1,249 research outputs found
Extension of the Nambu--Jona-Lasinio model at high densities and temperatures by using an implicit regularization scheme
Traditional cutoff regularization schemes of the Nambu--Jona-Lasinio model
limit the applicability of the model to energy-momentum scales much below the
value of the regularizing cutoff. In particular, the model cannot be used to
study quark matter with Fermi momenta larger than the cutoff. In the present
work an extension of the model to high temperatures and densities recently
proposed by Casalbuoni, Gatto, Nardulli, and Ruggieri is used in connection
with an implicit regularization scheme. This is done by making use of scaling
relations of the divergent one-loop integrals that relate these integrals at
different energy-momentum scales. Fixing the pion decay constant at the chiral
symmetry breaking scale in the vacuum, the scaling relations predict a running
coupling constant that decreases as the regularization scale increases,
implementing in a schematic way the property of asymptotic freedom of quantum
chromodynamics. If the regularization scale is allowed to increase with density
and temperature, the coupling will decrease with density and temperature,
extending in this way the applicability of the model to high densities and
temperatures. These results are obtained without specifying an explicit
regularization. As an illustration of the formalism, numerical results are
obtained for the finite density and finite temperature quark condensate, and to
the problem of color superconductivity at high quark densities and finite
temperature.Comment: 7 pages, 5 eps figures - in version 3, substantial changes in text,
results and conclusions unchanged. To be published in Phys. Rev.
Utilização de sensoriamento remoto hiperespectral na discriminação das rochas ácidas e básicas da formação Serra Geral na região vitivinícola Serra Gaúcha, Rio Grande do sul, Brasil.
O objetivo deste trabalho foi avaliar a possibilidade de distinguir as rochas ácidas e básicas da Formação Serra Geral, na região vitivinícola Serra Gaúcha no Estado do Rio Grande do Sul, por meio de técnicas de sensoriamento remoto hiperespectral orbital, buscando contribuir para caracterização de áreas de indicação geográfica vitivinícola
Transition from single-file to two-dimensional diffusion of interacting particles in a quasi-one-dimensional channel
Diffusive properties of a monodisperse system of interacting particles
confined to a \textit{quasi}-one-dimensional (Q1D) channel are studied using
molecular dynamics (MD) simulations. We calculate numerically the mean-squared
displacement (MSD) and investigate the influence of the width of the channel
(or the strength of the confinement potential) on diffusion in finite-size
channels of different shapes (i.e., straight and circular). The transition from
single-file diffusion (SFD) to the two-dimensional diffusion regime is
investigated. This transition (regarding the calculation of the scaling
exponent () of the MSD ) as a
function of the width of the channel, is shown to change depending on the
channel's confinement profile. In particular the transition can be either
smooth (i.e., for a parabolic confinement potential) or rather sharp/stepwise
(i.e., for a hard-wall potential), as distinct from infinite channels where
this transition is abrupt. This result can be explained by qualitatively
different distributions of the particle density for the different confinement
potentials.Comment: 13 pages, 11 figure
Elaboração de filmes finos comestíveis de amido adicionado de vitamina C e caratenóides na forma de polpa de acerola.
Título: caratenóides [i.e. carotenóides]
Avaliação de sobrevivência e desempenho de "SEEDLINGS" de Umbuzeiro ( Spondias tuberosa ) após dois períodos de incubação de substrato contendo farelo de mamona.
O umbuzeiro (Spondias tuberosa Arruda Câmara) é uma frutífera nativa da região Nordeste do Brasil, representando fonte de emprego e renda no período da safra, para as populações na área de ocorrência natural das plantas. Estudos indicam que o uso racional de farelo de mamona poderá disponibilizar às plantas quantidades suficiente de nutrientes, dispensando o uso complementar de fertilizante mineral, em especial os nitrogenados
Gamma-ray spectrometry for distinguishing acid and basic rocks of the serra geral formation, in the serra gaúcha wine region, Brazil.
The gamma-ray spectrometric research has allowed for observation of the distribution of radioactive elements such as K, U and Th for recognizing the radioactive signatures of different rock types. The objective of this study was to evaluate the possibility to distinguish between acid and basic rocks of the Serra Geral Formation, in the Serra Gaúcha wine region in the state of Rio Grande do Sul (Brazil) through gamma-ray spectrometry techniques. This study contributed to geologically... Keywords: geophysical method, wine terroir, volcanic rock. A pesquisa por gamaespectrometria tem permitido observar a distribuição de elementos radioativos, tais como K, U e Th reconhecendo as assinaturas radioativas de diferentes tipos de rocha. O objetivo deste estudo foi avaliar a possibilidade de distinguir entre as rochas ácidas e básicas da Formação Serra Geral, na região vitivinícola Serra Gaúcha, no estado do Rio Grande do Sul (Brasil) por meio de técnicas de gamaespectrometria Palavras-chave: m´étodos geofísicos, terroir vitivinícola, rocha vulcânica
Applicability of the Linear delta Expansion for the lambda phi^4 Field Theory at Finite Temperature in the Symmetric and Broken Phases
The thermodynamics of a scalar field with a quartic interaction is studied
within the linear delta expansion (LDE) method. Using the imaginary-time
formalism the free energy is evaluated up to second order in the LDE. The
method generates nonperturbative results that are then used to obtain
thermodynamic quantities like the pressure. The phase transition pattern of the
model is fully studied, from the broken to the symmetry restored phase. The
results are compared with those obtained with other nonperturbative methods and
also with ordinary perturbation theory. The results coming from the two main
optimization procedures used in conjunction with the LDE method, the Principle
of Minimal Sensitivity (PMS) and the Fastest Apparent Convergence (FAC) are
also compared with each other and studied in which cases they are applicable or
not. The optimization procedures are applied directly to the free energy.Comment: 13 pages, 10 eps figures, revtex, replaced with published versio
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