7,042 research outputs found
Improvement of the hot QCD pressure by the minimal sensitivity criterion
The principles of minimal sensitivity (PMS) criterion is applied to the
perturbative free energy density, or pressure, of hot QCD, which include the
and part of the terms. Applications are made
separately to the short- and long-distance parts of the pressure. Comparison
with the lattice results, at low temperatures, shows that the resultant ``
optimal'' approximants are substantially improved when compared to the
results. In particular, for the realistic case of three quark
flavors, the `` optimal'' approximants are comparable with the lattice results.Comment: 14 pages, 9 figures, LaTe
O mutualismo como forma de gestão de risco na agricultura.
A agricultura é, notadamente, uma atividade que apresenta grau elevado de risco. Fenômenos climáticos extremos, por exemplo, podem afetar, de forma negativa, a produtividade e a rentabilidade do setor. Para protegerem-se desse risco os produtores utilizam mecanismos que buscam mitigá-lo, dos quais o mutualismo é uma das formas mais antigas. Este artigo enfoca, de maneira analítica, as principais iniciativas dos produtores de criar, por meio de suas cooperativas, sociedades mútuas que os assegurem contra eventos aleatórios adversos
Broken-symmetry-adapted Green function theory of condensed matter systems:towards a vector spin-density-functional theory
The group theory framework developed by Fukutome for a systematic analysis of
the various broken symmetry types of Hartree-Fock solutions exhibiting spin
structures is here extended to the general many body context using spinor-Green
function formalism for describing magnetic systems. Consequences of this theory
are discussed for examining the magnetism of itinerant electrons in nanometric
systems of current interest as well as bulk systems where a vector spin-density
form is required, by specializing our work to spin-density-functional
formalism. We also formulate the linear response theory for such a system and
compare and contrast them with the recent results obtained for localized
electron systems. The various phenomenological treatments of itinerant magnetic
systems are here unified in this group-theoretical description.Comment: 17 page
Search for magnetic monopoles using proportional counters filled with helium gas
Slow magnetic monopoles in cosmic rays have been searched at sea level with the detector which consists of seven layers of proportional counters filled with a mixture of He + 20% CH4. The velocities and the energy losses of the incident particles are measured. The upper limit of flux for the monopoles in the velocity range of 1 x 0.001 Beta 4 x 0.001 is 2.78 x 10 to the minus 12th power square centimeters sr sec of 90% confidence level
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