of these decays in heavy-ion collisions.Comment: 5 pages, 1 figure. Talk given at Strange Quark Matter 2004, Cape
Town, South Africa, 15-20 September, 200
Leguminosas arbóreas e arbustivas de múltiplo uso em Presidente Médici, Rondônia.
Este trabalho teve como objetivo avaliar o desempenho agronômico de leguminosas com potencial de múltiplos usos para compor sistemas mais apropriados as condições de solo e clima locais, visando a manutenção da potencialidade produtiva das áreas. Foram avaliadas taxa de sobrevivência, diâmetro e altura de plantas, em Latossolo Amarelo no Município de Porto Velho-RO, destacando-se como mais promissoras A. angustissima, I.edulis, C. racemosa, A. samam e A. pavonina.bitstream/item/42536/1/Cot299-leguminosas.pd
HST Observations of the Central-Cusp Globular Cluster NGC 6752. The Effect of Binary Stars on the Luminosity Function in the Core
We consider the effect of binary stars on the main-sequence luminosity
functions observed in the core of globular clusters, with specific reference to
NGC 6752. We find that mass segregation results in an increased binary fraction
at fainter magnitudes along the main-sequence. If this effect is not taken into
account when analyzing luminosity functions, erroneous conclusions can be drawn
regarding the distribution of single stars, and the dynamical state of the
cluster. In the core of NGC 6752, our HST data reveal a flat luminosity
function, in agreement with previous results. However, when we correct for the
increasing binary fraction at faint magnitudes, the LF begins to fall
immediately below the turn-off. This effect appears to be confined to the inner
core radius of the cluster.Comment: 10 pages, 3 figures Accepted to ApJ Lett Vol 513 Number
Local Adaptive Receptive Field Self-Organizing Map for Image Segmentation
A new self-organizing map with variable topology is introduced for image segmentation. The proposed network, called Local Adaptive Receptive Field Self-Organizing Map (LARFSOM-RBF), is a two-stage network capable of both color and border segment images. The color segmentation stage is responsibility of LARFSOM which is characterized by adaptive number of nodes, fast convergence and variable topology. For border segmentation RBF nodes are included to determine the border pixels using previously learned information of LARFSOM. LARFSOM-RBF was tested to segment images with different degrees of complexity showing promising results
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